Page 1 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , UNIT – I, HUMAN ENDOCRINE SYSTEM, , The endocrine system is a network of glands and organs located throughout the body. It’s similar to, the nervous system in that it plays a vital role in controlling and regulating many of the body’s functions., However, while the nervous system uses nerve impulses and neurotransmitters for communication,, the endocrine system uses chemical messengers called hormones., , Hormones are special chemical messengers constantly present in circulation. The organ/tissue on, which the hormone acts is known as target organ. The study of hormones secreted by specialized, glands that are ductless is known as endocrine glands., Hormones are conventionally defined as organic substances, produced in small amounts by specific, tissues (of endocrine glands), secreted into the blood stream to control the metabolic and biological, activities in the target cells., , ROLE OF ENDOCRINE GLANDS:, 1., , Endocrine glands release hormones into the bloodstream. This lets the hormones travel to cells, in other parts of the body., , 2., , The endocrine hormones help control mood, growth and development, the way our organs, work, metabolism, and reproduction., , 3., , The endocrine system regulates quantity of hormone is released. This can depend on levels of, hormones already in the blood, or on levels of other substances in the blood, like calcium., , 1, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 2 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , CONCEPTS OF AUTOCRINE, PARACRINE, AND ENDOCRINE SECRETIONS:, AUTOCRINE:, Autocrines are chemical signals produced by the cell and influences the, activity of the cell itself., An example of an autocrine agent is the cytokine interleukin-1 in monocytes. When interleukin-1 is, produced in response to external stimuli, it can bind to cell-surface receptors on the same cell that, produced it., PARACRINE:, Paracrines are chemical signals produced by a cell and diffuse, in the surrounding area and act on the cells in the vicinity, without entering circulation., Somatostatin which regulates the secretion of insulin and glucagon in pancreas is a classic example, for paracrine., ENDOCRINE:, In endocrine signaling, the signaling molecules (hormones) are secreted by specialized endocrine, cells and carried through the circulation to act on target cells at distant body sites., A classic example is provided by the steroid hormone oestrogen, which is produced by the ovary and, stimulates development and maintenance of the female reproductive system and secondary sex, characteristics., , 2, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 3 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , TYPES OF HORMONES:, Hormones can be categorised into three distinct groups according to their chemical composition., The three types of hormones are steroid hormones, peptide hormones and amino acid derivatives., The different types of hormones will have different mechanisms of action due to their distinct chemical, properties, STEROID HORMONES:, 1. Steroid hormones are lipophilic (fat-loving) – meaning they can freely diffuse across the, plasma membrane of a cell., 2. They bind to receptors in either the cytoplasm or nucleus of the target cell, to form an active, receptor-hormone complex., 3. This activated complex will move into the nucleus and bind directly to DNA, acting as a, transcription factor for gene expression., 4. Examples of steroid hormones include those produced by the gonads (i.e., oestrogen,, progesterone and testosterone)., , 3, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 4 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , PEPTIDE HORMONES:, 1. Peptide hormones are hydrophilic and lipophobic (fat-hating) – meaning they cannot freely, cross the plasma membrane., 2. They bind to receptors on the surface of the cell, which are typically coupled to internally, anchored proteins (e.g. G proteins)., 3. The receptor complex activates a series of intracellular molecules called second messengers,, which initiate cell activity., 4. This process is called signal transduction, because the external signal (hormone) is transduced, via internal intermediaries., 5. Examples of second messengers include cyclic AMP (cAMP), Calcium ions (Ca2+), Nitric, oxide (NO) and protein kinases. The use of second messengers enables the amplification of, the initial signal (as more molecules are activated)., 6. Peptide hormones include insulin, glucagon, leptin, ADH and oxytocin., , 4, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 5 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , AMINE HORMONES:, 1. Amine hormones are derived from the amino acid tyrosine and include adrenaline, thyroxin, and triiodothyronine., 2. Amine hormones do not all share identical properties and have properties common to both, peptide and steroid hormones., , SUMMARY OF DIFFERENT CLASSES OF HORMONES:, , ROLE OF HORMONES IN HOMEOSTASIS:, Homeostasis is the regulation of the internal conditions within cells and whole organisms such as, temperature, water, and sugar levels. Hormones are responsible for key homeostatic processes, including Control of blood glucose levels and Control of blood pressure., , 5, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 6 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , EXAMPLE 1:, CONTROL OF BLOOD GLUCOSE LEVELS:, This refers to the maintenance of normal glucose levels in the blood and is an important process which, includes various muscles, kidneys, and the liver, which all play an important role in regulating the levels, of glucose in the blood., However, the organ that plays the most important role in this process is the liver. This organ is the, most important in keeping glucose levels at a normal range by storing glycogen and preventing, decrease of blood glucose levels. Blood Glucose is important because it provides the energy needed to, keep our brain/nervous system going. In order for these two systems to function properly and receive, the energy needed, glucose levels should remain within the range of 80 to 120 mg/dL., , 6, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 7 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 1. Soon after the meal when the blood glucose level raises the rate of insulin hormone is secreted, by the β-cells of pancreas., 2. The insulin hormone converts the excess of glucose into glycogen & stored in liver and, muscle. This physiological and biochemical process is called, Glycogenesis., 3. After few hours when glucose concentration decreases the insulin secretions also decrease., 4. When the blood glucose falls below the normal the α-cells of the pancreas secrete glucagon, hormone., 5. In liver glucagon hormone induces the breakdown of glycogen (polysaccharide) into glucose, (monosaccharide) and release the glucose back into the blood. This physiological and, biochemical process is known as Glycogenolysis., 6. When the amount of stored up glycogen in the muscle and liver gets reduced, then the amino, acids and fatty acids enter the process of Gluconeogenesis in the liver which results in the, production of glucose, so liver has an important role in the finely regulated homeostatic, mechanism., 7. Gluconeogenesis is the process of synthesis of glucose from non-carbohydrate compounds, such as lactate, pyruvate, glucogenic Aminoacids, propionate and glycerol., , EXAMPLE 2:, CONTROL OF BLOOD PRESSURE:, There are several physiological mechanisms that regulate blood pressure in the long-term, the first of, which is the renin-angiotensin-aldosterone system (RAAS)., 1. Renin is a peptide hormone released by the granular cells of the juxtaglomerular apparatus, in the kidney., 2. Renin is released in response to: Sympathetic stimulation, Reduced sodium-chloride delivery, to the distal convoluted tubule and Decreased blood flow to the kidney., , 7, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 8 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 3. Renin facilitates the conversion of angiotensinogen to angiotensin I which is then converted, to angiotensin II using angiotensin-converting enzyme (ACE)., 4. Angiotensin II is a potent vasoconstrictor. It acts directly on the kidney to increase sodium, reabsorption in the proximal convoluted tubule. Sodium is reabsorbed via the sodium-hydrogen, exchanger., 5. Angiotensin II also promotes release of aldosterone., 6. More sodium collects in the kidney tissue and water then follows by osmosis. This results in, decreased water excretion and therefore increased blood volume and thus blood pressure., 7. The second mechanism by which blood pressure is regulated is release of Anti Diuretic, Hormone (ADH) from the hypothalamus in response to thirst or an increased plasma osmolarity., 8. ADH acts to increase the permeability of the collecting duct to water by inserting aquaporin, channels (AQP2) into the apical membrane., 9. It also stimulates sodium reabsorption from the thick ascending limb of the loop of Henle., This increases water reabsorption thus increasing plasma volume and decreasing, osmolarity., 8, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 9 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , Other factors that can affect long-term regulation of blood pressure are natriuretic peptides., These include:, 10. Atrial natriuretic peptide (ANP) is synthesised and stored in cardiac myocytes. It is released, when the atria are stretched, indicating of high blood pressure., 11. ANP acts to promote sodium excretion. It dilates the afferent arteriole of the glomerulus,, increasing blood flow (GFR). Moreover, ANP inhibits sodium reabsorption along the nephron., Conversely, ANP secretion is low when blood pressure is low., 12. Prostaglandins act as local vasodilators to increase GFR and reduce sodium reabsorption., They also act to prevent excessive vasoconstriction triggered by the sympathetic nervous and, renin-angiotensin-aldosterone systems., MORPHOLOGY, HORMONES AND THEIR ACTIONS OF PITUITARY GLAND:, 1. The pituitary gland is the smallest endocrine gland. The pituitary gland is located just below, the hypothalamus. The pituitary gland is situated in a depression the sella turcica of sphenoid, bone of the skull., 2. It is about 1.3 cm in diameter and weighs about half a gram. The gland is attached to the, brain by a stalk the infundibulum which is continuous with the hypothalamus above., 3. The pituitary gland is formed of two main lobes of different origin with one intermediate lobe., , 9, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 10 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 4. These lobes are the much larger anterior lobe or adenohypophysis or pars distalis and the, smaller posterior lobe or neurohypophysis or pars nervosa., 5. A third lobe, called the intermediate lobe or pars inter-media is a part of adenohypophysis., 6. Adenohypophysis comprises about 75% part of the pituitary gland. The hypophysial portal, veins carry blood containing neurohormones (releasing factors) from the hypothalamus to the, adenohypophysis., 7. Neurohypophysis comprises about 25% part of the pituitary gland. The axons of, neurosecretory cells (secretory neurons) extend into the neurohypophysis where these axons, terminate as axon terminals., 8. These terminals are embedded in a neuroglial tissue formed of large and branched cells called, pituicytes., , HORMONES OF THE ANTERIOR LOBE AND THEIR ACTION:, The anterior lobe of the pituitary gland secretes the following hormones, most of them are trophic, hormones., 1. Growth hormone (GH) or Somatotrophin (STH): This hormone stimulates growth. Growth, hormone promotes protein anabolism, the absorption of calcium from the bowel and the, conversion of glycogen to glucose., 2. Thyroid stimulating hormone (TSH) or Thyrotropin: This hormone controls the growth and, activity of the thyroid gland. It influences the uptake of iodine, the synthesis of the hormones,, thyroxine and tri-iodothyronine by the thyroid gland and the release of stored hormones into, the blood stream., 3. Adrenocorticotropic hormone (ACTH): This hormone stimulates the cortex of the adrenal, gland to produce its hormones., 10, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 11 :
ZOOLOGY – DSE 1A, , 4., , ENDOCRINOLOGY AND REPRODUCTON, , Prolactin hormone (PRL): Prolactin is also called the “hormone of maternity” because its, main physiological effect is to activate growth of breasts during pregnancy and secretion of, mammary glands after child birth. It is also referred by name luteotrophic hormone (LTH), because it also stimulates the corpus luteum of the ovary to secrete progesterone hormone., , 5. Gonadotropic hormones: These are as follows:, Follicle-stimulating hormone (FSH): It stimulates growth of ovarian follicles and their, secretion of oestrogens in the female, and spermatogenesis (formation of sperms) in the male., Luteinizing hormone (LH): In female it stimulates the corpus luteum of the ovary to secrete, progesterone. In male it activates the Leydig’s (interstitial) cells of the test is to secrete, androgens hence it may be called interstitial cell stimulating hormone (ICSH) in male., , HORMONES OF THE INTERMEDIATE LOBE AND THEIR ACTION:, The intermediate lobe of the pituitary gland secretes melanotrophin or melanocyte stimulating, hormone (MSH). This hormone causes dispersal of pigment granules in the pigment cells, thereby, darkening the colour in certain animals like fishes and amphibians. It is believed that it is associated, with the growth and development of melanocytes in man which give colour to the skin., , HORMONES OF THE POSTERIOR LOBE AND THEIR ACTION:, The secretion of the posterior lobe is known as pituitrin and it contains two hormones: Oxytocin and, Antidiuretic hormone (ADH) or vasopressin., , Once again it is reminded that the posterior lobe of the pituitary gland does not secrete any hormone., Its hormones are secreted in the hypothalamus., , 11, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 12 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 1. Oxytocin (ОТ): Oxytocin promotes contraction of the uterine muscle and contraction of the, myoepithelial cells of the lactating breast, squeezing milk into the large ducts behind the, nipple. In late pregnancy the uterus becomes very sensitive to oxytocin., The amount secreted is increased just before and during labour and by sucking of the baby., Because of its role, oxytocin is called “birth hormone” and “milk ejecting hormone”., 2. Antidiuretic hormone (ADH) or Vasopressin: This hormone has two main functions:, Antidiuretic effect: It increases the reabsorption of water in the distal convoluted tubule and, collecting ducts of the nephrons of the kidneys. As a result, the reabsorption of water from the, glomerular filtrate is increased,, Pressor effect: Involuntary muscles in the walls of the intestine, gall bladder, urinary bladder, and blood vessels are stimulated to contract by ADH. Contraction of the walls of the blood, vessels raises the blood pressure and this may be its most important pressor effect., , The pituitary gland is also called “Master Endocrine Gland” of body or the “Chief Executive of, Endocrine System” or “The Leader of Endocrine Orchestra” as it secretes the number of hormones, (e.g., TSH, ACTH etc.) which regulate the working of other endocrine glands., But it is not proper to call it as master endocrine gland because it is itself under the control of the, releasing hormones secreted by the hypothalamus of the brain. Thus the hypothalamus is, in fact,, the supreme commander of endocrine regulation., , 12, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 13 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , MORPHOLOGY, HORMONES AND THEIR ACTIONS OF THYROID GLAND:, , 1. The thyroid gland is the largest endocrine gland located anterior to the thyroid cartilage of, the larynx in the neck., 2. It is bilobed organ and well supplied with blood vessels., 3. The two lobes are connected by a narrow structure called the isthmus. The microscopic, structure of the thyroid gland shows thyroid follicles composed of cubical epithelium and, filled with a homogenous material called colloid., 4. Small amount of loose connective tissue forms stroma of the gland. Besides containing blood, capillaries, the stroma contains small clusters of specialized Para follicular cells or ‘C’ cells., , 13, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 14 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , HORMONES OF THE THYROID GLAND AND THEIR ACTION:, The thyroid gland secretes three hormones. Thyroxine (tetra-iodothyronine or T4), and triiodothyronine or T3 are secreted by the thyroid follicular cells. Thyrocalcitonin is secreted by the Сcells of the thyroid gland. This gland is stimulated to secrete its hormones by thyroid stimulating, hormone (also called thyrotropin) secreted by the anterior lobe of pituitary gland., , 1. Thyroxine (T4) and Triiodothyronine (T3):, T4 and T3 contain four and three atoms of iodine respectively, therefore, they are named so., T3 is secreted in smaller amounts but it is more active and several times more potent than, T4. T4 is converted to T3 by removal of one iodine in the liver, kidneys and some other tissues., Since both T4 and T3 have similar effects on the target cells, they are generally considered, together under the name, thyroid hormone (TH)., The thyroid gland is the only gland that stores its hormones in large quantity. T4 and T3 are, synthesised by attaching iodine to tyrosine amino acid., The functions of thyroxine (T4) and tri-iodothyronine (T3) are as follows:, 1. They regulate the metabolic rate of the body and thus maintain basal metabolic rate, (BMR)., 2. They stimulate protein synthesis and, therefore, promote growth of the body tissues., 3. They regulate the development of mental faculties., 4. As they increase heat production, thus they maintain body temperature., 5. They increase action of neurotransmitters like adrenaline and noradrenaline., , 14, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 15 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 2. Thyrocalcitonin (TCT):, It is secreted when calcium level is high in the blood. It then lowers the calcium level by, suppressing release of calcium ions from the bones. Thus calcitonin has an action opposite to, that of the parathyroid hormone on calcium metabolism. Calcitonin is a peptide which contains, 32 amino acids., , MORPHOLOGY, HORMONES AND THEIR ACTIONS OF PARATHYROID GLAND:, , 1. The parathyroid glands consist of four separate glands located on the posterior surface of the, lobes of the thyroid gland., 2. The cells of parathyroid glands are arranged in a compact mass and are of two types: small, chief cells (or principal cells) and large oxyphil cells (or eosinophil cells)., 3. The cells are enclosed by a delicate connective tissue capsule. The chief cells are much more, numerous than the oxyphil cells. The latter are absent in the young and appear a little before the, age of puberty., , 15, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 16 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , HORMONES OF THE PARATHYROID GLAND AND THEIR ACTION:, The chief cells of the parathyroid secrete a hormone called parathyroid hormone (PTH) or, parathormone or also called Collip’s hormone after the name of its discoverer., 1. This hormone regulates the calcium and phosphate balance between the blood and other, tissues., 2. PTH inhibits collagen synthesis by osteoblasts and bone resorption by osteoclasts., 3. It mobilises the release of calcium into the blood from the bones., 4. PTH increases calcium absorption from the intestines., 5. It increases calcium resorption from the nephrons (and inhibits phosphate resorption) of the, kidneys. Thus parathormone regulates the metabolism of calcium and phosphate., , MORPHOLOGY, HORMONES AND THEIR ACTIONS OF ADRENAL GLAND:, , 16, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 17 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 1. Adrenal Glands are paired structures located on the top of the kidneys. Each adrenal gland, has two parts external adrenal cortex and internal adrenal medulla., 2. The adrenal cortex occupies outer peripheral portion and is yellowish in colour., Histologically it is subdivided into three zones:, a. Zona glomerulosa (zona- belt, glomerul- little ball):, This is the outer zone that lies just below the capsule. It constitutes about 15% of the, gland. Its cells are closely packed and arranged in spherical clusters and arched columns, which secrete hormones called mineralocorticoids because they affect mineral, homeostasis., b. Zona fasciculata (fascicul-little bundle):, This is the middle zone which is widest of the three zones. It constitutes about 50% of the, gland. It consists of the cells arranged in long, straight columns. The cells of this zone, secrete mainly glucocorticoids, which are named because they affect glucose homeostasis., c. Zona reticularis (reticul- network):, This is the inner zone that constitutes about 7% of the gland. The cells are arranged in, branching cords which secrete gonado-corticoids (e.g., androgens that have masculinizing, effects)., 3. Adrenal medulla: active principles of adrenal medulla are ‘Catecholamines’ – Adrenaline, (Epinephrine) and Noradrenaline (Nor-epinephrine). In human, adrenal medulla contains, 80% of epinephrine and 20% nor-epinephrine., Functions of Adrenaline (Epinephrine):, a) Epinephrine gives a rapid physiologic response to emergencies such as cold, fatigue,, shock etc. In this sense, it mobilizes the terms “fight or flight” mechanism., , 17, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 18 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , b) They increase blood pressure., c) Epinephrine increases cAMP by activating adenylate cyclase. cAMP stimulates, phosphorylase which causes the breakdown of glycogen in the liver resulting in, increased blood sugar. Norepinephrine is one-fifth potent in this respect., d) Epinephrine causes increased breakdown of muscle glycogen to lactic acid, thereby, increasing blood lactate., e) Epinephrine acts on adipose tissue and releases free fatty acids into the circulation., f) Epinephrine also increases BMR., g) Epinephrine is an effective stimulant of heart action. It increases the irritability and the, rate and strength of contraction of cardiac muscle and increases cardiac output. It causes, vasodilatation of the arterioles of the skin and mucous membranes. Norepinephrine has, less effect on cardiac output., h) Epinephrine causes relaxation of the smooth muscles of the stomach, intestine,, bronchioles and urinary bladder., , HORMONES OF THE ADRENAL GLAND AND THEIR ACTION:, All hormones of adrenal cortex are synthesized from cholesterol. Corticosteroids (corticoids—, hormones of adrenal cortex) are grouped into three categories: mineralocorticoids, glucocorticoids, and gonado corticoids., 1. Mineralocorticoids: These hormones are secreted by the cells of zona glomerulosa of adrenal, cortex. As the name indicates, they are responsible for the regulation of mineral metabolism., Aldosterone (salt-retaining hormone) is the principal mineralocorticoid (90 to 95%) in, humans. Its main function is to regulate the sodium content of the body. It is secreted when the, sodium level is low., , 18, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 19 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , It acts on the kidneys to cause more sodium to be returned to the blood and more potassium, to be excreted. As the sodium concentration in the blood increases, water follows it by osmosis,, so the blood volume also increases. Thus the effect of aldosterone is to increase both sodium and, water in the blood., 2. Glucocorticoids: As their name suggests, they affect carbohydrate metabolism, however, they, also affect the metabolism of proteins and fats., Glucocorticoids include three main hormones: cortisol (= hydrocortisone), corticosterone and, cortisone., Of the three, cortisol is the most abundant (about 95%). It stimulates the liver to synthesize, carbohydrates from non-carbohydrates such as amino acids and glycerol. Thus increases, level of glucose in the blood., Cortisol also stimulates the degradation of proteins within cells and amino acids in the blood,, therefore, increases level of amino acids in the blood., A third effect of cortisol is to stimulate the break-down of fats in adipose tissue and release, fatty acids into the blood. Thus cortisol has anti insulin effect., It also helps in reducing pain and is anti-inflammatory. It retards phagocytic activities of, WBCs and thus suppresses ‘inflammation reaction’. This hormone also reduces the number of, mast cells, reducing secretion of histamine., Cortisol is also “immunosuppressive”. It suppresses synthesis of antibodies by inhibiting the, production of lymphocytes in the lymphoid tissues., It also elevates blood pressure. Cortisol has the capacity to cope with stress. When we are, under stress our body secretes cortisol that is why this hormone is called “stress hormone”., , 19, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 20 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 3. Gonad corticoids (Sex-corticoids): They are also called sex hormones of adrenal glands. Large, quantities of male than female sex-corticoids (sex hormones) are produced. These male sex, hormones are called androgens which are important in the development of a male foetus., Although the genetic sex is determined by the chromosomes in a fertilized egg, a male foetus, develops normal male characteristics only if the foetal gonads and adrenal glands produce, sufficient quantities of androgens., Therefore, androgens stimulate the development of male secondary sexual characters like, distribution of body hair. Female sex hormones secreted by the adrenal cortex are oestrogens, which maintain the development of female secondary sexual characters., , MORPHOLOGY, HORMONES AND THEIR ACTIONS OF PANCREAS:, , 20, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 21 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 1. Pancreas is a dual organ. It has endocrine portion and exocrine portion., 2. Pancreas is elongated 12-15 cm long organ consisting of head, body and tail., 3. It is located posterior to stomach with its head in the curve of duodenum. The body and tail, extends laterally. The tail touches the spleen., 4. As exocrine gland, pancreas secretes digestive enzymes into pancreatic duct and endocrine, gland, it secretes hormones into blood., 5. Only about 1% of total weight of gland acts as endocrine gland. This portion of pancreas is, known as Islet of Langerhans. Adult pancreas contains 200,000-20,00,000 Islet of Langerhans., 6. Endocrine portion of pancreas is called Islet of Langerhans, which is a group of cells., Alpha cell:, These cells produce glucagon. Glucagon plays an important role in blood glucose regulation;, low blood glucose levels stimulate its release., Beta cell:, These cells produce Insulin. Elevated blood glucose levels stimulate the release of insulin., Delta cell:, These cells produce peptide hormone Somatostatin. Pancreatic somatostatin inhibits the release, of both glucagon and insulin. (* somatostatin is also released by the hypothalamus (as GHIH),, and the stomach and intestines), F cell (PP cell):, These cells produce pancreatic polypeptide hormone., , 21, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 22 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , FUNCTIONS OF INSULIN:, Insulin is secreted from β-cells of islets. It shows following functions;, On carbohydrate metabolism:, 1. It stimulates glycogenesis in muscle cells and liver by increasing activities of glycogen, synthetase, hexokinase II and a microsomal glucokinase., 2. It enhances combustion of sugar by inducing glycolysis with the help of pyruvate kinase,, glucokinase and phosphofructokinase., 3. It regulates hepatic gluconeogenesis by inducing pyruvate carboxylase, G-6-phosphatase etc., , On protein metabolism:, 1. It stimulates the synthesis of tissue protein by taking amino acids from blood., 2. It depresses protein catabolism and reduces the process of gluconeogenesis from protein., , On fat metabolism:, 1. It helps in the accumulation of adipose fat i.e. lipogenesis. It produces pyruvic acid from, glucose oxidation, the part of the pyruvic acid after decarboxylation is converted to acetic acid, which will give rise to neutral fats., 2. It increases the activity of lipoprotein lipase in adipose tissues., 3. It increases ketone bodies from fatty acids in liver. The presence of ketone bodies can cause, severe acidosis and coma in patients., 4. It reduces the free fatty acids level in blood by depressing the activity adipose tissue lipase., , 22, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 23 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , FUNCTIONS OF GLUCAGON:, It is secreted from a-cells of pancreatic islets. It performs following functions;, On carbohydrate metabolism:, 1. It increases liver glycogenesis’ and increased blood glucose concentration. It has no effect on, glycogen phosphorylase of muscles., 2. It depresses glycogenesis in the liver by reducing glycogen synthetase activity., 3. It increases the gluconeogenesis in the liver from proteins by inducing pyruvate carboxylase., On protein metabolism:, 1. It reduces protein synthesis by depressing the incorporation of amino acids into peptide chains., 2. It stimulates protein catabolism and thus increases nitrogenous waste metabolites., On fat metabolism:, 1. It increases free fatty acids and glycerol in blood by lipolysis., 2. It increases adenyl cyclase activity in adipose tissue that results in increased lipolysis., 3. It has ketogenic effects. It increases fatty acid oxidation and ketosis to supply more fatty acids, to the liver., FUNCTIONS OF SOMATOSTATIN:, 1. It may control the peristaltic activity of GI tract., 2. It may regulate insulin and glucagon secretion by paracrine action., 3. It helps in transport of nutrients from GI tract to the circulation., 4. It decreases HCI secretion of stomach in empty state., 23, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 24 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , MORPHOLOGY, HORMONES AND THEIR ACTIONS OF PINEALGLAND:, , 1. The pineal body is also called the epiphysis cerebri, is relatively a small organ, shaped like a, pine cone, hence its name., 2. It is located in the geometric centre of the brain directly behind the eyes, below the corpus, collosum and posterior to the third ventricle., 3. The pineal body originates as a sac-like evagination from the dorsal part of the, diencephalon., 4. It is reddish-grey in colour and in approximately 10 mm long, is surrounded by a fine capsule, and is composed of epithelial cells arranged to form lobules that are surrounded by fine, connective tissue., 5. Histologically, the pineal is composed of ‘pinealocytes’ and glial cells., 6. Pinealocytes are like neurons, stellate (star shaped) and arranged in cluster. These cells are, sensitive to light and receive signals via the retina of the eyes., 7. Glial cells are elongated and run between nests of pinealocytes., , 24, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 25 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , HORMONES AND THEIR ACTIONS OF PINEALGLAND:, The pineal gland synthesizes and secretes hormone known as melatonin., , 1. Effects on reproductive function:, Melatonin inhibits the secretion of the gonadotropic hormones, luteinizing hormone (LH), and follicle stimulating hormone (FSH) from the anterior pituitary. Thus, prevent the onset of, puberty before the appropriate age., 2. Effects on sleep and activity:, Blood levels of the pineal hormone melatonin are high at night and low during the day., Melatonin has both a soporific effect and an ability to entrain the sleep-wake rhythm., 3. Other effects of melatonin:, It also has a major role in regulating the body temperature rhythm., It may involve in distribution of melanin pigment in amphibians and birds., Studies done on birds, suggest that the pineal gland is centre for navigation., , NEURO-HORMONES – HYPOTHALAMIC RELEASING FACTORS AND THEIR ACTIONS:, Hormone secretion from the pituitary is controlled and regulated by the hormones from the, hypothalamus., The hypothalamus sends axon to the capillary bed of the anterior pituitary and these nerve ends liberate, chemical substances called neurohormones or hypothalamic releasing factors., Hypothalamus secretes both releasing and inhibitory hormones controlling the secretions of some, anterior pituitary hormones. Hence these hormones are also called releasing factors., , 25, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 26 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , At present nine discrete regulatory factors have been described that may affect the synthesis as well, as secretion of specific pituitary hormones. They are listed as under;, 1. Thyrotropin Releasing Hormone (TRH):, It targets the anterior lobe of the pituitary and stimulates the gland to secrete thyroid stimulating, hormones (TSH)., 2. Adrenocorticotropic Releasing Hormone (ARH):, This hormone shows its effect on adrenal gland and responsible for release of adrenal hormones., 3. Growth Hormone Releasing Hormone (GHRH):, This hormone targets the anterior pituitary cells and induces them to secrete growth hormone., 4. Growth Hormone Inhibiting Hormone (GHIH) or Somatostatin:, This hormone is antagonist to the GH, which suppress the production of GH., 5. Prolactin Releasing Hormone (PRH):, PRH enhances the secretion of Prolactin Hormone from the anterior pituitary., 6. Prolactin Inhibiting Hormone (PIH):, This hormone inhibits the secretion of Prolactin Hormone., 7. Gonadotropin Releasing Hormone (GnRH):, GnRH act over the cells of the anterior pituitary and responsible for the release of, Gonadotrophins like Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)., 8. Melanocyte Stimulating Hormone Releasing Hormone (MSHRH):, MSH-Releasing Hormone stimulates the intermediate lobe of the pituitary and induces the, secretion of Melanocyte Stimulating Hormone (MSH)., 9. Melanocyte Stimulating Hormone Inhibiting Hormone (MSHIH):, MSH-Inhibiting Hormone inhibits the secretion of MSH., ******, , 26, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 27 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , UNIT – II, HORMONE RECEPTORS, , A hormone receptor is a protein molecule that binds to a specific hormone. Most hormones circulate, in blood, coming into contact with essentially all cells. However, a given hormone usually affects only, a limited number of cells, which are called target cells. A target cell responds to a hormone because it, bears receptors for the hormone., , In other words, a particular cell is a target cell for a hormone if it contains functional receptors for that, hormone, and cells which do not have such a receptor cannot be influenced directly by that hormone., , Hormone receptors are found either exposed on the surface of the cell or within the cell, depending, on the type of hormone. In very basic terms, binding of hormone to receptor triggers a cascade of, reactions within the cell that affects function., , 27, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 28 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , TYPES OF HORMONE RECEPTORS:, A hormone receptor is a receptor molecule that binds to a specific hormone., INTRACELLULAR (CYTOPLASMIC / NUCLEAR RECEPTORS):, 1. Intracellular and nuclear receptors are a direct way for the cell to respond to internal changes, and signals., 2. Intracellular receptors are activated by hydrophobic ligands that pass through the cellular, membrane., 3. Intrinsic transcriptional involves the three following domains: transcription-activating, DNAbinding, and ligand-binding., 4. These domains and ligands are hydrophobic and are able to travel through the membrane., 5. The movement of macromolecules and ligand molecules into the cell enables a complex transport, system of intracellular signal transfers through different cellular environments until response, is enabled., 6. Nuclear receptors are a special class of intracellular receptor that specifically aid the needs, of the cell to express certain genes., 7. Nuclear receptors often bind directly to DNA by targeting specific DNA sequences in order, to express or repress transcription of nearby genes., , TRANS-MEMBRANE RECEPTORS:, 1. The extracellular environment is able to induce changes within the cell. Hormones, or other, extracellular signals, are able to induce changes within the cell by binding to membrane-bound, receptors., , 28, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 29 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 2. This interaction allows the hormone receptor to produce second messengers within the cell to, aid response., 3. Second messengers may also be sent to interact with intracellular receptors in order to enter, the complex signal transport system that eventually changes cellular function., 4. G-protein-coupled membrane receptors (GPCR) are a major class of transmembrane, receptors. The features of G proteins include GDP/GTP binding, GTP hydrolysis and guanosine, nucleotide exchange., , OUTLINES OF MECHANISM OF HORMONE ACTION:, It is generally considered that a hormone, in order to act, must first bind to specific receptors on their, effector cell (target cell), the union of which then triggers a chain of events that dramatically change the, pre-existing patterns for synthesis of enzymes or function., There are two important general mechanisms by which hormones act on the cells;, 1. Activation of the cyclic AMP (cAMP) system of the cells, which in turn elicits cellular function,, or, 2. Regulation of the genes in the nucleus of the cell which then synthesize protein or enzyme that, in turn initiates the cellular response., cAMP PATHWAY:, Earl Sutherland, Edwin Krebs and Edmond Fischer (1950), elucidate the connection between the, binding of the hormone to plasma membrane and the change in the activities of phosphorylase and, glycogen synthase., A wide variety of hormones (acting as first messengers) use cAMP as secondary messenger, a, substance that is released into the interior of the cell as a result of binding of a first messenger (hormone)., , 29, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 30 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , Cyclic Adenosine Monophosphate (cyclic AMP, or simply cAMP) is produced from ATP by an, enzyme, adenylate cyclase that is attached to the inside of the cell membrane., The cascade of reactions involved in the production of glucose by liver cells under the influence of, glucagon or epinephrine mediated by cAMP is illustrated as below;, , 1. The hormone glucagon or epinephrine (first messenger) binds to the outer surface of a liver, cell that cause a change in the conformation of the receptor., 2. Then it is transmitted across a plasma membrane and activates adenylate cyclase at the, membrane’s inner surface., 3. On activation, adenylate cyclase catalyses the conversion of ATP into cyclic AMP (secondary, messenger)., 4. The cAMP rapidly diffuses into the cytoplasm where it evokes a response by triggering a chain, of reactions., 5. Each cAMP then activates the enzyme Protein Kinase A (PKA) which is able to, phosphorylate another enzyme Phosphorylase Kinase., 6. The phosphorylase kinase in turn catalyses the breakdown of glycogen into glucose-1phosphate and finally to glucose., 7. The glucose diffuses into blood and reaches the tissues of the body., 30, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 31 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , GENOMIC ACTION: (CYCLIC AMP – MEDIATED SIGNAL TRANSDUCTION FOR, ACTIVATION OF GENES), It has been described how cAMP is produced in cytoplasm and in turn activates the PKA (Protein Kinase, A). while most of the activated PKA molecules remain in the cytoplasm, some of them play a significant, role in activation of genes., , 1. PKA is a part of an important pathway of gene control., 2. A fraction of cytoplasmic PKA translocate into nucleus where it phosphorylates nuclear, protein called CREB (cAMP Responsive Element Binding protein)., 3. The phosphorylates CREB becomes an active transcriptional factor that bind to the DNA, having a particular sequence of nucleotides that are known as the cAMP-Regulated Enhancer, (CRE)., 4. The binding of phosphorylated CREB and CRE on DNA initiates the transcription and, synthesis of mRNA that in turn translated to form anabolic enzymes., 5. Thus, when the liver cell shows response to glucagon or epinephrine, it activates not only the, catabolic enzymes that are required for breakdown of glycogen but also the genes containing, CREs for the synthesis of anabolic enzymes required to form glucose from non-carbohydrate, precursors (the process is called gluconeogenesis)., 31, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 32 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , UNIT – III, HUMAN ENDOCRINE DISORDERS, , The endocrine system consists of a group of glands and organs that regulate and control various, body functions by producing and secreting hormones., Hormones are chemical substances that affect the activity of another part of the body. In essence,, hormones serve as messengers, controlling and coordinating activities throughout the body., Endocrine disorders are typically grouped into two categories:, , 1., , Endocrine disease that results when a gland produces too much or too little of an endocrine, hormone, called a hormone imbalance., , 2., , Endocrine disease due to the development of lesions (such as nodules or tumors) in the endocrine, system, which may or may not affect hormone levels., , Increased or decreased levels of endocrine hormone may be caused by:, , 1., , A problem with the endocrine feedback system., , 2., , Disease or infection, , 3., , Failure of a gland to stimulate another gland to release hormones (for example, a problem with, the hypothalamus can disrupt hormone production in the pituitary gland), , 4., , A, , genetic, , disorder,, , such, , as, , multiple, , endocrine, , neoplasia, , (MEN), , or, , congenital hypothyroidism., 5., , Injury to an endocrine gland., , 6., , Tumour of an endocrine gland., , 32, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 33 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , GIGANTISM:, , Gigantism is a rare condition that causes abnormal growth in children. This change is most notable in, terms of height, but girth is affected as well., , It occurs when your child’s pituitary gland makes too much growth hormone, which is also known as, somatotropin., , CAUSES OF GIGANTISM:, 1. A pituitary gland tumour is almost always the cause of gigantism. When a tumour grows on the, pituitary gland, the gland makes far more growth hormone than the body needs., 2. McCune-Albright syndrome causes abnormal growth in bone tissue, patches of light-brown, skin, and gland abnormalities., 3. Multiple Endocrine Neoplasia type 1 (MEN1) is an inherited disorder that causes tumors in, the pituitary gland, pancreas, or parathyroid glands., 4. Neurofibromatosis is an inherited disorder that causes tumors in the nervous system., SYMPTOMES OF GIGANTISM:, 1., , Very large hands and feet., , 2., , Thick toes and fingers., , 3., , A prominent jaw and forehead., , 4., , Coarse facial features., , 5., , Children with gigantism may also have flat noses and large heads, lips, or tongues., , 6., , Many people experience headaches, vision problems, or nausea from tumors in this, area., , 33, , 7., , Excessive sweating, , 8., , Severe or recurrent headaches, LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 34 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 9., , Weakness, , 10., , Insomnia and other sleep disorders, , 11., , Delayed puberty in both boys and girls, , 12., , Irregular menstrual periods in girls, , 13., , Deafness, , DWARFISM:, Dwarfism is a medical or genetic condition that causes someone to be considerably shorter than an, average-sized man or woman., The average height of an adult with dwarfism is 4 feet, but dwarfism could apply to an adult who is, 4’10” or shorter., TYPES OF DWARFISM:, Though there are many different causes of dwarfism, there are two main types of the condition:, PROPORTIONATE DWARFISM:, When the head, trunk, and limbs are all proportionate to each other, but much smaller than those of, an average-sized person, the condition is known as proportionate dwarfism., This type of dwarfism is often the result of a hormone deficiency. It can often be treated with hormone, injections while a child is still growing. As a result, someone born with proportionate dwarfism may be, able to reach an average height or get close to it., DISPROPORTIONATE DWARFISM:, This is the most common kind of dwarfism. As the name suggests, it’s characterized by having body, parts that are disproportionate to each other., , 34, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 35 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , For example, a genetic condition called achondroplasia results in arms and legs that are significantly, shorter than those of a person of average size, but the trunk is like that of someone unaffected by, dwarfism. In some cases, the head of a person with disproportionate dwarfism may be slightly larger, than that of a person without dwarfism., CAUASES OF DWARFISM:, Researchers believe there are more than 300 conditions that cause dwarfism. Most causes are genetic., The most common causes include:, 1. Achondroplasia: Though achondroplasia is a genetic condition, four out of five people who, have it also have two parents who are average sized. If you have achondroplasia, you have one, mutated gene associated with the condition and one unaffected version of that gene. This is the, most common cause of dwarfism., 2. Turner syndrome:, , This condition affects only females. Instead of inheriting two fully, , functioning X chromosomes from your parents, you inherit one X chromosome and are missing, a second, or at least part of a second, X chromosome. Males, by comparison, have an X, chromosome and a Y chromosome., 3. Growth hormone deficiency: The reasons for growth hormone deficiency aren’t always clear., Sometimes it’s tied to a genetic mutation. In many cases, the reasons for growth hormone, deficiency are never diagnosed., 4. Hypothyroidism: An underactive thyroid, especially if it develops at a young age, can lead to, many health problems, including limited growth. Other complications include low energy,, cognitive problems, and puffy facial features., 5. Intrauterine growth retardation: This condition develops while the baby is still in the mother’s, womb. The pregnancy may go to full term, but the baby is usually much smaller than average., The result is typically proportional dwarfism., 6. Genetics and other risk factors: Dwarfism is usually the result of a genetic mutation. But, having a gene or genes responsible for dwarfism can occur in a couple of ways., 35, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 36 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , SYMPTOMES OF DWARFISM:, The most common cause of dwarfism is a disorder called achondroplasia, which causes, disproportionately short stature. This disorder usually results in the following:, , 1., , An average-size trunk, , 2., , Short arms and legs, with particularly short upper arms and upper legs, , 3., , Short fingers, often with a wide separation between the middle and ring fingers, , 4., , Limited mobility at the elbows, , 5., , A disproportionately large head, with a prominent forehead and a flattened bridge of the nose, , 6., , Progressive development of bowed legs, , 7., , Progressive development of swayed lower back, , 8., , An adult height around 4 feet (122 cm), , Another cause of disproportionate dwarfism is a rare disorder called spondyloepiphyseal dysplasia, congenita (SEDC). Signs may include:, , 1., , A very short trunk, , 2., , A short neck, , 3., , Shortened arms and legs, , 4., , Average-size hands and feet, , 5., , Broad, rounded chest, , 6., , Slightly flattened cheekbones, , 36, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 37 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 7., , Opening in the roof of the mouth (cleft palate), , 8., , Hip deformities that result in thighbones turning inward, , 9., , A foot that's twisted or out of shape, , 10., , Instability of the neck bones, , 11., , Progressive hunching curvature of the upper spine, , 12., , Progressive development of swayed lower back, , 13., , Vision and hearing problems, , 14., , Arthritis and problems with joint movement, , 15., , Adult height ranging from 3 feet (91 cm) to just over 4 feet (122 cm), , ACROMEGALY:, Acromegaly is a rare hormonal condition that results from an excess amount of growth hormone, (GH) in the body. The extra amount of GH causes excess growth in the bones and soft tissues of the, body., Children with the condition can grow to abnormal heights. They may also have an exaggerated bone, structure. Acromegaly mostly affects the arms, legs, and face., SYMPTOMES OF ACROMEGALY:, 1. Enlarged bones in the face, feet, and hands, 2. Excessive hair growth in women, 3. An enlarged jaw or tongue, 4. A prominent brow, 5. Excessive growth spurts, which are more common in people who’ve had abnormal, growth before adolescence, 6. Weight gain, 37, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 38 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 7. Swollen and painful joints that limit movement, 8. Spaces between the teeth, 9. Splayed fingers and toes, 10. A hoarse, deep voice, 11. Fatigue, 12. Headaches, 13. An inability to sleep, 14. Muscle weakness, 15. Profuse sweating, 16. Body odour, 17. Enlarged sebaceous glands, which are glands that produce oils in the skin, 18. Thickened skin, 19. Skin tags, which are noncancerous growths, CAUSES OF ACROMEGALY:, 1. People with acromegaly have too much GH. It accelerates bone growth and organ enlargement., Because of this growth stimulation, the bones and organs of people with acromegaly are much, larger than other people’s bones and organs., 2. More than 95 percent of people with acromegaly have a benign tumour affecting their pituitary., This tumour is called an adenoma. Adenomas are common. They affect about 17 percent of, people. In most people, these tumors don’t cause excess GH, but when they do can result in, acromegaly., , 38, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 39 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , DIABETES INSIPIDUS:, Diabetes insipidus (DI) is a rare condition that occurs when your kidneys are not able to conserve water., SYMPTOMES OF DIABETES INSIPIDUS:, 1. The main symptoms of DI are excessive thirst, which can cause an uncontrollable craving for, water, and excessive urine volume., 2. A healthy adult will typically urinate less than 3 quarts of urine a day. People with DI may, eliminate up to 16 quarts of urine a day., 3. Fussiness and irritability, 4. Unusually wet diapers or bed-wetting, or excessive urine output, 5. Excessive thirst, 6. Dehydration, 7. High fever, 8. Dry skin, 9. Delayed growth, 10. Adults can experience some of the above symptoms, plus confusion, dizziness, or sluggishness., The four types of diabetes insipidus, CENTRAL DIABETES INSIPIDUS:, This is the most common form of DI and is caused by damage to the pituitary gland or hypothalamus., This damage means ADH cannot be produced, stored, or released normally. Without ADH, large, amounts of fluid are released into the urine., This type of DI is often the result of:, a. Head trauma, b. Diseases that cause brain swelling, 39, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 40 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , c. Surgery, d. Tumors, e. Loss of blood supply to the pituitary gland, f. Rare genetic conditions, NEPHROGENIC DIABETES INSIPIDUS:, Certain genetic defects can damage the kidneys, making them unable to respond to the ADH., Nephrogenic diabetes insipidus can also be caused by:, a. Medications, such as lithium or tetracycline, b. High levels of calcium in the body, c. Low potassium levels in the body, d. Chronic kidney disease, e. Urinary tract blockage, , CRETINISM:, Cretinism is a medical condition in which hypothyroidism occurs early in life. It is a disease of thyroid, gland where levels of thyroid hormones in the blood is low (hypothyroidism) since birth., If left untreated it can cause stunted physical and mental growth. It is also known as congenital, hypothyroidism., SYMPTOMS OF CRETINISM:, The signs and symptoms of cretinism can vary depending on age of onset., 1. Early signs of infancy, 2. Slow movement, 3. Development of dry skin, 40, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 41 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 4. Drooling from an open mouth, 5. Abnormal physical characteristics, 6. Short and wide face, 7. Low hair line, 8. Underdeveloped lower jaw, 9. Overdeveloped upper jaw, 10. Tongue which is thick, large and protruding (macroglossia), 11. Short and thickened bones, 12. Delayed eruption of the teeth, 13. Signs and Symptoms of Later Stages, 14. Retarded learning abilities, 15. Reduced intelligence, 16. Breathing difficulties, 17. Slow pulse, 18. Crying very little, Sometimes, the new born children can be of normal weight, height and without any symptoms so, screening tests are done usually., CAUSES OF CRETINISM:, There are many causes by which cretinism can develop and each cause affect the production of thyroid, hormones at one or the other level and includes, 1. Missing or misplaced thyroid gland: the thyroid gland which is responsible for the production, of thyroid hormones may be absent, underdeveloped or located at a different location. It is the, reason of about 85 % cases of cretinism., 2. Central hypothyroidism: this occurs due to some dysfunction of hypothalamus and pituitary it, is due to the defects in a hormone called as TSH which is produced by the pituitary and stimulates, , 41, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 42 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , the thyroid gland to produce thyroxine. Reduced levels of TSH hormone in blood causes less, release of thyroxine hormone and the child suffers from cretinism., 3. Maternal iodine deficiency: thyroid hormone is required by developing fetus and if mother is, taking diet less in iodine which is essential for the production of the thyroid hormones then the, baby will definitely suffer from cretinism., 4. Other hereditary causes: Sometimes the thyroid gland is present and still the child suffers from, cretinism. It is due to the fact that that there can be problems in other proteins and enzymes which, causes, a) Defects in thyroid hormone synthesis and secretion, b) Defects in the transport of the thyroid hormones from the thyroid gland to the different parts of, the body, c) Defect in the action of the thyroid hormone such that the body tissues do not respond to the, hormone, , GRAVE’S DISEASE:, Grave’s disease is an autoimmune disorder that results in increased production of thyroid hormones., Autoimmune disorders are those in which the immune system of the body attacks the cells of their own, body., SYMPTOMS OF GRAVES’ DISEASE:, The common symptoms of the disease are due to excess of thyroxine hormone and due to underline, autoimmune disease, 1. Restlessness, 2. Weight loss, 3. Weak tremors, 4. Irritability, 42, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 43 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 5. Enlargement of the thyroid gland (goiter) seen as swelling in the anterior neck., 6. Altered menstrual cycles in the women, 7. Reduced libido in men, 8. Increased heart rate and irregular heartbeat/ palpitation, 9. Graves’ ophthalmology: The immune system and inflammation affect muscles and, other tissue around the eyes. Every one out of three people suffering from Graves’ disease, suffers from this. Symptoms are Bulging eyes, Gritty sensation in the eyes, eye Pressure,, Redness, 10. Graves’ dermopathy: very Uncommon symptom, rudeness, and thickening of skin, occurs generally in the shin area., , CAUSES OF GRAVES’ DISEASE:, As told earlier it is an autoimmune disorder, your normal immune system produces antibodies to fight, against foreign pathogens such as bacteria, fungi, viruses but sometimes the immune system becomes, malfunctioned and starts forming antibodies against your own cell of the body. The mechanism behind, this autoimmunity is not known properly., The antibody produced in Graves’ disease is called a thyrotropin receptor antibody (TrAB). This, antibody behaves similarly to that pituitary hormone which tells the thyroid gland how much thyroxine, is to be produced., , GOITER:, A goiter is an abnormal enlargement of thyroid gland., The most common cause of goitres worldwide is a lack of iodine in the diet., , 43, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 44 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , SYMPTOMS OF GOITRE:, 1. A swelling at the base of your neck that may be particularly obvious when you shave or, put on makeup, 2. A tight feeling in your throat, 3. Coughing, 4. Hoarseness, 5. Difficulty swallowing, 6. Difficulty breathing, CAUSES FO GOITER:, Several things can cause your thyroid gland to enlarge. Some of the most common are:, 1. Iodine deficiency: Iodine is essential for the production of thyroid hormones, and is found, primarily in seawater and in the soil in coastal areas. In the developing world, people who live, inland or at high elevations are often iodine deficient and can develop goiter when the thyroid, enlarges in an effort to obtain more iodine. In countries where iodine is routinely added to table, salt and other foods, a lack of dietary iodine isn't usually the cause of goiter., 2. Graves' disease: A goiter can sometimes occur when your thyroid gland produces too much, thyroid hormone (hyperthyroidism). In someone who has Graves' disease, antibodies produced, by the immune system mistakenly attack the thyroid gland, causing it to produce excess, thyroxine. This overstimulation causes the thyroid to swell., 3. Hashimoto's disease: A goiter can also result from an underactive thyroid (hypothyroidism)., Like Graves' disease, Hashimoto's disease is an autoimmune disorder. But instead of causing, your thyroid to produce too much hormone, Hashimoto's damages your thyroid so that it, produces too little., , 44, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 45 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 4. Multinodular goiter: In this condition, several solid or fluid-filled lumps called nodules develop, in both sides of your thyroid, resulting in overall enlargement of the gland., 5. Solitary thyroid nodules: In this case, a single nodule develops in one part of your thyroid, gland. Most nodules are noncancerous (benign) and don't lead to cancer., 6. Thyroid cancer: Thyroid cancer is far less common than benign thyroid nodules. A biopsy of a, thyroid nodule is very accurate in determining whether it's cancerous., 7. Pregnancy: A hormone produced during pregnancy, human chorionic gonadotropin (HCG),, may cause your thyroid gland to enlarge slightly., 8. Inflammation: Thyroiditis is an inflammatory condition that can cause pain and swelling in the, thyroid. It may also cause the body to produce too much or too little thyroxine., , DIABETES MELLITUS:, DIABETES TYPES:, Diabetes mellitus, commonly known as diabetes, is a metabolic disease that causes high blood sugar., The hormone insulin moves sugar from the blood into your cells to be stored or used for energy. With, diabetes, your body either doesn’t make enough insulin or can’t effectively use the insulin it does make., There are a few different types of diabetes:, Type 1 diabetes is an autoimmune disease. The immune system attacks and destroys cells in the, pancreas, where insulin is made. It’s unclear what causes this attack. About 10 percent of people with, diabetes have this type., Type 2 diabetes occurs when your body becomes resistant to insulin, and sugar builds up in your blood., Prediabetes occurs when your blood sugar is higher than normal, but it’s not high enough for a diagnosis, of type 2 diabetes., Gestational diabetes is high blood sugar during pregnancy. Insulin-blocking hormones produced by, the placenta cause this type of diabetes., 45, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 46 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , SYMPTOMS OF DIABETES:, General symptoms: The general symptoms of diabetes include:, a. increased hunger, b. increased thirst, c. weight loss, d. frequent urination, e. blurry vision, f. extreme fatigue, g. sores that don’t heal, Symptoms in men: In addition to the general symptoms of diabetes, men with diabetes may have a, decreased sex drive, erectile dysfunction (ED), and poor muscle strength., Symptoms in women: Women with diabetes can also have symptoms such as urinary tract infections,, yeast infections, and dry, itchy skin., Type 1 diabetes:, Symptoms of type 1 diabetes can include:, 1. extreme hunger, 2. increased thirst, 3. unintentional weight loss, 4. frequent urination, 5. blurry vision, 6. tiredness, Type 2 diabetes:, Symptoms of type 2 diabetes can include:, 46, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 47 :
ZOOLOGY – DSE 1A, 1., , increased hunger, , 2., , increased thirst, , 3., , increased urination, , 4., , blurry vision, , 5., , tiredness, , 6., , sores that are slow to heal, , ENDOCRINOLOGY AND REPRODUCTON, , CAUSES OF DIABETES:, Different causes are associated with each type of diabetes., Type 1 diabetes:, For some reason, the immune system mistakenly attacks and destroys insulin-producing beta cells in the, pancreas., Genes may play a role in some people. It’s also possible that a virus sets off the immune system attack., Type 2 diabetes:, Type 2 diabetes stems from a combination of genetics and lifestyle factors. Being overweight or obese, increases your risk too. Carrying extra weight, especially in your belly, makes your cells more resistant, to the effects of insulin on your blood sugar., This condition runs in families. Family members share genes that make them more likely to get type 2, diabetes and to be overweight., Gestational diabetes:, Gestational diabetes is the result of hormonal changes during pregnancy. The placenta produces, hormones that make a pregnant woman’s cells less sensitive to the effects of insulin. This can cause high, blood sugar during pregnancy. Women who are overweight when they get pregnant or who gain too, much weight during their pregnancy are more likely to get gestational diabetes., , 47, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 48 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , CUSHING’S SYNDROME:, SYMPTOMES OF CUSHING’S SYNDROME:, 1. The most common symptoms of this condition are:, a. weight gain, b. fatty deposits, especially in the midsection, the face (causing a round, moon-shaped face),, and between the shoulders and the upper back (causing a buffalo hump), c. purple stretch marks on the breasts, arms, abdomen, and thighs, d. thinning skin that bruises easily, e. skin injuries that are slow to heal, f. acne, g. fatigue, h. muscle weakness, 2. In addition to the common symptoms above, there are other symptoms that may sometimes be, observed in people with Cushing’s syndrome., 3. These can include:, a. high blood sugar, b. increased thirst, c. increased urination, d. osteoporosis, e. high blood pressure (hypertension), f. a headache, g. mood swings, h. anxiety, i. irritability, j. depression, k. an increased incidence of infections, 48, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 49 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 4. In children: Children can have Cushing’s syndrome too, although they develop it less frequently, than adults. In addition to the symptoms above, children with Cushing’s syndrome may also, have:, a. obesity, b. slower rate of growth, c. high blood pressure (hypertension), 5. In women: Cushing’s syndrome is more prevalent in women than in men. According to the, National Institutes of Health (NIH), three times as many women develop Cushing’s syndrome, compared to men., Women with Cushing’s syndrome may develop extra facial and body hair., This most often occurs on the:, a. face and neck, b. chest, c. abdomen, d. thighs, Additionally, women with Cushing’s syndrome may also experience irregular menstruation. In some, cases, menstruation is absent altogether. Untreated Cushing’s syndrome in women can lead to, difficulties becoming pregnant., 6. In men: As is the case with women and children, men with Cushing’s syndrome can also, experience some additional symptoms., Men with Cushing’s syndrome may have:, a. erectile dysfunction, b. a loss of sexual interest, c. decreased fertility, , 49, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 50 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , CAUSES OF CUSHING’S SYNDROME:, 1. Cushing’s syndrome is caused by an excess of the hormone cortisol. Your adrenal glands, produce cortisol., 2. It helps with a number of your body’s functions, including:, a. regulating blood pressure and the cardiovascular system, b. reducing the immune system’s inflammatory response, c. converting carbohydrates, fats, and proteins into energy, d. balancing the effects of insulin, e. responding to stress, 2. Body may produce high levels of cortisol for a variety of reasons, including:, a. high stress levels, including stress related to an acute illness, surgery, injury, or, pregnancy, especially in the final trimester, b. athletic training, c. malnutrition, d. alcoholism, e. depression, panic disorders, or high levels of emotional stress, 2. Corticosteroids: The most common cause of Cushing’s syndrome is the use of corticosteroid, medications, such as prednisone, in high doses for a long period. Healthcare providers can, prescribe these to treat inflammatory diseases, such as lupus, or to prevent rejection of a, transplanted organ., 3. High doses of injectable steroids for treatment of back pain can also cause Cushing’s syndrome., However, lower dose steroids in the form of inhalants, such as those used for asthma, or creams,, such as those prescribed for eczema, usually aren’t enough to cause the condition., 4. Tumors: Several kinds of tumors can also lead to a higher production of cortisol., Some of these include:, , 50, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 51 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , a. Pituitary gland tumors. The pituitary gland releases too much adrenocorticotropic, hormone (ACTH), which stimulates cortisol production in the adrenal glands. This is, called Cushing’s disease., b. Ectopic tumors. These are tumors outside of the pituitary that produce ACTH. They, usually occur in the lung, pancreas, thyroid, or thymus gland., c. Adrenal gland abnormality or tumor. An adrenal abnormality or tumor can lead to, irregular patterns of cortisol production, which can cause Cushing’s syndrome., , ADISON’S DISEASE:, Addison’s disease occurs when the adrenal cortex is damaged, and the adrenal glands don’t produce, enough of the steroid hormones cortisol and aldosterone., Cortisol regulates the body’s reaction to stressful situations. Aldosterone helps with sodium and, potassium regulation. The adrenal cortex also produces sex hormones (androgens)., SYMPTOMES OF ADDISON’S DISEASE:, People who have Addison’s disease may experience the following symptoms:, a. muscle weakness, b. fatigue and tiredness, c. darkening in skin colour, d. weight loss or decreased appetite, e. a decrease in heart rate or blood pressure, f. low blood sugar levels, g. fainting spells, h. sores in the mouth, i. cravings for salt, , 51, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 52 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , j. nausea, k. vomiting, 2. People living with Addison’s disease may also experience neuropsychiatric symptoms, such as:, a. irritability or depression, b. lack of energy, c. sleep disturbances, 3. If Addison’s disease goes untreated for too long, it can become an Addisonian crisis. Symptoms, associated with an Addisonian crisis can include:, a. agitation, b. delirium, c. visual and auditory hallucinations, 4. An Addisonian crisis is a life-threatening medical emergency and begins to experience:, a. mental status changes, such as confusion, fear, or restlessness, b. loss of consciousness, c. high fever, d. sudden pain in the lower back, belly, or legs, CAUSES OF ADDISON’S DISEASE:, There are two major classifications for Addison’s disease: primary adrenal insufficiency and, secondary adrenal insufficiency., Primary adrenal insufficiency:, Primary adrenal insufficiency occurs when your adrenal glands are damaged so severely that they can, no longer produce hormones. This type of Addison’s disease is most often caused when your immune, system attacks your adrenal glands. This is called an autoimmune disease., In an autoimmune disease, body’s immune system mistakes any organ or area of the body for a virus,, bacteria, or another outside invader., , 52, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 53 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , Other causes of primary adrenal insufficiency include:, •, , prolonged administration of glucocorticoids (e.g. prednisone), , •, , infections in your body, , •, , cancer and abnormal growths (tumors), , •, , certain blood thinners used to control clotting in the blood, , Secondary adrenal insufficiency:, Secondary adrenal insufficiency occurs when the pituitary gland (located in your brain) can’t produce, adrenocorticotropic hormone (ACTH). ACTH tells the adrenal glands when to release hormones., It’s also possible to develop adrenal insufficiency if you do not take the corticosteroid medications your, doctor prescribes. Corticosteroids help control chronic health conditions like asthma., There are also many other causes of secondary adrenal insufficiency, including:, •, , tumors, , •, , medications, , •, , genetics, , •, , traumatic brain injury, ******, , 53, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 54 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , UNIT – IV, REPRODUCTIVE PHYSIOLOGY, , FUNCTIONAL MORPHOLOGY OF MAMMALIAN TESTIS:, , 1. Testis are the primary sex organ in males and are extra abdominal in position., 2. There is a pair of testis measuring the size of 4.5 cm x 2.5 cm x 3 cm, oval in shape and pink, in colour., 3. Testes is lodged in a thin walled skin pouch called scrotum or scrotal sac. Scrotal sac is tilled, with a tissue fluid called as hydrocoel. Testes is held in the scrotal sac by thick fibrous tissue, called spermatic cord., , 54, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 55 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 4. The reason for extra abdominal position of testis is that testicular temperature should be 2°C, lower than the body temperature for normal spermatogenesis to occur. Rise in temperature, kills spermatogenetic tissues., 5. Outer most cover of testes is called as tunica vaginali, under this there is a dense fibrous cover, called as tunica albuginea and inner to this coat there is a loose connective tissue and blood, vessels which together form the tunica vasculosa., 6. Internally tunica albuginea divides each testis into 200-300 lobules. Each of these lobes consists, of 1—3 convoluted seminiferous tubules. Each testes consists of 1000 seminiferous tubules., 7. Seminiferous tubules are a tubular structure which has both the ends terminating into short, tubules called tubular recti. Tubular recti connect seminiferous tubules to rete testis., , 8. There are two kinds of cells found in seminiferous tubules. They are spermatogenic cells, (germ cells) and Sertoli or supporting cells (nurse cells)., 9. Germ cells form the spermatozoa by spermatogenesis and Sertoli cells provide nourishment, to the developing sperm., 10. Between the seminiferous tubules, Leydig cells are found. These are polygonal in shape and, secrete a male steroid hormone called testosterone., , 55, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 56 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , FUNCTIONAL MORPHOLOGY OF MAMMALIAN OVARY:, , 1. There are pair of ovaries present on either side of the uterus in the abdominal cavity. Each, ovary is almond in shape and the size is 3.5 cm long, 2 cm wide and 1 cm thick., 2. Each ovary is lined by cuboidal germinal epithelium, below the germinal epithelium lies a, layer of connective tissue called tunica albuginea., 3. Inner to the tunica albuginea is stroma. Stroma is further divided into dense outer cortex and, less dense inner medulla., 4. Many Graafian follicles/ovarian follicles are present in the cortex and show different stages of, development., , 56, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 57 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 5. Initial stage of development is primary oocyte. As the primary oocyte develops it changes to, secondary oocyte. Secondary oocyte is released from the ovary by the rupturing of ovarian, wall. This process is known as ovulation., , 6. There are around four lakh follicles in both the ovaries of an adult woman. Most of the follicles, disappear by phagocytosis during reproductive years. This process is called follicular atresia., Due to this a female produce only around 450 ova in her entire reproductive life which ends, between 40 and 50 years of age., , 7. Secondary oocyte surrounded by layers of follicular cells is called as Graafian follicle. It is, suspended in the antrum which is filled with semi-viscous fluid called liquor folliculi, secreted, by follicular cells., , 8. Follicular cells act as endocrine cells and secrete hormone oestrogen in blood., , 9. Cortex of ovary also consists of conical, yellowish cells known as corpus luteum which on, degeneration is called as corpus albicans. Corpus luteum also functions as endocrine cells and, secretes progesterone, oestrogen and relaxin., , 57, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 58 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , GONADAL HORMONES:, , MALE GONADAL HORMONE:, , A pair of testes is situated in the scrotum of male. The connective tissue present between the, seminiferous tubules in a testis contains small clusters of endocrine cells called interstitial cells or, Leydig’s cells. These cells secrete various male sex hormones called androgens. The principal androgen, is testosterone., , TESTOSTERONE:, , It is the chief male sex hormone. It is mainly secreted from Leydig cells and to some extent from, Sertoli cells of testis., , The functions of testosterone are given below:, , 1. Effects on growth of seminiferous tubule and spermatogenesis: It helps in growth and, maturation of seminiferous tubule. It also stimulates the formation of spermatogonia from, primordial germ cells., 2. On sex organs and glands: It stimulates the growth and functions of epididymis, penis,, prostate gland, and seminal vesicle. The synthesis of RNA, specific structural and enzymatic, proteins is stimulated by this hormone. The prostate and seminal vesicles secrete fructose which, acts as nutritive material for the spermatozoa., 3. Effects on secondary male sex characters: It helps to develop and maintain the secondary sex, characters like beards, moustache, masculine voice, distribution of hairs on chest, pubis, back, etc. and distribution of pigments on the skin., 4. Anabolic effects: It increases the synthesis of muscle proteins for well-built musculature. It, also increases the Ca++ deposition in bones., 5. On blood: It increases haemoglobin content in blood., 58, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 59 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 6. On metabolism: It increases BMR., 7. On skin: It increases the thickness of skin and also increases secretion of sebum from, sebaceous gland., 8. On behaviour: It produces aggressive behaviour and interest in the opposite sex., , FEMALE GONADAL HORMONE:, , In the female the ovaries are located in the pelvic cavity in close proximity to the oviducts and the uterus., The hormones produced by the ovaries include oestrogens, progesterone, relaxin and inhibin/actin., , ESTROGEN:, , It is a female sex hormone, majorly produced in the ovary by the growing follicle cells., , Functions of oestrogen are given below:, , 1. On ovary: It has a direct stimulatory effect on the follicular growth., 2. On female sex characters: It helps to stimulate the growth of breast, uterus and vagina at, puberty. It changes the vaginal epithelium. The external genitalia become enlarged by the effect, of oestrogen with the deposition of fat., 3. On secondary female sex characters: It helps in deposition of subcutaneous fat, especially in, breast and buttocks. It leads to the development of feminine voice, narrow shoulder and broad, hips., 4. On mammary glands: It primarily stimulates the growth of an extensive ductile system of, mammary gland., 5. Anabolic effect: It promotes retention of sodium, calcium and phosphates in the body. It causes, uptake of Ca++ from bones., 6. On reproductive cycle: The physiologic levels of oestrogen promote the pituitary release of LH, for ovulation., , 59, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 60 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , PROGESTERONE:, , It is another female sex hormone. It is chiefly secreted from corpus luteum., , The functions of progesterone are given below:, , 1. On uterus: It promotes secretory changes in the endometrium of the uterus and prepares the, uterus for implantation of fertilized ovum., 2. On placenta: During pregnancy, it helps to maintain the placenta, as well as gestation., 3. On mammary gland: It helps in the proliferation of alveolar system of mammary gland for, secretion., 4. On ovarian follicles: This hormone inhibits follicular maturation during pregnancy., 5. On body temperature: It is thermo-genic and is usually responsible for the rise in basal, temperature at the time of ovulation., , RELAXIN:, , It is secreted by the corpus luteum only during the later stages of pregnancy and helps to soften, ligaments, especially those that hold the pubic symphysis together. It may also affect other ligaments,, e.g., if it affects a woman’s foot ligaments, she may experience an increase in shoe size following, pregnancy., , INHIBIN / ACTIN:, Inhibin/actin is secreted by the corpus luteum. Inhibin hormone inhibits and actin hormone activates, the FSH and GnRH production., , 60, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 61 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , MALE ACCESSORY REPRODUCTIVE ORGANS AND ITS ROLE:, , Male reproductive system consists of following parts:, 1. Testes: There is a pair of testis lodged in a thin walled skin pouch called scrotum or scrotal, sac. Testes are extra abdominal. The reason behind this is that testicular temperature should be, 2°C lower than the body temperature for normal spermatogenesis to occur. Internally tunica, albuginea divides each testis into 200-300 lobules. Each of these lobes consists of 1—3, convoluted seminiferous tubules. Each testes consists of 1000 seminiferous tubules. There, are two kinds of cells found in seminiferous tubules; spermatogenic cells (germ cells) and, Sertoli or supporting cells (nurse cells). Germ cells form the spermatozoa by spermatogenesis, and Sertoli cells provide nourishment to the developing sperm. Between the seminiferous, tubules, Leydig cells are found, they secrete a male steroid hormone called testosterone., , 2. Vasa Efferentia: Rete testes gives rise to 10-20 ductules called as vasa efferentia. Vasa, efferentia enters the head of epididymis. They are lined by pseudo stratified epithelium which, helps in sperm movement., 61, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 62 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 3. Epididymis: It is a 6-metre-long coiled tube found in the poster lateral side of each testes. It is, divided into three parts:, , Upper caput epididymis: This part is wide and receives vasa efferentia., , Middle Corpus epididymis: It stores sperms for a short duration, which undergoes, maturation. It lies in the lateral side of testes., , Lower Cauda epididymis: Before entering the vas deferens the spermatozoa is stored here. This, part lies on the caudal side of the testes and is wide., , 4. Vas Deferentia: This is also called as seminal duct. It is around 30 cm long, narrow, muscular, and tubular structure which starts from the tail of epididymis, passes through the inguinal, canal, then over the urinary bladder and then joins the duct of seminal vesicle to form a 2 cm, long ejaculatory duct. After passing through the prostate gland it joins the urethra. Before the, sperms are transferred to urethra they are stored in spindle like ampulla of vasa deferens., , 5. Penis: It is the male genetalia. It is erectable, copulatory, cylindrical organ. It is made up of, three erectable tissues. Two of the three are posterior and made of yellow fibrous ligament and, is called as Corpora cavernosa. One is anterior, spongy and highly vascular Corpus, spongiosum. It surrounds the urethra. The tip of penis is highly sensitive and is called glans, penis. There is a retractile fold of skin on glans penis and is known as fore skin or prepuce. The, erection of penis is due to rush of arterial blood into sinuses of corpus spongiosum., , 6. Seminal Vesicle: They are convoluted, glandular sacs of 4 cm length. It provides seminal, fluid, which is alkaline and viscous. It contains fructose and prostaglandins. Fructose provides, energy to the sperms for swimming and prostaglandins stimulate vaginal contraction which helps, in the fusion of gametes., , 62, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 63 :
ZOOLOGY – DSE 1A, , 7., , ENDOCRINOLOGY AND REPRODUCTON, , Pair of Cowper’s Gland (Bulbourethral gland): These are pea seed sized, white in colour, and located at the base of penis. Its secretion helps in lubrication of vagina for smooth, movement of penis during copulation., , 8. Prostate Gland: It surrounds the proximal part of urethra. It is large and lobulated. It pours, alkaline secretion through 20-30 openings. This secretion contains lipids, bicarbonate ions,, enzyme and small amount of citric acid. The secretion of accessory sex glands, i.e. prostate, gland and mucus from seminal vesicles combine with sperm to form seminal fluid or semen., The pH is alkaline, i.e. 7.3 – 7.5., , FEMALE ACCESSORY REPRODUCTIVE ORGANS AND ITS ROLE:, Following parts constitute the female reproductive system, a pair of ovaries, fallopian tube, uterus,, cervix, vagina and accessory genital glands and a pair of mammary glands., , 1. Pair of Ovaries: Each ovary is almond-shape of the size is 3.5 cm long, 2 cm wide and 1 cm, thick. It is placed in the abdominal cavity. Many Graafian follicles/ovarian follicles are present, , 63, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 64 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , in the cortex and show different stages of development. Initial stage of development is primary, oocyte. As the primary oocyte develops it changes to secondary oocyte., Secondary oocyte is released from the ovary by the rupturing of ovarian wall. This process is, known as ovulation. Secondary oocyte surrounded by layers of follicular cells is called as, Graafian follicle., , 2. Fallopian Tube or Oviduct: Fallopian tube is around 10 cm long, muscular, tubular and, ciliated structure. It lies in pelvic region, just above the urinary bladder. A viscous liquid is, secreted by secretory cells, which provides protection and nourishment to the ovum. Ciliated, cells help in the movement of ovum. Each fallopian tube is divided into infundibulum,, ampulla, isthmus and uterine part., , 3. Uterus: It is hollow, muscular, vascular and large (8 cm x 5 cm x 2 cm) pear shaped structure,, which is present in the pelvic region above the bladder. It can be divided into three parts –, fundus, body and cervix. Fundus is upper, dome shaped part above the opening of fallopian, tube. The middle and major part of uterus is the body. It has three layers – outer peritoneal, perimetrium, middle muscular myometrium and highly vascular endometrium. The lower, narrow part which opens in the body of the uterus by internal opening and in vagina by external, opening is called cervix. Uterus is the site of foetal placentation, its growth and parturition., , 4. Vagina: This is a tubular structure, 10-12 cm long and extends from cervix to the outside of, body. It receives the sperms during copulation, is passage for menstrual flow and forms the, birth canal during labour. Hymen is the membranous structure which covers the opening of, vagina – the vaginal orifice. Vagina is lined by non-keratinised stratified squamous epithelium., Glands are absent in vaginal wall., , 5. Vulva: This is the external genitalia of females. It consists of the vestibule or urino-genital, sinus which is in the form of depression and is in the front of anus. It has two apertures, upper, , 64, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 65 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , external urethral orifice and lower vaginal orifice. The anterior part is fatty and covered with, pubic hair. This portion is called as Mons pubis., , Corresponding to the male penis, clitoris is present in the females which is made of erectile, tissue. Two large, thick- walled fold of skin form the boundary of vulva. These are labia major, and contain sebaceous glands. Between labia major two small folds are present and are called as, labia minora. Labia minora fuse posteriorly to form fourchette., 6. Bartholin’s gland: On either side of vaginal orifice there is a pair of Bartholin’s gland. This, gland secretes a clear, viscous fluid which works as lubricating agent during copulation. The, area below fourchette and anus is perineum., 7. Mammary Gland or Breast: In human beings’ mammary glands are one pair and present on, ventral thoracic wall. They are modified sweat glands. In males it is rudimentary whereas in, females it is well developed., , 65, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 66 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , The breast is externally covered with skin and in the centre there is nipple made of erectile tissue., Nipple is surrounded by pigmented area called areola. Areola has numerous sebaceous glands called, areolar gland., , Human milk is made of organic, inorganic compounds and water. Milk is poor in iron. It mainly, consists of fat droplets, lactase, casein, vitamins and minerals like sodium, potassium, calcium,, phosphate, etc. Glandular, fibrous and adipose tissues constitute the mammary glands., , a) Glandular Tissue: This tissue consists of around 20 lobes and each lobe has 15-20, lobules. Each lobule is made of group of glandular alveoli and unit to form lactiferous, duct. These ducts expand to form lactiferous sinuses which store milk during lactation., Each sinus opens to the outside by narrow ducts which are 0.5 mm in diameter., , b) Adipose Tissue: The surface of gland is covered by adipose tissue. It is also found, between the lobes. The size of the breast is determined by adipose tissue., , c) Fibrous Tissue: Glandular tissues and ducts get support from this tissue., , HUMAN MENSTRUAL CYCLE:, It is a series of cyclic changes occurring in the reproductive tract of female with the periodicity of 28, days. It is also known as ovarian cycle or endometrial cycle., It occurs from puberty to menopause., The initiation of first menstrual cycle is menarche and the cessation of menstrual cycle is known as, menopause., It is characterized by loss of vaginal blood (breaking of endometrium wall of uterus), The cycle is under Influenced of hormones secreted by pituitary gland (FSH and LH), and, ovary (progesterone and oestrogen)., , 66, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 67 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , The cycle has been divided into three important phases of events for the understanding; Menstrual, phase, Proliferative phase or follicular or ovulatory phase and Luteal or secretory phase, , 1. Menstrual phase:, a) This phase is characterized by discharge of blood, connective tissues and mucus due to, cast off of epithelial lining of endometrium wall, b) It Lasts for 3-5 days, c) Ovum remain unfertilized, d) At this time level of oestrogen and progesterone is very low in blood resulting in breaking, of endometrium wall of uterus, e) About 50-100 ml blood with mucus are discharges as menstrual flow., , 2. Proliferative phase, a) This phase is characterized by rapid proliferation and repair of damaged endometrium wall., b) It Lasts for 9-10 days (5th – 14thdays)., , 67, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 68 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , c) Anterior pituitary gland releases Follicular Stimulating Hormone (FSH) which stimulates, development and maturation of Graafian follicle. So, it is also known as Follicular Phase., d) Mature Graafian follicles secrete oestrogen. Its level gradually increases and maximize at, 12thday., e) Oestrogen stimulates endometrium repair and proliferation. It also stimulates Ovulation., f) Endometrium becomes 2-3 mm thick and highly vascular., , 3. Luteal phase:, a) This phase is characterized by release of Ovum from mature Graafian follicle which is, stimulated by the secretion of luteinizing hormone (LH) by pituitary gland., b) It Lasts for 12-14 days (14th-28th day), c) LH along with FSH stimulates ovulation., d) Mature Graafian follicle release ovum and the rapture follicular cell form corpus luteum., e) Corpus luteum secretes progesterone, high level of progesterone inhibit maturation of any, other follicles., f) Progesterone also stimulate thickening of endometrium wall., g) When ovum remain unfertilized, corpus luteum degenerate; level of both hormone, (progesterone and oestrogen) decreases, causing breaking of endometrium wall continuing, the menstrual phase., , ROLE OF HORMONES IN MENTRUAL CYCLE:, The process of oogenesis is controlled by three endocrine glands – hypothalamus, anterior pituitary, gland and ovaries., , The hormones released are Gonadotropin Release Hormone from hypothalamus, Follicle, Stimulating hormone and Luteinizing hormone secreted by anterior pituitary and Oestrogen and, Progesterone from the ovaries., , 68, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 69 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , The role of the hormones can be understood by following the normal monthly menstrual cycle of, development of ovum and the physical events in the menstrual cycle., , The sequence is as follows:, , a. Controlling centre of menstruation and ovulation is the hypothalamus. It releases GnRH,, which stimulates the release of FSH and LH from the anterior pituitary., b. FSH initiates the development of the oocyte within one of the immature ovarian follicles., c. Ovarian follicle produces Oestrogen, which causes the build-up of endometrium as well as, the inhibition of further production of FSH., d. The increased level of oestrogen stimulates the anterior pituitary to secrete LH, which helps, in enlarging the mature follicle and releases the secondary oocyte. It also helps in changing, the collapsed follicle into corpus luteum, an endocrine body., e. Oestrogen and Progesterone are secreted by corpus luteum. This helps in completing the, development of endometrium. If the oocyte is not fertilised and not implanted in the, endometrium, the corpus luteum disintegrates and is known as corpus albicans and thus,, oestrogen and progesterone secretion is stopped., , 69, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 70 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , f. Without progesterone and oestrogen, the endometrium breaks down and menstruation, occurs., g. The level of progesterone decreases further and the level of LH drop off too. This decrease in, LH causes pituitary to start secretion of FSH, which stimulates the development of another, ovum. The cycle begins again., , PRECOCIOUS PUBERTY OR EARLY ONSET OF PUBERTY:, , Precocious puberty is when a child's body begins changing into that of an adult (puberty) too soon. When, puberty begins before age 8 in girls and before age 9 in boys, it is considered precocious puberty., , Puberty includes rapid growth of bones and muscles, changes in body shape and size, and, development of the body's ability to reproduce., , The cause of precocious puberty often can't be found. Rarely, certain conditions, such as infections,, hormone disorders, tumors, brain abnormalities or injuries, may cause precocious puberty. Treatment, for precocious puberty typically includes medication to delay further development., , SYMPTOMS:, Precocious puberty signs and symptoms include development of the following before age 8 in girls and, before age 9 in boys., , , Breast growth and first period in girls, , , , Enlarged testicles and penis, facial hair and deepening voice in boys, , , , Pubic or underarm hair, , , , Rapid growth, , , , Acne, , , , Adult body odour, , 70, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 71 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , CAUSES:, To understand what causes precocious puberty in some children, it's helpful to know what causes puberty, to begin. The brain starts the process with the production of a hormone called gonadotropin-releasing, hormone (GnRH)., When this hormone reaches the pituitary gland —it leads to the production of “more” hormones in the, ovaries for females (Oestrogen) and the testicles for males (testosterone)., , Oestrogen is involved in the growth and development of female sexual characteristics. Testosterone is, responsible for the growth and development of male sexual characteristics., , FOOD:, , Studies show that, consuming chicken, beef, fast food, French fry, and soft drink intake were, significantly correlated with both early breast and pubic hair development. There was a significant, relationship between chicken consumption., , It was deduced from various research studies that the increased consumption of meat intake is a major, nutritional factor associated with the early occurrence of menarche. A definite link between the, consumption of meat by young women and the early onset of menstruation has been reported., , A greater consumption of animal protein between the ages of 3 and 7 years results in a greater, likelihood of menarche before the age of 12 years., , A British study also demonstrated that a high consumption of animal protein in childhood is positively, associated with earlier menarche age., , In an Italian study, the possible nutritional factors triggering puberty at a younger age were determined., The study was conducted on school meals containing beef and poultry products to analyse the effects, , 71, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 72 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , on school children. These food products were found to possess residues of steroid hormones, which, were suggested as a potential reason for breast enlargement in pupil at a very young age., , It is elaborated that intake of cola drink, beef, French fries and other junk foods excessively in the, daily diet are the underlying reasons of increasing obesity among girls resulting early puberty., , It was concluded that unbalanced nutrition has been a major cause of early maturation in the young, girls. It is therefore highly recommended to take healthy nutrition with lower quantities of meat., , LIFESTYLE:, , The sedentary mode of childhood increases the body mass indices (BMIs) were significantly correlated, with the age at menarche, indicating that the age at menarche is lower with higher BMIs., , The obesity epidemic particularly in children and teenagers is found to be a triggering factor for early, hormonal alterations in girls., , With the improved life style, the usage of various cosmetics, rain coat, hair spray, toys, etc. also become, part and parcel of the life. These, contain harmful chemical substances like Phthalate, Bisphenol A, (BSA), which are also responsible for the precocious puberty., , *******, , 72, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 73 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , UNIT – V, MODERN TRENDS IN HUMAN REPRODUCTION, , A. FERTILITY CONTROL:, POPULATION EXPLOSION:, , Population explosion is not only a problem in India; it has reached a menacing proportion all over the, world, especially in the poorer countries., , The population of India was around 361 million during the census of 1951. It reached over 1.21 billion, during the census of 2011., , Some statistics relating to population growth indicate that by 2022, the population of India is likely to, pass the 1.5 billion mark. Thus, there is no denying that India is currently experiencing a population, explosion., , MEANING OF POPULATION EXPLOSION:, , Population Explosion refers the sudden and rapid rise in the size of population, especially human, population., , It is an unchecked growth of human population caused as a result of: Increased birth rate, Decreased, infant mortality rate, and Improved life expectancy., , A drastic growth in population beyond normal limits is called population explosion. It is more, prominent in under-developed and developing countries than in developed countries. Population, explosion mainly refers to the surge in population post-World War II. However, in context to India, it, refers to the rapid increase in population in post-Independent era., 73, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 74 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , CAUSES: The causes of population explosion are as follows:, , 1., , Accelerating birth rate: Due to lack of awareness about the positive impact of using birthcontrol method, there has been a steady growth in birth rate., , 2., , Decrease in infant mortality rate: An improvement in medical science and technology, wide, usage of preventive drugs (vaccines), has reduced the infant mortality rate. There has been great, improvement in medical and health-care facilities during the past few decades., , 3., , Increase in life expectancy: Due to improved living conditions, better hygiene and sanitation, habits, better nutrition, health education, etc. the average life expectancy of human population, has improved significantly. Steady supply of good quality food makes sure that the population, is well nourished. Populations grow when they are adequately nourished., , 4., , Increased immigration: An increase in immigration often contributes towards population, explosion, particularly in developed countries. It happens when a large number arrive at an, already populated place with the intention to reside permanently., , 5., , Less space than required: In urban cities, it is often found that there is very less scope for, making available extra space to absorb the additional population. In such cases, a large, population is seen packed into a smaller space., , EFFECTS: The effects of population explosion in India are as follows:, , 1. Over-population: Population explosion may lead to overpopulation, i.e., a condition where, population surges to a level that the earth cannot accommodate comfortably, and poses a threat, to the environment., 2. Unemployment: In developing countries like India, with a backward economy and little scope, for fruitful employment, millions of people find no work to do. The unemployed, having nothing, to do and without an ensured living, are left frustrated and demoralize, losing their faith in life, itself., 74, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 75 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 3. Poverty: High birth rate, both historically and statistically, is associated with poverty and low, standard of living. It may be noted that poverty is both the cause and effect of population, explosion. Due to poverty, there has been massive growth of population. On the other hand, the, large masses of people live in poverty due to overpopulation., 4. Illiteracy: The resources available are fixed. In theory and in practice, the total available, resources are shared by the people using them. Population explosion is the key reason for, illiteracy in India. People prefer engage their children in economic activities, rather than, providing them education., 5. Poor Health: If people do not get adequate food and nutrition, then they may suffer from poor, health., 6. Economy: People need food, clothes, shelter, and occupation to make their living. The demand, for consumption should never exceed the production or resource limit. The economy of any, country is negatively impacted, if there is massive population explosion beyond the tolerance, limit., 7. Pollution and Global warming: Too much population causes too much pressure on earth. There, arises excessive demand for finished products leading to over-industrialization and overutilization of resources. The industrial discharges and fumes are the chief causes for water and, air pollution. Further, the poisonous gases released because of burning of fossil fuels in factories, are widely responsible for Global warming., , NEED FOR BIRTH CONTROL IN INDIA:, , The awareness made our governments, both at the centre and in the states, to think about the adopt, official programme to educate public opinion and reduce the birth rate so that the population can fit in, well with the evolving pattern of developing economy., , The Family Planning as an official programme was launched with much fanfare in 1952. The, government is still trying to educate the people. All government agencies and institutions mobilized all, their resources to attain the goal of planned families., 75, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 76 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , The people were reminded of the advantages of small families, of healthy and happy children and of the, need for eradicating the age-old poverty. The parents were persuaded to go in for sterilization after, the births of two children, for the contraceptive were not always found to be safe and full-proof., , Many parents, especially the educated, came forward to see things in the new light and were amenable, to persuasion. However, many others resisted, at places quite violently, and refused to see reason., , The government was very serious about making the programme a success. The state governments also, came forward to help the centre in its bid to achieve success. Cheap contraceptives were distributed in, even the remotest villages, sex education was popularized, vasectomy operations were conducted and, abortion was legalized., , However, even then family planning has a lot more to achieve, for the population in India has already, become about 121 billion and at this rate of growth it may very soon become 150 billion and then 200, billion and so on., , The problem of population can be solved only by creating awareness and educating the people to control, birth rates. The advantages of adopting to various birth control methods should be properly explained to, common people., , Therefore, there is need for birth control in India to achieve the following important aspects;, , i., , Population explosion has caused more pressure on earth., , ii., , We should save energy so that the entire population can enjoy its benefit., , iii., , We can control the global warming issues by curbing the usage of fossil fuels., , iv., , Food security is another area that needs attention., , v., , The agricultural output should increase with growing population to make sure steady, supply of food to all., , 76, , vi., , We should use potable water carefully., , vii., , With larger population, there is a need for harmony and peace among nations., LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 77 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , CONTRACEPTIVE DEVICES:, , Contraceptive methods are preventive methods to help women avoid unwanted pregnancies., The contraceptive methods may be broadly grouped into two classes – the spacing or temporary, methods and the terminal or permanent methods., , The term contraception and fertility control are not synonymous. Fertility control includes fertility, inhibition or contraception and fertility stimulation. Contraception includes temporary and permanent, measures to prevent pregnancy., , An ideal contraceptive should be safe, effective, acceptable, inexpensive, reversible, simple to, administer, long lasting and should require minimal medical supervision. But there can never be an, ideal contraceptive. This is because what is suitable to one group may be unsuitable to another due to, different cultural patterns, religious beliefs and socio-economic milieu., , So the search for an ideal contraceptive has been given up. The present approach in family planning is, to provide the user a variety of choice from which he may choose according to his needs and wishes and, to promote family planning as a way of life. When properly provided and used, currently available, contraceptives are safe and effective for the vast majority of users., , A. Spacing or Temporary Methods: The spacing methods are commonly used to postpone or, space births. These methods are commonly used by couple who do not desire to have children., The temporary methods are of the following types:, , a. Barrier Methods:, , The aim of the barrier methods is to prevent the live sperm from meeting the ovum., Barrier methods suitable for both men and women are available. They have contraceptive, and non-contraceptive advantages., 77, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 78 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , The main contraceptive advantage is the absence of side effects and the non-contraceptive, advantage is the protection from sexually transmitted diseases or STD. These methods, prevent sperm deposition in the vagina or prevent sperm penetration through the, cervical canal. This is achieved by mechanical devices or by chemical or combined means., , i., , Physical or Mechanical Methods: The mechanical methods include the condoms for, males and diaphragm for females., , Condoms: Condoms are the most widely used barrier device by males and popularly, known as ‘Nirodh’ which in Sanskrit means prevention. The condom prevents the semen, from being deposited in the vagina and protects both men and women from STD., , Male Condom, In this, a thin rubber or latex sheath (condom) is rolled on the erect penis before, intercourse. It prevents semen (sperms) from entering the woman. The method is 95%, effective if used correctly. It can be used by all age groups, safely. No prior medical, examination is required and is easily available without, prescription. It serves as the most effective method in, providing twin protection of contraception and STI, disease. There are disadvantages intrinsic to this, method, as it may tear or slip if not used properly., Expired or perforated condoms should not be used., Female Condom, This is a vaginal pouch made of latex sheath, with, one ring at each end. The closed end ring is inserted, inside the vagina and works as the internal anchor., Outer portion covers and protects the external, genitalia. It is reliable, hypo-allergic with high acceptance in test groups although its cost, could be a major deterrent to use. It is a female controlled method and protects from both, 78, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 79 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , unwanted pregnancy and STDs. Size and hardness of inner ring may be uncomfortable, to some users. Extensive promotion and persuasion among female users is required to, make it popular., , Diaphragm and Spermicides (Barrier/Chemical Method), A soft rubber cap is fitted into the vagina shortly before the intercourse, to cover the, cervix, thus preventing sperms from entering the uterus. It must be left in place for at, least 6 h after intercourse. The, method is much more effective,, when used in combination with a, spermicidal cream to inactivate the, sperms. It does not interrupt lovemaking and can be used a few hours, before intercourse. Insertion and, removal are simple, once learnt from, the doctor and there are no complications after use. The user must use additional, spermicides if more than 3 h elapse between insertion and intercourse. The cap must be, inserted before every intercourse. Different sizes suit different women and a correct size, should be used. Size may change after childbirth or if there is weight gain or loss of more, than three kilograms and so, must be checked every 6 months. Medical assistance is, necessary to select right size and learn how to insert and remove it., , ii., , Chemical Methods: Various spermicidal agents are available in the market either in the, form of spermicidal cream, jelly or tablets. These agents produce sperm immobilisation, and kill the sperms. But these are not popular and the failure rate is quite high. Also,, concern about possible teratogenic effects on foetuses has been suggested. There may be, occasional local allergic reactions in the vagina., , 79, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 80 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , b. Natural Contraception:, , i., , Rhythm method of natural contraception is a method based on identification of the, fertile period (between the 13th and 18th days of the menstrual cycle) of a cycle and, to abstain from sexual intercourse during that period., , ii., , Coitus interruptus involves withdrawal of penis from the vagina just before, ejaculation, thus preventing semen from entering the woman. This is perhaps the, oldest contraceptive method known to man, but it depends on the cooperation of the, male partner. This is not a reliable method and may fail if semen escapes before, ejaculation or is left on external sex organs. Man needs good self-control, both, emotionally and physically, for this method to succeed., , iii., , Lactational amenorrhea (absence of menstruation) Nursing women secrete, hormones that prevent conception for about 6 months. It prevails if there is no menses, and full breast-feeding day and night is maintained. This is more a myth as, breastfeeding is irregular, and 60% women start menstruating by the third month. Not, reliable in instances where baby sleeps through the night, or in case of sore, cracked, or inverted nipples and breast abscess. Many unsuspecting women conceive during, this period before return of menstruation., , ***During this method, no contraceptive devices or chemicals are required. But the failure rate is high., , c. Intra-Uterine Contraceptive Devices or IUCD: The IUCD is a small device usually made, of polyethylene or other polymers. It is inserted into the uterus by a doctor., There are two types of IUCD – the medicated and the non-medicated., , The medicated IUD release either metal ions (copper) or hormones (progesterone), gradually into the female’s body., , 80, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 81 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , Copper T 200 containing a copper wire, progestasert containing progesterone is some, examples of IUCD. The mode of action is not clear, probably it produces non-specific, biochemical and histological changes in the endometrium and the ionised copper has, spermolytic and gametotoxic effects., , These changes impair the viability of the gamete and reduce the chances of fertilisation rather, than its implantation. The copper ions may affect sperm motility, capacitation and, survival., , The hormone releasing devices increase the viscosity of the cervical mucous and thereby, prevent the sperm from entering the cervix. The high levels of progesterone and relatively, low levels of oestrogen make it unfavourable for implantation. The IUCD should be, changed every three years., The advantages of IUCD are – simplicity in insertion; insertion takes only a few minutes;, inexpensive; virtually free of metabolic side effects associated with hormonal pills; and, reversibility to fertility is immediate soon after removal., , The disadvantages are heavy and irregular menstruation and pelvic inflammatory, diseases. Pelvic inflammatory disease (PID) is a collective term that includes acute and, chronic conditions of the ovaries, ducts, uterus and it occurs as a result of infection. Women, with PID suffer from vagina, discharge,, tenderness,, , pelvic, , pain,, , abnormal, , bleeding, chills and fever., Some women suffer uterine, perforations, , leading, , to, , inflammatory response in the, abdomen., 81, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 82 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , d. Oral Contraceptive Pills, , The combined pill consists of two, hormones:, , Oestrogen, , and, , progesterone. This is to be taken every, day orally by the woman. The pill works, by preventing the release of the egg,, thickening of cervical mucus and by altering tubal motility. It is to be prescribed after a, medical check-up. Almost 100% effective if taken regularly. It is an easy and convenient,, woman-controlled method and does not interfere with love-making. There is regular monthly, cycle often with reduced pain and bleeding. Can be discontinued when pregnancy is desired., The pills must be taken regularly and do not work when consumed later than 12 h. The pills, are unsuitable for women over 35 years or those with family history of heart, liver diseases,, hypertension, diabetes or unexplained vaginal bleeding. Failure rates are higher in younger,, less educated women. Adolescents are less likely to take pills correctly and consistently., , e. Emergency Contraceptive Pill, Here, two doses of the pill, separated by 12 h, are taken, within 3 days (72 h) of unprotected intercourse. Depending, on the time of menstruation it is taken, it can prevent, ovulation, fertilization or implantation of the fertilized egg., It is available without prescription. Its uses includeprevention of pregnancy after condom tear/slips, when two, oral pills are missed in succession, when an intra-uterine, device is expelled and there is fear of conception, in case, injectable are delayed by more than 2 weeks., , 82, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 83 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , B. Terminal or Permanent Methods: Permanent surgical contraception is a surgical method, where by the reproductive function of an individual male or female is permanently destroyed., Surgical method is also known as sterilisation. The surgery done on males is vasectomy and on, females is tubectomy., , a. Male Sterilisation: Sterilisation in males is done by vasectomy. It is a permanent, sterilisation done in males where a segment of vas deferens of both the sides is cut and the, cut ends are ligated (joined). The technique is simple and can be performed even in primary, health centres by trained doctors under local anaesthesia. The failure rate is minimal and it, is a very reliable method of contraception but it is an irreversible operation. So it is very, important to get the consent of the person undergoing vasectomy., , 83, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 84 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , b. Female Sterilisation: Occlusion (blocking) of the fallopian tubes is the underlying principle, to achieve female sterilisation. This is known as tubectomy. Female sterilisation can be done, by two procedures — laparoscopy and minilaparotomy. The technique of female sterilisation, through abdominal approach with a special instrument called laproscope is known as, laparoscopy., , The mini-laparotomy is a modification of abdominal tubectomy and requires a small incision, in the abdomen and is conducted under local anaesthesia. It is a suitable procedure at the, primary health centre and very safe, effective and easy also., , 84, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 85 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , B. ASSISTED REPRODUCTIVE TECHNOLOGY:, IN-VITRO FERTILIZATION:, , 1. In vitro fertilisation or IVF is a technique in which egg cells are fertilised by sperms outside, the woman’s body., 2. After fertilisation, the zygote is transferred to the patient. The transfer of the zygote is called, ‘Embryo transfer’., 3. The foetus is then allowed to grow in the uterus. The term ‘test tube babies’ are given to zygotes, formed thus and grown., 4. In vitro fertilisation is usually performed in shallow containers called petri-dishes made of, plastic resin or glass., 5. This technique is used as a treatment for infertility when the normal methods of conception, have failed., 6. It is included under a category known as assisted reproductive technology or ART., 7. Embryos can also be formed by in vivo fertilisation i.e., fusion of sperm within the female. These, embryos can also be transferred into the body of females who cannot conceive., 8. The first test tube baby, Louise Brown was born in England on July 25, 1978. Subash, Mukhopadhyay was the first physician in India to perform IVF and the test tube baby, Durga, was born on July 25, 1978. But it was only after 1981 the technique became popular all over the, world., , PROCEDURE OF IVF:, , 1. In IVF, healthy ova, sperm that can fertilise, and a uterus that can maintain pregnancy are, required., 2. The woman, from whom the ova are collected, is administered fertility medicines to stimulate, multiple follicle development., 85, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 86 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 3. After follicular maturation is achieved, human chorionic gonadotropins or (β-hCG) is, injected, which acts as an analogue of the luteinizing hormone (LH)., 4. This hormone stimulates ovulation, 36 hours after the injection., 5. The egg is retrieved using a transvaginal technique involving an ultrasound guided needle that, pierces the vaginal wall to reach the uterus., 6. From the follicular fluid collected, the ova are identified. The procedure is done in a woman, under general anaesthesia., 7. In the laboratory, the identified eggs are stripped of surrounding cells and prepared for, fertilisation., 8. In the meantime, semen is collected from a donor. The sperm and the egg are incubated, together in a culture media for about 18 hours. (In a more refined technique a single sperm is, injected directly into the egg using the intra cytoplasmic sperm injection or ICSI.), 9. The fertilised egg is passed into special growth medium and maintained until the fertilised egg, has achieved 6-8 celled stage., 10. The embryos are transferred to the patient’s uterus through a thin, plastic catheter that enters, the vagina. Often, several embryos are passed into the uterus to improve chances of implantation, and pregnancy., 11. The patient confirms pregnancy after two weeks. She is administered progesterone, to keep the, uterus lining thickened and suitable for implantation., 12. But the major complication of IVF is the risk of multiple births. This is because of the practice, of transferring multiple embryos., 13. The multiple embryos generated, may be frozen. These embryos are placed in liquid nitrogen, and can be preserved for a long time. The advantage is that patients who fail to conceive may, become pregnant using such embryos without having to go through a full IVF cycle. Alternately,, they could use them for another pregnancy., , 86, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 87 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , TEST TUBE BABIES:, , The term “test tube baby” was first used in 1978 with the successful birth of Louise Joy Brown in, England, using In-Vitro Fertilisation (IVF) by Sir. Robert Edwards and Dr. Patrick Steptoe., Soon after in 1983, Samuel Lee of Singapore became Asia’s first test tube baby, through efforts of, Prof. S.S. Ratnam and Prof. Ng Soon Chye and his team., The term “test tube baby” means a child that is conceived outside a woman’s body. A more, complete definition specifies test tube babies as being conceived in a laboratory through the, scientific process of In-Vitro Fertilisation (IVF)., , 87, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 88 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , STEP BY STEP PROCESS INVOLVED IN TEST TUBE BABY:, STEP 1:, EGG PRODUCTION STIMULATED BY HORMONE THERAPY, Prior to egg retrieval, the woman is prescribed injectable hormones of GnRH and gonadotrophins to, promote the synchronous growth and maturation of the follicles inside her ovaries. Final maturation, of the eggs is accomplished through the injection of hCG 36 hours before egg collection., STEP 2:, EGGS RETRIEVED FROM OVARY, The woman is given a mild sedative or anaesthetic and using an ultrasound vaginal probe with a fine, hollow needle attached to it, the fertility specialist aspirates eggs from the woman’s ovaries. These, samples are promptly brought to the laboratory., STEP 3:, SPERM SAMPLE PROVIDED, On the same day as the egg retrieval, the man is required to produce a fresh semen sample., STEP 4:, EGGS AND SPERM COMBINED TO ALLOW FERTILISATION, The sperm and eggs are mixed together in a Petri dish and then place inside an incubator for a few, days. During this period, the fertility specialist checks for signs of fertilisation and monitors the growth, of the embryos., STEP 5:, FERTILIZED EGGS INTRODUCED INTO THE UTERUS, On the day of embryo transfer, two or three embryos are transferred into the uterus of the woman with, the use of a fine catheter. To strengthen and support the uterine lining and increase the possibility of, implantation, she is advised to administer progesterone or HCG daily., , 88, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 89 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , ARTIFICIAL INSEMINATION:, , Artificial insemination is a fertility treatment method used to deliver sperm directly to the cervix or, uterus in the hopes of getting pregnant., , Two chief approaches to artificial insemination exist: intrauterine insemination (IUI) and, intracervical insemination (ICI)., , Artificial insemination can be a beneficial and successful treatment for some couples who have trouble, conceiving. Some of the conditions a doctor may recommend artificial insemination for include:, , 89, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 90 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 1. Sometimes a man’s sperm isn’t mobile enough to make this trip in the female reproductive, tract., 2. Other times, a woman’s cervix may not be favourable to allow sperm to travel into the, uterus., 3. Couples where a man may have a genetic defect and using donor sperm is preferred, 4. Men with a low sperm count, 5. Men with low sperm motility, 6. Women whose cervical mucus may be unfavourable to getting pregnant, 7. Women with a history of endometriosis, , 90, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 91 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , INTRACERVICAL INSEMINATION (ICI):, , ICI is a type of artificial insemination that involves inserting sperm into the cervix. This is the, passageway just outside the uterus., , The steps for this process include:, , 1., , A woman will monitor her ovulation cycle using a calendar method, ultrasound, by taking, her temperature regularly, or a combination of these. Sometimes, a doctor may prescribe, medications to induce ovulation and increase the likelihood a woman will release multiple eggs., , 2., , A woman’s partner will donate sperm for use or a woman will obtain a sperm sample from a, donor., , 3., , A doctor will insert sperm into the vagina using a special syringe. Another option is to place, the sperm in a cervical cap that’s inserted into the cervix and stays for a designated amount of, time., , 4., , A woman will typically be instructed to lie down for 15 to 30 minutes. This ideally allows the, sperm to move up from the cervix into the uterus., , 5., , A woman can return to her regular activities after this time. In about two weeks or slightly longer,, she’ll take a pregnancy test to determine if the insemination process was successful., , INTRAUTERINE INSEMINATION (IUI):, , IUI is a procedure that involves inserting sperm past the cervix and directly into the uterus. The, steps for this process are similar to that of ICI, but are usually performed at a doctor’s office and with, specially prepared sperm., 91, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 92 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , Additional steps include:, , 1., , The semen is prepared or “washed” to remove potential proteins that could affect fertilization., This also makes the sperm more concentrated. Ideally, this will increase the likelihood a woman, will conceive., , 2., , A doctor will use a special instrument called a speculum to make the uterus easier to access., They’ll use a special, thin instrument inserted through the vagina and place the sperm into the, uterus., , GAMAET INTRA FALLOFIAN TRANSFER (GIFT):, , GIFT is a clinical procedure under assisted reproductive technology. In this process, eggs collected, from a woman’s ovary have mixed with sperm obtained from a male partner in a clinical laboratory, and immediately placed into the fallopian tube of the intended mother for fertilization is termed as, Gamete Intra-Fallopian Transfer., , In the following conditions, GIFT may recommend by the doctors:, , , , Couples have unexplained infertility., , , , Failure of IVF cycle., , , , Religious restriction or ethical issue does not support to perform IVF., , , , Women with at least a single healthy fallopian tube., , , , Male infertility due to poor quality or insufficient sperm count., , 92, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 93 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , GIFT is conducted by the following steps:, , 1. An X-ray is conducted to the patient for determining the presence of at least one healthy, , fallopian tube., 2. After getting all the positive results, the utilization of laparoscopy for the egg retrieval process, , from the ovaries is conducted., 3. Subsequently, sperm is also collected on the same egg retrieval., 4. Freshly collected egg and sperm are then mixed in a catheter., 5. Immediately the mixture of egg and sperm is inserted into the fallopian tube through the, , catheter., 6. Then, the doctor prescribed medication to the intended mother for the uterine lining build-up,, , which is essential for providing support to the fertilization process., 7. In case any collected eggs remain, then it can be saved for future use through the, , cryopreservation process. Similarly, viable excess embryos can also be cryopreserved for, future use through the IVF process., , 93, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 94 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , ZYGOTE INTRA FALLOFIAN TRNASFER (ZIFT):, , ZIFT is also called tubal embryo transfer. ZIFT technique differs from gamete Intrafallopian transfer, (GIFT) in that fertilization takes place in the lab rather than the fallopian tube, but is similar in that the, fertilized egg is transferred to the tube rather than the uterus., , With ZIFT procedure, fertilization occurs in the laboratory. Then the very young embryo is, transferred to the fallopian tube instead of the uterus., , ZIFT PROCEDURE:, , The basic steps in an IVF treatment cycle are ovarian stimulation, egg retrieval, fertilization,, embryo culture, and embryo transfer., 1. OVARIAN STIMULATION: During ovarian stimulation, also known as ovulation, induction, medications or “fertility drugs” are used to stimulate multiple eggs to grow in, the ovaries rather than the single egg that normally develops each month. Multiple eggs are, stimulated because some eggs will not fertilize or develop normally after fertilization., , 2. EGG RETRIEVAL: Egg retrieval is usually accomplished by transvaginal ultrasound, aspiration, a minor surgical procedure that can be performed in the physician’s office or an, outpatient centre. The eggs are aspirated (removed) from the follicles through the needle, connected to a suction device. Removal of multiple eggs can usually be completed in less, than 30 minutes., , 3. FERTILIZATION AND EMBRYO CULTURE: After the eggs are retrieved, they are, examined in the laboratory for maturity and quality. Mature eggs are placed in an IVF, culture medium and transferred to an incubator to await fertilization by the sperm., , 94, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 95 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 4. EMBRYO TRANSFER: The next step in the IVF process is the embryo transfer. The, physician identifies the cervix using a vaginal speculum. One or more embryos suspended, in a drop of culture medium are drawn into a transfer catheter (a long, thin sterile tube), with a syringe on one end. The physician gently guides the tip of the transfer catheter, through the cervix and places the fluid containing the embryos either into the uterine cavity, or into the fallopian tube in the case of ZIFT or GIFT., , 95, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 96 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , SPERM BANKS:, , A sperm bank, semen bank or cryobank is a facility or enterprise which purchases, stores and sells, human semen.,  The semen is produced and sold by men who are known as sperm donors. Sperm sold by a, sperm donor is known as donor sperm.,  The sperm is purchased by or for women for the purpose of achieving a pregnancy or pregnancies, other than by a sexual partner, known as recipient women.,  Sperm is introduced into the recipient woman by means of artificial insemination or by IVF, and the process may also involve donated eggs or the use of a surrogate.,  Sperm banks provide the opportunity to have a baby to single women and coupled lesbians and, to heterosexual couples where the male is infertile., , Recruitment: The finding of a potential sperm donor and motivating him to actually donate sperm is, typically called recruitment.,  A donor must be a fit healthy male,  Normally between 18 and 45 years of age,  Who is willing to undergo frequent and rigorous testing?,  Who is willing to donate his sperm so that it can be used to impregnate women who are, unrelated to and unknown by him,  The donor must agree to relinquish all legal rights to all children which result from his donations,  The donor must produce his sperm at the sperm bank thus enabling the identity of the donor,, and also enabling fresh samples of sperm to be produced for immediate processing., , 96, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 97 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , SCREENING OF DONORS:, A sperm donor must generally meet specific requirements regarding age and medical history.,  Sperm banks typically screen potential donors for a range of diseases and disorders, including, genetic diseases, chromosomal abnormalities and sexually transmitted infections that may, be transmitted through sperm.,  The screening procedure generally also includes a quarantine period, in which the samples, are frozen and stored for at least 6 months after which the donor will be re-tested for the STIs., This is to ensure no new infections have been acquired or have developed during the period of, donation.,  Providing the result is negative, the sperm samples can be released from quarantine and used in, treatments.,  The sperm will be checked to ensure its fecundity and also to ensure that motile sperm will, survive the freezing process.,  If a man is accepted onto the sperm bank's program as a sperm donor, his sperm will be, constantly monitored, the donor will be regularly checked for infectious diseases, and samples, of his blood will be taken at regular intervals.,  All sperm is frozen in vials and stored for as long as the sperm donor may and can maintain it.,  A sperm donor may also be required to produce his medical records and those of his family, often, for several generations.,  Some sperm banks may disallow sexually active gay men from donating sperm due to the, population's increased risk of HIV and hepatitis B.,  Modern sperm banks have also been known to screen out potential donors based on genetic, conditions and family medical history., , 97, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 98 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , COLLECTION:,  A sperm donor will usually be required to enter into a contract with a sperm bank to supply, his semen, typically for a period of six to twenty-four months depending on the number of, pregnancies which the sperm bank intends to produce from the donor.,  In the United Kingdom, for example, where a donor is not permitted to father more than ten, families.,  A sperm donor generally produces and collects sperm at a sperm bank or clinic by, masturbation in a private room or cabin, known as a 'men's production room', 'donor cabin', or a masturbatorium.,  Many of these facilities contain pornography such as videos/DVD, magazines, and/or, photographs which may assist the donor in becoming aroused in order to facilitate production of, the ejaculate, also known as the "semen sample".,  One sample can produce 1–20 vials or straws, depending on the quantity of the ejaculate., , STORAGE:,  The sperm is stored in small vials or straws holding between 0.4 and 1.0 ml of sperm and, cryogenically preserved in liquid nitrogen tanks.,  Following the necessary quarantine period, which is usually 6 months, a sample will be thawed, and used to artificially inseminate a woman or used for another assisted Choosing donors, , REGULATION:,  In countries where sperm banks are allowed to operate, the sperm donor will not usually become, the legal father of the children produced from the sperm he donates, but he will be the, 'biological father' of such children.,  In cases of surrogacy involving embryo donation, a form of 'gestational surrogacy', the, 'commissioning mother' or the 'commissioning parents' will not be biologically related to the, child and may need to go through an adoption procedure., , *******, 98, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 99 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , UNIT – VI, HISTOLOGY, Histology is the study of the structure of biological material and the ways in which individual, components are structurally and functionally related., , It is centre to biological and medical science since it stands at the crossroads between biochemistry,, molecular biology and physiology on the one side, and disease processes and their effects on the other., , PRIMARY TISSUES:, , (Only epithelial and connective tissues are discussed as prescribed in the syllabus), , The term tissue is used to describe a group of cells that are similar in structure and perform a, specific function., Tissues are organized into four broad categories based on structural and functional, similarities. These categories are epithelial, connective, muscle, and nervous., The primary tissue types work together to contribute to the overall health and maintenance of the, human body. Thus, any disruption in the structure of a tissue can lead to injury or disease., , 99, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 100 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , EPITHELIAL TISSUE:, The outer surface of the body and the luminal surfaces of cavities within the body are lined by one, or more layers of cells that completely cover them. Such layers of cells are called epithelia (Sing., Epithelium)., , Epithelial tissue primarily appears as large sheets of cells covering all surfaces of the body exposed to, the external environment and lining internal body cavities. In addition, epithelial tissue is responsible, for forming a majority of glandular tissue found in the human body., Epithelial tissue is derived from all three major embryonic layers. The epithelial tissue composing, cutaneous membranes develops from the ectoderm. Epithelial tissue composing a majority of the, mucous membranes originate in the endoderm. Epithelial tissue that lines vessels and open spaces, within the body are derived from mesoderm., CLASSIFICATION OF EPITHELIAL TISSUES:, Epithelial tissues are classified according to the shape of the cells and by the number of cell layers, present in the tissue., Cell shapes are classified as being either squamous (flattened and thin), cuboidal (boxy, as wide as it, is tall), or columnar (rectangular, taller than it is wide)., Similarly, cells in the tissue can be arranged in a single layer, which is called simple epithelium, or, more than one layer, which is called stratified epithelium., Pseudostratified describes an epithelial tissue with a single layer of irregularly shaped cells that give, the appearance of more than one layer. Transitional describes a form of specialized stratified, epithelium in which the shape of the cells, and the number of layers present, can vary depending on the, degree of stretch within a tissue., 100, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 101 :
ZOOLOGY – DSE 1A, , I., , ENDOCRINOLOGY AND REPRODUCTON, , SIMPLE EPITHELIUM:, , Epithelial tissue is specialized to protect, absorb, and secrete substances, as well as, detect sensations., , It covers every exposed body surface, forms a barrier to the outside world, and controls, absorption., , Epithelium forms most of the surface of the skin, and the lining of the intestinal,, respiratory, and urogenital tracts. Epithelium also lines internal cavities and pass ways, such as chest, brain, eye, inner surface of blood vessels, the heart, and the inner ear., , 101, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 102 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 1. Simple squamous epithelium:, The cells in a simple squamous epithelium have the appearance of thin scales. The, nuclei of squamous cells tend to appear flat, horizontal, and elliptical, mirroring the, form of the cell. Simple squamous epithelium, because of the thinness of the cells, is, present where rapid passage of chemical compounds is necessary such as the lining of, capillaries and the small air sacs of the lung. This epithelial type is also found, composing the mesothelium which secretes serous fluid to lubricate the internal body, cavities., , 2. Simple cuboidal epithelium:, In simple cuboidal epithelium, the nucleus of the box-like cells appears round and is, generally located near the center of the cell. These epithelia are involved in the, secretion and absorptions of molecules requiring active transport. Simple cuboidal, epithelia are observed in the lining of the kidney tubules and in the ducts of glands., , 3. Simple columnar epithelium:, In simple columnar epithelium, the nucleus of the tall column-like cells tends to be, elongated and located in the basal end of the cells. Like the cuboidal epithelia, this, epithelium is active in the absorption and secretion of molecules using active transport., Simple columnar epithelium forms a majority of the digestive tract and some parts of, the female reproductive tract. Ciliated columnar epithelium is composed of simple, columnar epithelial cells with cilia on their apical surfaces. These epithelial cells are, found in the lining of the fallopian tubes where the assist in the passage of the egg, and, parts of the respiratory system, where the beating of the cilia helps remove particulate, matter., , 102, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 103 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 4. Pseudostratified columnar epithelium:, Pseudostratified columnar epithelium is a type of epithelium that appears to be, stratified but instead consists of a single layer of irregularly shaped and differently, sized columnar cells. In pseudostratified epithelium, nuclei of neighbouring cells appear, at different levels rather than clustered in the basal end. The arrangement gives the, appearance of stratification, but in fact, all the cells are in contact with the basal lamina,, although some do not reach the apical surface. Pseudostratified columnar epithelium is, found in the respiratory tract, where some of these cells have cilia., II., , STRATIFIED EPITHELIUM:, A stratified epithelium consists of multiple stacked layers of cells. This epithelium protects, against physical and chemical damage. The stratified epithelium is named by the shape of, the most apical layer of cells, closest to the free space., Stratified squamous epithelium:, it is the most common type of stratified epithelium in the human body. The apical cells, appear squamous, whereas the basal layer contains either columnar or cuboidal cells., The top layer may be covered with dead cells containing keratin., Stratified squamous epithelium can be divided into two types: non-keratinized and, keratinized., In situations where the surface of the epithelium remains moist, the most superficial, cells are living and nuclei can be seen in them. This kind of epithelium is described as, non-keratinized squamous epithelium., , 103, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 104 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , In contrast, at places where the epithelial surface is dry, the most superficial cells die, and lose their nuclei. These cells contain a substance called keratin, which forms a nonliving covering over the epithelium. This kind of epithelium constitutes keratinized, stratified squamous epithelium., The skin is an example of a keratinized stratified squamous epithelium. Alternatively,, the lining of the oral cavity is an example of an unkeratinized stratified squamous, epithelium., Stratified cuboidal epithelium and Stratified columnar epithelium are rare, epithelial seen in the ducts of some glands., CONNECTIVE TISSUES:, The term connective tissue is applied to a tissue which fills the interstices between more specialized, elements; and serves to hold them together and support them. For the latter reason some, authorities prefer to call it support tissue., , 104, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 105 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , LOOSE CONNECTIVE TISSUE:, , 1. Areolar Tissue:, , This tissue is most widely distributed connective tissue in the animal body., , It is named so because it takes the form of fine threads crossing each other in every direction, leaving small spaces called areolae., , The areolar tissue consists of ground substance, the matrix, white, yellow and reticular fibres, and cells like fibroblasts, mast cells, macrophages, lymphocytes, plasma cells, mesenchyme, cells, chromatophores., , AREOLAR TISSUE, , 2. Adipose Tissue:, , It is a fat storing connective tissue. The adipose tissue consists of several spherical or oval, adipose cells. Each adipose cell contains fat globules, due to which the nucleus and the, cytoplasm are displaced to the periphery., , 105, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 106 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , The adipose tissues are found in the subcutaneous tissue, around the heart, kidneys, eyeballs,, mesenteries and omenta, where fat is stored. Adipose tissue is also found in the blubber of, whales and elephants, hump of camel, fat bodies of frog and yellow bone marrow., , ADIPOSE TISSUE, , DENSE CONNECTIVE TISSUE:, It is of two types: dense regular connective tissue and dense irregular connective tissue., , 1. Dense Regular Connective Tissue: In the dense regular connective tissue, the collagen fibres, are present in rows between many parallel bundles of fibres. It is also of two types: white, fibrous connective tissue and yellow elastic connective tissue., , a. White Fibrous Connective Tissue: It consists of mainly white (collagen) fibres which are, arranged in bundles. The fibroblasts are present in rows between the bundles., , White Fibrous Cords (Tendons): The white fibrous connective tissue forms cords, called tendons which connect the skeletal muscles with the bones., , White Fibrous Sheets: White fibrous connective tissue also forms flat plates or sheets., It occurs in the dermis of the skin, connective tissue sheaths of muscles and nerves, and tunica adventitia (= outer coat) of large blood vessel, periosteum of the bone,, perichondrium of the cartilage, pericardium of the heart, diameter of the brain and, spinal cord, renal capsule of the kidney, sclera and cornea of the eye ball and fibrous, capsules of penis and testes and between skull bones., , 106, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 107 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , DENSE REGULAR CONNECTIVE TISSUE, b. Yellow Elastic Connective Tissue: This tissue is mainly made up of much thicker, branched loose network of yellow fibres. The white fibres also occur but they are very fine., The fibroblasts are irregularly scattered. It also contains mast cells, macrophages and, often some adipose cells., Yellow Fibrous Cords (Ligaments): The yellow elastic connective tissue forms cords, called ligaments which join bones to bones., Yellow Fibrous Sheets: The sheets formed by this tissue occur in the walls of blood, vessels, lungs, bronchioles, true vocal cords, cartilage of larynx, trachea, capsules of, spleen and ligament flava which connect adjacent vertebrate., , 2., , Dense Irregular Connective Tissue: It has fibroblasts and many fibres (mostly collagen) that, are oriented differently. This tissue is present in the skin., , DENSE IRREGULAR CONNECTIVE TISSUE, , 107, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 108 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 3. Specialised Connective Tissues: These are of the following types:, a. Skeletal Tissues: These connective tissues form the endoskeleton of the vertebrates. Hard, parts of the body constitute skeleton. These support the body, protect the various organs and, help in locomotion. Skeletal tissues include cartilage and bone., , Cartilage (= Gristle): Cartilage is a soft skeletal tissue. It is not rigid like bone. It is found, more abundantly in vertebrate embryos because most of the bones forming skeleton of the, adult are cartilaginous in the early stage. However, it is commonly found in the body of adult, vertebrates., , Bone: Bone is the hardest tissue in the body and supports various organs. The matrix is, tough containing both inorganic and organic substances. The inorganic salts present in the, matrix are calcium phosphate, calcium carbonate, calcium fluoride, magnesium phosphate,, etc., , b. Vascular Tissues (= Fluid Tissues): Vascular tissues are motile connective tissues, consisting of fluid matrix and free cells. The matrix is without fibres. The matrix is not, secreted by the cells present in it. Vascular tissues transport the materials from one place to, the other., The vascular tissues are of two types: blood and lymph., Blood: Blood is a mobile connective tissue composed of a fluid, the plasma and the cells,, the blood corpuscles. Blood is basis of life. Blood is the softest tissues in the body., Fluids outside the cells are generally called extracellular fluids (ECF). Blood forms about, 30-35 percent of the ECF. The volume of blood in an adult person of 70 kg weight is about, 5.5 litres. It is a slightly alkaline fluid having pH 7.4. pH of blood in arteries is more than in, veins., Plasma: It is slightly alkaline non-living intercellular substance which constitutes about, 55% part of the blood. It is a pale yellow but transparent and clear fluid., , 108, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 109 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , Formed Elements (Blood Corpuscles): Formed elements or blood corpuscles are of the, following three types: Erythrocytes, Leucocytes and Thrombocytes., , Lymph: Lymph is a mobile connective tissue comprising lymph plasma (fluid) and lymph, corpuscles (cells)., Lymph Plasma: It is similar to that of blood but has fewer blood proteins, less calcium, and phosphorus and high glucose concentration. Mainly globulin proteins are present, which are actually antibodies. Other components of the lymph plasma are very much like, that of blood plasma, i.e., organic, inorganic substances, water, etc., Lymph Corpuscles: These are floating amoeboid cells, the leucocytes (white blood, corpuscles), which are mostly lymphocytes. Erythrocytes (red blood corpuscles) and, platelets are absent in lymph., , c. Reticular Connective Tissue: This tissue consists of star-shaped reticular cells whose, protoplasmic processes join to form a cellular network. The reticular fibres are present, on the reticular cells. They are composed of a protein called reticulin. Matrix and some other, cells such as macrophages, lymphocytes and adipose cells are also present., Reticular connective tissue is present in the liver, spleen, lymph nodes, thymus, tonsils,, bone marrow and lamina propria of the gut wall., , RETICULAR CONNECTIVE TISSUE, , 109, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 110 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , d. Pigmented Connective Tissue: The cells are irregular in shape and are called pigment, cells (chromatophores or melanophores) which contain yellowish brown, black or blue, melanin pigment granules. Melanin is in fact, produced by other cells called melanocytes., Chromatophores simply phagocytise the melanin from melanocytes like macrophages., Pigmented connective tissue is present in the choroid, ciliary body and iris of the eye and, dermis of the human skin., , PIGMENTED CONNECTIVE TISSUE, , e. Mucoid Connective Tissue: In addition to above mentioned connective tissues, mucoid, tissue occurs as a foetal or embryonic connective tissue. It is present in the umbilical cord., The most conspicuous component of the mucoid tissue is a jelly like substance, called, Whartson’s jelly., Some delicate collagen fibres and primitive type of fibroblasts arc also present. Mucoid tissue, (mucous connective tissue) also occurs in vitreous humour of the eye and in comb of cock., , 110, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 111 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , HISTOLOGICAL ORGANIZATION OF LIVER:, , T. S. OF LIVER, 1. The liver is the largest gland of the body and remains attached to the posterior concavity of, diaphragm. It consists of five lobes, three are on the left and two on the right sides., , 2. Liver is a spongy, racemose type of structure. It is externally covered by a fibro-elastic serous, coat (liver capsule). Each lobe of liver consists of a number of hepatic lobules separated from, one another by a thin layer of connective tissue called septa or Glisson’s capsule., , 3. Each lobule is polygonal and consists of a mass of polyhedral hepatic cells arranged in radial, rows, called the hepatic cords, around a central or intra-lobular vein. Radial rows of hepatic, cells are 1 or 2 cells thick and anastomosing., , 111, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 112 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 4. Liver cells contain fine granular cytoplasm, large central nuclei and deposits of fat and, glycogen., , 5. Between the hepatic cords are present narrow irregular spaces, the lacunae, through which run, blood capillaries, hepatic sinusoids having broken walls of endothelial cells., , 6. Some specialised Kupffer cells are also found amongst liver cells which generally help in the, destruction of many germs., , 7. At the corners of the adjacent lobules is found the interlobular blood vessels (branch of hepatic, artery and hepatic portal vein), while the intra-lobular blood vessels are lying in the centre of the, lobules. Interlobular blood vessels and bile duct lie within interlobular connective tissue called, the portal areas or canals., , 8. The intercellular spaces are left in between the hepatic cells which receive the secretions of these, cells, the bile. A number of such spaces unite together to form many interlobular bile ductules, ultimately uniting together to form hepatic ducts which open in the common bile duct., , HISTOLOGICAL ORGANIZATION OF STOMACH:, , T. S. OF STOMACH, 112, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 113 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 1. A transverse section of the stomach of Rabbit shows that it consists of four coats:, Serous, Muscular, Sub-mucosa and Mucous coats., 2. The serous coat is the outermost covering of the intestine. It is made up of an outer layer of, squamous epithelium and an inner layer of connective tissue., 3. Muscular coat consists of an outer layer of longitudinal muscle and an inner layer of circular, unstriped muscle fibres., 4. The next inner layer is sub-mucosa, which is a layer of loose areolar connective tissue having, many blood vessels., 5. Outside the mucous coat is a layer called muscularis mucosae, which is a double muscular, layer, having on the outside, longitudinal muscle fibres and in the inner side circular muscle, fibres. Muscularis mucosae are highly developed in the stomach rather than in the intestine., 6. Mucosa coat of the stomach consists of gastric glands closely packed together. The walls of, the gastric glands are glandular, therefore, they produce gastric juice., 7. When the transverse section of the stomach is through cardiac part, the gastric glands are, called cardiac glands. These contain only mucus-secreting cells. In the fundic part as described, by some authors, there are three kinds of cells called mucus-secreting cells, zymogen or pepsin, secreting cells and Oxyntic cells, which produce HCl., , HISTOLOGICAL ORGANIZATION OF INTESTINE:, , 113, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 114 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , T. S. OF INTESTINE, 8. The small intestine is a tube about five meters long. It is divide into three parts; the duodenum, (about 25 cm long), the jejunum (about 2 meters long) and the ileum (about 3 meters long)., 9. The histological structure of the small intestine has four main layers; mucosa, sub mucosa,, muscularis externa and adventitia., 10. The mucosa is highly folded., a) Large circular folds called plicae circulars, most numerous in the upper part of the small, intestine., b) Smaller folds called villi, which are finger like mucosal projections, about 1mm long., c) The lining columnar epithelial cells have fine projections on their apical surfaces, called microvilli., 11. Together, these folds provide a huge surface area for absorption. Between the villi there are, crypts, called crypts of Lieberkuhn, which extend down to the muscularis mucosae. These, crypts are short glands., 12. The lamina propria which underlies the epithelium has a rich vascular and lymphatic, network, which absorbs the digestive products, 13. There is a muscularis mucosae layer immediately at the base of the crypts. The lymphatic, capillaries are called lacteals, and absorb lipids. The vascular capillaries are fenestrated to, aid absorption., , 114, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 115 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 14. The muscularis externa layer contains two layers of smooth muscle, an inner circular and, outer longitudinal, for continuous peristaltic activity of the small intestine., 15. There are around 200 or so lymphoid aggregations called Peyer's patches in the mucosa., 16. The epithelium of the villi is made up of tall columnar absorptive cells called enterocytes,, and goblet cells, which secrete mucin, for lubrication of the intestinal contents, and protection, of the epithelium., , HISTOLOGICAL ORGANIZATION OF PANCREAS (EXOCRINE):, , T. S. PANCREAS, , 115, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 116 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , 17. The pancreas is a gland that is partly exocrine and partly endocrine., 18. The exocrine part of the pancreas contains acinar cells. The acinus is formed of cuboidal, epithelial cells around a narrow lumen. These secrete the pancreatic juice consisting of several, enzymes like trypsinogen, amylase and lipase, which act on proteins, starches and lipids, respectively., 19. The small ducts arising from the acini unite together to form a common pancreatic duct, which, opens at the distal end of duodenum., , 20. The endocrine part of the pancreas is in the form of numerous rounded collections of cells, that are embedded within the exocrine part. These collections of cells are called the pancreatic, islets or the islets of Langerhans., 21. The human pancreas has about one million islets. They are most numerous in the tail of the, pancreas., 22. Individual cells within the islets are smaller and paler than the exocrine cells and assume, spherical or polygonal shapes from moulding by adjacent cells., 23. Of the total number of pancreatic endocrine cells, the proportions of the major cell types are as, follows;, a) The alpha cells (or A-cells) secret the hormone glucagon. They form about 20% of the, islet cells., b) The beta cells (or B-cells) secrete the hormone insulin. About 70% of the cells are of, this type., c) The delta cells (or D-cells) probably produce the hormones gastrin and somatostatin., They are 5-10% of the islet cells., d) The pancreatic polypeptide cells (or PP cells) secrete pancreatic polypeptide. They, are approximately of 1-2%., , 116, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22

Page 117 :
ZOOLOGY – DSE 1A, , ENDOCRINOLOGY AND REPRODUCTON, , HISTOLOGICAL ORGANIZATION OF KIDNEY:, , T. S. KIDNEY (MEDULLA), 1. Kidney tissue consists of an outer part called the cortex, and an inner part called the medulla., 2. The medulla is made up of triangular areas of renal tissues that are called the renal pyramids., 3. Each pyramid has a base directed towards the cortex; and an apex (or papilla) which is directed, towards the renal pelvis, and fits into a minor calyx. Pyramids show striations that pass radially, towards the apex., 4. In the medulla, all the various tubules, ducts and vessels run in the same direction towards, papillary tip., 5. The outer medulla contains a mixture of thick descending and ascending portions of Henle, loops, which are very similar to proximal and distal convoluted tubule., 6. The collecting duct are larger and lined by distinct clear-celled cuboidal epithelium and spindleshaped interstitial cells are numerous., 7. Large collecting ducts are few in number as a result of fusion and open into the calyx at the, papillary tip., *******, 117, , LEO ANTHONY, T. / BGS FIRST GRADE COLLEGE, MYSURU-23 / 2021-22