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Second Semester B.Sc. Psychology- PSY2C01: Human Physiology –Nervous System, , CHAPTER 3, , NON NERVOUS TISSUE AND OTHER MATERIALS, (Neuroglia, Meninges, Cerebro-spinal fluid, Blood-CSF and Blood-Brain Barriers), Non-nervous tissue, Cells associated with central nervous system and the peripheral nervous system, that do not produce electrical impulses. They maintain homeostasis, form myelin, and, provide support and protection for neurons are called non-neuronal tissues., Eg: neuroglia, meninges, Cerebro-spinal fluid, Blood - CSF and blood - brain barriers., Neuroglia, Neuroglia or glial cells are the non-nervous tissue of nervous system. Neuroglia, cells do not conduct nerve impulses. They support, nourish and protect the neurons., They are far more numerous than neurons and are capable of mitosis. Glial cells in the, CNS include, Oligodenrocytes, astrocytes, ependymal cells, and microglia. In PNS,, glial cells include Schwann cells and Satellite cells., Functions, 1. To surround neurons and hold them in place, 2. To supply nutrients and oxygen to neurons, 3. To insulate one neurone from another neurone, 4. To destroy pathogens and remove dead neurons, , Shibu Abdullah, Department of Psychology, Amal College of Advanced Studies, NIlambur, , 1
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Second Semester B.Sc. Psychology- PSY2C01: Human Physiology –Nervous System, , Meninges, The meninges are three membranes that envelop the brain and spinal cord. Brain, and spinal cord are surrounded by three layers of meninges called the outer dura, mater, middle arachnoid mater and inner pia mater. The space between dura mater, and arachnoid mater is known as subdural space. The space between arachnoid mater, and pia mater is known as subarachnoid space. This space is filed with a fluid called, cerebrospinal fluid. Brain and spinal cord are actually suspended in the cerebrospinal, fluid. The primary function of the meninges is to protect the central nervous system., , Cerebro-spinal fluid, Cerebrospinal fluid is a clear and colourless liquid which is seen around the brain, and spinal cord. The fluid is formed from a specialised group of cells, called the choroid, plexus of ventricular ependymal cells which are seen deep inside the brain. The, total volume of cerebrospinal fluid is approximately 150 ml and it is produced at, a rate of 450 ml per day (thus replacing itself three times a day). CSF is seen in the, ventricles (cavities of the brain) of the brain. It is also seen in the space between, meninges., 1. It acts as a cushions or buffer for the brain and spinal cord from injury., 2. It serves as a nutrient delivery and waste removal system for the brain., 3. It provides basic mechanical and immunological protection to the brain inside, the skull., 4. It serves a vital function in the cerebral auto-regulation of cerebral blood flow., Shibu Abdullah, Department of Psychology, Amal College of Advanced Studies, NIlambur, , 2
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Second Semester B.Sc. Psychology- PSY2C01: Human Physiology –Nervous System, , Blood-CSF barrier (BCSFB), Blood-CSF barrier separates the cerebrospinal fluid and blood. The bloodCerebrospinal fluid barrier is a fluid-brain barrier. It is composed of a pair of, membranes. It separates blood from CSF and CSF from brain tissue. The blood-CSF, boundary is a membrane composed of epithelial cells (endothelium) and tight junctions, that link them. The blood CSF boundary is the arachnoid membrane which covers the, surface of the brain. It is more and many plasma proteins thus enter the cerebrospinal, liquid (through pinocytosis or active transport). Their concentrations are lower than, those of blood plasma., Functions, 1. It helps to prevent the passage of most blood-borne substances into the, brain, 2. It facilitates the removal of brain metabolites and metabolic waste into the, blood., 3. It modulates the entry of leukocytes from the blood to the central nerve, cells., , Blood-Brain barrier (BBB), The blood-brain barrier is a highly selective semi permeable barrier that, separates the circulating blood from the brain and extra cellular fluid. It is formed by, the endothelial cells of the capillary wall which are interconnected through tight, junctions, and the basal membrane (basal lamina) of the endothelial cells., Generally, hydrophilic substances do not pass BBB. This system allows the passage of, Shibu Abdullah, Department of Psychology, Amal College of Advanced Studies, NIlambur, , 3
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Second Semester B.Sc. Psychology- PSY2C01: Human Physiology –Nervous System, , some molecules (H2O, O2, CO2, NH3, ethanol) by passive diffusion as well as the, selective transport of molecules such as glucose, water and amino acids and steroid, hormones., Functions, 1. It allows the passage of some molecules by passive diffusion., 2. It permits the selective transport of molecules such as glucose, water and amino, acids., 3. It prevents the passage of antibodies, antibiotics and some drugs., , Shibu Abdullah, Department of Psychology, Amal College of Advanced Studies, NIlambur, , 4
