Presentation on theme: "THE CENTRAL NERVOUS SYSTEM(CNS)"— Presentation transcript:
1 THE CENTRAL NERVOUS SYSTEM(CNS) بسم الله الرحمن الرحيمTHE CENTRAL NERVOUS SYSTEM(CNS)Dr.Mohammed Sharique Ahmed QuadriAssistant prof. PhysiologyAl Maarefa College
2 ORGANIZATION OF NERVOUS SYSTEM The Nervous system is organized into1. Central Nervous System (CNS)BRAINSPINAL CORD2. Peripheral Nervous SystemNerve fibers that carry information between CNS and other parts of body at periphery.
4 CNS Central nervous system regulates body activities. BRAINSPINAL CORD
5 PERIPHERAL NERVOUS SYSTEM (PNS) Peripheral Nervous System is sub divided intoAfferent Division (Sensory) – which carry information to CNSEfferent Division (Motor) – which carry information from CNS to muscle and glands.
6 PNS [cont] Efferent (Motor) division of PNS is further divide into Somatic Nervous System– it is under our voluntary control E.g. fibers of motor neuron that supply skeletal muscle.Autonomic Nervous System – it is not under our control ( involuntary).
7 PNS [cont] Autonomic Nervous System (ANS) ANS– supplies cardiac muscle, smooth - muscle, glands.ANS is divided intoSympathetic ANSParasympathetic ANSEnteric ANS– in the wall of digestive tract
9 FUNCTIONAL CLASSES OF NEURONS There are THREE functional types of NeuronsAfferent Neurons– which carry information to CNS.Efferent Neurons– which carry information away from CNS (to the periphery).Interneurons– They form interactive net-work between neuron.
15 GLIAL CELLS or NEUROGLIA Glial cells are connective tissue of CNS.Glial cells support the interneurons physically, metabolically, and functionally.They do not conduct nerve impulses.Glial cells are of FOUR types.
16 GLIAL CELLS or NEUROGLIA (cont) There are 4 type of Glial CellsAstrocytesOligodendrocytesMicrogliaEpendymal Cells
18 Important Functions Of Glial Cells 1. AstrocytesFunctionsFormation of blood – brain – barrierFormation of neural scar tissueHelps maintain optimal ion conditions for neural excitability2. OligodendrocytesForms myline sheath around axons in the CNS.
19 Important Functions Of Glial Cells 3. MicrogliaFunctionsPhagocytosis [ defense cells of CNS]Release nerve growth factor.4. Ependymal CellsFormation of Cerebrospinal fluid [CSF].Work as Neural Stem Cell – to form new neurons and glial cells.
21 Protection Of BrainAs CNS is very delicate, it is protected by – skull bone [covers the brain] and Vertebral column [surrounds the spinal cord].Meninges – cover brain and spinal cord.Meninges lie between bony covering [outside] and nervous tissue [inside]. Meninges are Durameter, Arachnoid and Piameter.CSF - Cerebro Spinal Fluid is present in subarachnoid space. CSF works as cushion.Blood - brain barrier(BBB) – it selectively allows the materials to pass to brain.
23 Cerebro Spinal Fluid [CSF] It surrounds brain and spinal cord.It is present in subarachnoid space.It is formed by choroid plexuses [capillaries in the piameter] of ventricles in the brain.Volume of CSF is about 125 – 150 ml.
24 CSF [cont] Clinical Note Hydrocephalus [water in the brain]. Occurs if CSF accumulates more, due to the block in its circulation or reabsorption.If hydrocephalus is untreated, increased CSF pressure can lead to brain damage and mental retardation.Treatment – surgically shunting the excess CSF to veins elsewhere in the body.
25 ‘Important Information’ Brain function depends onOxygenGlucoseBrain needs continuous supply of O2 and Glucose.Brain damage results if- brain gets no O2 supply for 4 to 5minsor- no glucose supply for 10 to 15mins.
26 References Human physiology by Lauralee Sherwood, seventh edition Text book physiology by Guyton &Hall,11th editionText book of physiology by Linda .s contanzo,third edition