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ANPHY-MIDTERM-REVIEWER-Nervous-System.docx - NERVOUS SYSTEM...

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NERVOUS SYSTEMA group of tissues composed of high specialized cells possessing the characteristics of excitability andconductivity.Peripheral Nervous System1. Cranial Nerves (12 pairs)2. Spinal Nerves (31 Nerves)3. Autonomic Nervous SystemI.FUNCTIONS AND DIVISIONS:A. Somatic EfferentInnervating somatic structures likes skeletalmuscles and skin.B. Visceral EfferentInnervating visceral or involuntary structureslike smooth muscle, cardiac muscles and glands.This is autonomic nervous system.TYPES OF CELLS IN THE NERVOUSSYSTEMThe nervous system is composed of a specialtissues containing two major types of cells.1.Neurons-the active conducting elements2.Neuroglia-the supporting elementsNEURONbasic unit of the nervous system which conductselectrical impulses from one part of the body toanother.consist of a cell body (perikaryon), containing asingle nucleus, and processes transmitting impulse toand from the cell body.TWO TYPES OF PROCESSESA. DENDRITESgroup of short, unsheathed processes arrangedlike branches of a tree that transmit impulsetoward the cell bodyB. AXONSa single, elongated sheathed process conductingimpulses away from the cell body.ACCESSORY CELLSThe non-nervous elements consist of bloodvessels, connective tissue, and supporting cellsknown collective as neuroglia.SYNAPSEPoints of connection between neurons. The axonof one neuron make functional contact withdendrites of another neuron. Certain chemicals,called transmitters are released from axonalendings for impulse to leap the synapticjunction:Main Neurotransmitters:1.Epinenphrine (adrenalin)2. Norepinephrine (noradrenaline)3. Acetylcholineall are releases by autonomic fibers.Acetylcholine released at neuromuscularjunction.NERVE IMPULSECell membrane of unstimulated neurons carries anelectric charge. The inside of the membrane is negativecompared with the outside. A nerve impulse is localizedreversal in the charge of cell and spread there like anelectric current. The sudden electric change in themembrane is called ACTION POTENTIAL. A stimuluscan start this action potential. The electric change is dueto the rapid shift in sodium and potassium across cellmembrane. This occurs very rapidly and followed byrapid return of its membrane to its original state to itsoriginal state so it can be stimulated again.MYELIN SHEATHInsulating material covering axons in central andperipheral nervous systemThe thicker the myelin sheath it is, the faster thepassage of nerve impulse will be.The electric impulse “jumps” from node to nodein myelin sheath instead of travelingcontinuouslyalongthenervefiber.(SALTATORY CONDUCTION OF IMPULSE)I. MORPHOLOGICAL DIVISIONS:A.Central Nervous System1.

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