CHAPTER 12 PART 1

CHAPTER 12 PART 1 - CHAPTER 12 Two major anatomical...

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CHAPTER 12 Two major anatomical subdivisions Central nervous system (CNS) Peripheral nervous system (PNS) nerve = ganglion = Functional divisions 1) Sensory (__________) divisions ___________________ A) visceral sensory division B) somatic sensory division 2) Motor (__________) division _______________________ a) visceral motor division (ANS) effectors : cardiac, smooth muscle, glands aa) sympathetic division (action) bb) parasympathetic division (digestion) b) somatic motor division effectors : skeletal muscle Fundamental neuron types Sensory (afferent) neurons Interneurons (association neurons) Motor (efferent) neuron Fundamental properties of neurons Excitability (irritability) Conductivity Secretion
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Neuron structure Cell body = perikaryon= ________ compartmentalizes RER into Nissl bodies Vast number of short dendrites Singe axon (nerve fiber) arising from axon hillock for rapid conduction Neuron types Multipolar neuron Bipolar neuron Unipolar neuron Anaxonic neuron What is the difference between and neuron and a neuroglial cell? Neuroglial Cells Oligodendrocyte s Astrocytes Ependymal cells Microglia (macrophages) formed from monocytes Schwann cells Satellite cells
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Myelin Sheath _______________in CNS & _____________________ in PNS formed from wrappings of plasma membrane In PNS, hundreds of layers wrap axon the outermost coil is ______________ In CNS , no neurilemma or endoneurium Gaps between myelin segments = ________________ Initial segment (area before 1st schwann cell) & axon hillock form trigger zone where signals begin Speed of Nerve signal Speed of signal transmission along nerve fibers Speeds small, unmyelinated fibers = 0.5 - 2.0 m/sec small, myelinated fibers = 3 - 15.0 m/sec large, myelinated fibers = up to 120 m/sec Functions fast signals supply skeletal muscles & transport sensory signals for vision & balance Regeneration Healthy axon stub puts out several sprouts Tube guides lucky sprout back to its original destination
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Electrical potential and currents Neuron doctrine -- nerve pathway is not a continuous “wire” but a series of separate cells
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CHAPTER 12 PART 1 - CHAPTER 12 Two major anatomical...

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