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Physiology

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Nerve Muscle Physiology

Question
14 out of 24
 

Initiation of impulse starts in. (DNB June-2011)



A Axon

B Axon hillock + initial segment

C Cell body

D Dendritic tree

Ans. B Axon hillock + initial segment

a. Neuron: - Neuron generally have four important zones: -

i. There is a Receptor, or Dendritic zone, where multiple local potential changes generated by synaptic connections are integrated (i.e. Non conducted local potentials are integrated in the receptor zone).

ii. A site where propagated action potential are generated (initial segment inspinal motor neurons, the initial node of Ranvier in cutaneous sensory neurons).

iii. An axonal process that transmits propagated impulses to the nerve endings and

iv. The nerve endings, where action potential cause the release of synaptic transmitters.

b. See the given figure below: -

Figure: Functional organization of neurons.

Nissi bodies (granules): —are small basophilic granules, membranous organelles containing ribosomes; present through out the cell body (soma, or perikaryon) except in axon hillock (from where axon arises); flow into the dendrites but not into axon; they are stained with basic dyes (eg. Methylene blue, thionine or cresyl violet); During fatigue or injury of neuron, these bodies fragment and disappear by a process called chromatolysis: Q within 48 hours of section of the nerve the Nissi substance begins to disintegrate into a fine duct —chromatolysis).

Nerve Muscle Physiology Flashcard List

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