Initiation of impulse starts in
(B) Axon hillock + initial segment # Neuron:- Neuron generally have four important zones:> 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)> A site where propagated action potential are generated (initial segment in spinal motor neurons, the initial node of Ranvier in cutaneous sensory neurons)> 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# Nissl 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 (E.g.. Methylene blue, thioneine or cresyl violet)> During fatigue or injury of neuron, these bodies fragment and disappear by a process called chromatolysis; within 48 hours of section of the nerve the Nissl substance begins to disintegrate into a fine duct - chromatolysis).
Axon
Axon hillock + initial segmen
Cell body
Dendritic tree
Misc.