The axon hillock refers to the triangular, cone-shaped region of a nerve cell body which serves as the origin from which the nerve axon extends. The axon hillock helps to differentiate the axon from a dendrite of a nerve cell on microscopy.
This anatomically and functionally specialized area is devoid of large cytoplasmic organelles such as Nissl granules and Golgi complexes but, however, contains microtubules, neurofilaments, mitochondria, and vesicles, as well as a high concentration of ion channels.
The axon hillock plays an important role in neural communication. It serves as a neuron's primary integrative zone, receiving various excitatory and inhibitory stimuli. It determines whether or not the sum of all incoming signals warrants the propagation of an action potential and transmission of a signal.
The region of the nerve axon which lies between the apex of the axon hillock and the starting point of the myelin sheath is called the initial segment. This segment is the actual site where the action potential is generated. Once generated in the initial segment, the action potential then propagates along the axon.
English: Axon hillock
Latin: Colliculus axonis
|Definition||Pyramidal-shaped region connecting axon to cell body|
|Structure||Lacks large cytoplasmic organelles: Nissl bodies, Golgi cisternae
Contains numerous voltage-gated ion channels
|Function||Integration of incoming synaptic stimuli and generation of an action potential|
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