Axon hillock

Axon Hillock

The axon hillock is a specialized part of a neuron that connects the cell body (or soma) to the axon. It is the last site in the soma where membrane potentials propagated from synaptic inputs are summated before being transmitted to the axon.

Structure

The axon hillock is a cone-shaped area from which the axon arises. It is rich in cytoplasm and free of Nissl bodies, which distinguishes it from the soma. The axon hillock also lacks the dendrites found on the soma, but it contains a high density of voltage-gated sodium channels.

Function

The primary function of the axon hillock is to act as the integrative zone of the neuron. It collects and processes signals from the dendrites and soma, and if the total strength of these signals surpasses a certain threshold, it generates an action potential. This action potential is then propagated along the axon, leading to the release of neurotransmitters at the synaptic cleft.

Clinical significance

Abnormalities in the axon hillock can lead to various neurological disorders. For example, damage to the axon hillock can impair the neuron's ability to generate action potentials, leading to conditions such as epilepsy and multiple sclerosis.

See also

• Neuron
• Action potential
• Neurotransmitter