Axon hillock

Definition

The axon hillock is the specialized region of a neuron where the cell body transitions into the axon. It plays a critical role in initiating and propagating action potentials.

5 Must Know Facts For Your Next Test

1. The axon hillock is located at the junction between the cell body (soma) and the axon.
2. It integrates incoming synaptic signals to determine if an action potential will be generated.
3. Voltage-gated sodium channels are highly concentrated in the axon hillock, facilitating rapid depolarization.
4. The initial segment of the axon, just beyond the hillock, is crucial for action potential initiation.
5. Threshold potential must be reached at the axon hillock for an action potential to propagate down the axon.

Review Questions

• What role does the axon hillock play in a neuron?
• Where is the highest concentration of voltage-gated sodium channels found?
• Why is reaching threshold potential at the axon hillock important?

Related terms

Neuron: A nerve cell that transmits electrical impulses throughout the nervous system.

Action Potential: A rapid rise and fall in membrane potential that propagates along an axon's length.

Voltage-Gated Sodium Channels: Protein channels in neuronal membranes that open in response to changes in membrane potential, allowing sodium ions to enter.