Question

Axon hillock (initial segment)

A) Region where neurotransmitters are released
B) Location of the cell body in a neuron
C) Site where action potentials are initiated
D) Responsible for synaptic transmission

Answer 1

The axon hillock or initial segment is the site where action potentials are initiated due to the high density of voltage-gated Na+ channels. This area is critical for propagating the neuron's electrical signals to other neurons or target cells.

Step-by-step explanation:

The axon hillock, also known as the initial segment, is a specialized part of the neuron where the cell body tapers into the axon. It contains a high density of voltage-gated Na+ channels which are crucial for the initiation of action potentials. When the integrated electrical signals from the dendrites and cell body reach the axon hillock, they can summate to reach a threshold that triggers these voltage-gated Na+ channels to open, initiating an action potential. Therefore, the correct answer to the student's question is:

C) Site where action potentials are initiated.

This location is critical for the neuronal function of transmitting signals across the nervous system. The axon hillock's role is vital in the neuron's ability to communicate with other neurons, muscles, or glands through these action potentials that travel down the axon to the axon terminals. At the axon terminals, neurotransmitters are released to pass the signal to the next cell.