Which is TRUE about the initial segment of an axon? A) Its membrane potential at threshold is more positive than that of the cell body and dendrites. B) Its membrane potential at threshold is more negative than that of the cell body and dendrites. C) Synapses far from the initial segment are more effective in influencing whether an action potential will be generated in the axon than are synapses close to the initial segment. D) It is the region where neurotransmitter vesicles are docked and ready to be released by exocytosis. E) It can only conduct graded potentials because it lacks voltage-gated Na⁺ channels.

Question

Quizplus · Accepted Answer

The initial segment of an axon has a lower membrane potential at threshold than that of the cell body and dendrites. This is due to a higher concentration of voltage-gated sodium channels in the initial segment. This allows the initial segment to generate an action potential and propagate it down the axon.

Which Is TRUE About the Initial Segment of an Axon