Question

Depolarization of an action potential occurs when

A) When K⁺ floods out of the axon
B) Ca²⁺ floods into the dendrites
C) Na⁺ channels open and Na⁺ floods into the axon
D) The Na⁺/K⁺ pump creates a gradient
E) When negatively charged proteins align with the membrane

Answer 1

Depolarization of an action potential is caused when Na+ ions rush into an axon through voltage-gated sodium channels, leading to a reversal of the membrane charge necessary for nerve impulse conduction.

Step-by-step explanation:

Depolarization of an action potential occurs when the neuron receives a stimulus strong enough to reach a threshold, leading to the opening of voltage-gated Na+ channels. As a result, Na+ floods into the axon, causing the inside of the cell to become more positively charged in relation to the outside, shifting the membrane potential from -70mV towards and above 0mV, often reaching around +30mV to +40mV. This process reverses the charge across the neuron's membrane, a key step in transmitting a nerve impulse along an axon. Repolarization follows as the membrane becomes less permeable to Na+ and voltage-gated K+ channels open, allowing K+ to exit the cell and restore the membrane potential back toward the resting state.

Depolarization of an action potential is caused when Na+ ions rush into an axon through voltage-gated sodium channels, leading to a reversal of the membrane charge necessary for nerve impulse conduction.