Question

As an action potential is initiated, the membrane is ______. This is caused by the ____ of ____ ions.

1) hyperpolarized, efflux, Na⁺
2) depolarized, influx, Na⁺
3) depolarized, influx, K⁺
4) hyperpolarized, influx, Na⁺
5) depolarized, efflux, Na⁺

Answer 1

During the initiation of an action potential, the membrane becomes depolarized due to the influx of Na+ ions.

Step-by-step explanation:

As an action potential is initiated, the membrane is depolarized. This is caused by the influx of Na+ ions. An action potential involves several key steps where sodium and potassium ions move across the neuron's membrane. Initially, a stimulus causes some sodium channels to open, leading to a rush of Na+ ions into the neuron. This rapid influx of sodium ions reduces the negative charge inside the cell and results in depolarization.

If the threshold of excitation is reached, this process leads to a full-blown action potential, which is essentially an electrical signal that travels down the neuron. This depolarization triggers the propagation of the action potential along the membrane. After the peak of the action potential, K+ channels open and K+ ions leave the cell, leading to repolarization of the membrane.