An action potential in a neuron occurs due to depolarization of the axon which causes voltage gated Na+ to open. Once the cell is depolarized, K+ channels open so that this ion can leave the cell. During this time, the membrane potential decreases below resting levels in a process known as which of the following? hyperpolarization hypopolarization saltatory conduction
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Depolarization occurs when the membrane potential becomes less negative. Then, K+ channels open, allowing potassium ions to leave the cell. This outflow of positive ions causes the membrane potential to become more negative than the resting potential. Show more…
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An action potential is triggered, causing voltage-gated Na+ channels to open. Na+ diffuses into the cell and depolarizes the cell membrane. Voltage-gated Na+ channels inactivate and voltage-gated K+ channels open. K+ exits the cell to repolarize the cell membrane while Na+ diffuses further down the axon, depolarizing the membrane towards the nearest Node of Ranvier. Previously inactivated Na+ channels close completely, but continued K+ diffusion results in hyperpolarization of the membrane and a brief refractory period before returning to resting potential. Na+ channels further down the axon open in order to conduct the action potential. Voltage-gated K+ channels sequentially close, and the resting membrane potential is restored. Voltage-gated calcium channels inactivate, preventing calcium outflow.
Sai S.
When the nerve cell membrane is at its "resting potential," the potential difference across the membrane is about -70 mV. When a nerve impulse travels down the axon of a nerve cell (shown in this figure taken from the OpenStax Biology textbook), the potential difference across the membrane changes to about +30 mV. This change is called depolarization. Then, the potential difference across the membrane returns to its initial resting state in a process called repolarization. In response to a signal, the soma of the nerve cell becomes depolarized. The depolarization spreads down the axon, and the membrane repolarizes as sodium channels close and additional potassium channels open. Once the membrane is repolarized, it cannot depolarize again. The action potential continues to travel down the axon, maintaining its resting state until the next depolarization.
Sri K.
B. The Action Potential Action potentials are changes in the movement of ions across the axon membrane, which usually begin in the resting value of about -70 mV and reach a level called the threshold. During the action potential, sodium channels depolarize the axon, causing the inside of the membrane to become +30 mV. At this point, the sodium channels become inactivated and the flow of sodium ceases. Simultaneously, potassium channels open and positively charged potassium ions rush out of the axon. The movement of potassium out of the axon repolarizes the membrane potential from +30 mV back down to the resting membrane potential of -70 mV. Then the channels close, and movement of potassium ions ceases. In summary, the action potential consists of a rapid depolarization followed by a rapid repolarization.
Adi S.
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