CVS Practice Test

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Question: 1 / 400

In phase 0 of the non-pacemaker action potential, which ion is responsible for the influx?

Potassium

Calcium

Sodium

In phase 0 of the non-pacemaker action potential, the key event is the rapid depolarization of the cell membrane, which is primarily driven by the influx of sodium ions. When a stimulus reaches a certain threshold, voltage-gated sodium channels open, allowing sodium ions to flow into the cell. This rapid influx of sodium is what causes the membrane potential to become more positive, leading to the initial phase of the action potential.

Understanding the role of sodium in this phase is crucial because it highlights the importance of sodium channels in generating action potentials in non-pacemaker cardiac cells, such as those found in the atria and ventricles of the heart.

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Chloride

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