What occurs during phase 1 of action potential?

What occurs during phase 1 of action potential?

• A. Rapid Na influx
• B. Initial repolarization
• C. Ca influx
• D. Complete depolarization

Answer: (B)

During phase 1 of the action potential, initial repolarization occurs. This phase follows the rapid depolarization that is primarily due to the influx of sodium ions during phase 0. As the membrane potential reaches its peak, sodium channels begin to inactivate. Concurrently, potassium channels open, allowing potassium ions to exit the cell. This outflow of positive charge leads to a decrease in the membrane potential, which characterizes the initial repolarization phase. In this context, understanding the sequence and action of ion channels is crucial, as it explains how the heart’s electrical conduction system functions to propagate impulses and facilitate coordinated contractions. This initial repolarization is a subtle but critical shift in the membrane potential that sets the stage for further phases of the action potential.

During phase 1 of the action potential, initial repolarization occurs. This phase follows the rapid depolarization that is primarily due to the influx of sodium ions during phase 0. As the membrane potential reaches its peak, sodium channels begin to inactivate. Concurrently, potassium channels open, allowing potassium ions to exit the cell. This outflow of positive charge leads to a decrease in the membrane potential, which characterizes the initial repolarization phase.

In this context, understanding the sequence and action of ion channels is crucial, as it explains how the heart’s electrical conduction system functions to propagate impulses and facilitate coordinated contractions. This initial repolarization is a subtle but critical shift in the membrane potential that sets the stage for further phases of the action potential.