Questions: ezto.mheducation.com and Physiology 2 with Lab Question 20 - Chapter 19 Quiz October 2024 AV - Con.. Select all that occur during the plateau phase of an acti... Quiz October 2024 AV (i Saved Select all that occur during the plateau phase of an action potential on a cardiac muscle cell. Check All That Apply Calcium is entering the cell. Potassium is exiting the cell. Sodium is entering the cell. Calcium is exiting the cell. Prev 20 of 20 Next MacBook Pro

During the plateau phase of an action potential in a cardiac muscle cell, the following events occur:

1. Calcium is entering the cell.

   • This is correct. During the plateau phase, voltage-gated calcium channels open, allowing calcium ions to enter the cell. This influx of calcium is crucial for the contraction of cardiac muscle cells.

2. Potassium is exiting the cell.

   • This is also correct. Potassium ions continue to exit the cell during the plateau phase, which helps to maintain the membrane potential at a relatively stable level.

3. Sodium is entering the cell.

   • This is incorrect. Sodium ions primarily enter the cell during the initial depolarization phase, not during the plateau phase.

4. Calcium is exiting the cell.

   • This is incorrect. During the plateau phase, calcium ions are entering the cell, not exiting.

In summary, during the plateau phase of an action potential in a cardiac muscle cell, calcium is entering the cell and potassium is exiting the cell.