Patient Care Technician (PCT) AAH Practice Exam

What happens when the cardiac muscle cell is stimulated?

1. It repolarizes

2. It relaxes

3. It depolarizes

4. It contracts

The correct answer is: It depolarizes

When a cardiac muscle cell is stimulated, it undergoes a process known as depolarization. This is the initial phase of the action potential in the cardiac muscle. During depolarization, there is a rapid influx of sodium ions into the cell, which causes the inside of the cell to become more positively charged compared to the outside. This change in charge triggers a cascade of events that ultimately leads to the contraction of the cardiac muscle fiber. The contraction of the cardiac muscle is essential for pumping blood throughout the body. The stimulation that causes depolarization is initiated by electrical impulses from the heart's pacemaker cells, specifically the sinoatrial (SA) node, which ensures the heart beats in a coordinated and rhythmic manner. In summary, depolarization is a crucial step that leads to the contraction of the cardiac muscle, enabling the heart to function effectively as a pump.