ATI Pathophysiology Practice Exam

What occurs at the onset of systole in a healthy heart?

1. The atria contract

2. The ventricles contract

3. The heart rate slows

4. The valves close

The correct answer is: The ventricles contract

At the onset of systole in a healthy heart, the ventricles contract. Systole refers specifically to the phase of the cardiac cycle when the heart muscle contracts, which occurs after the ventricles have filled with blood during diastole. During this contraction, blood is ejected from the ventricles into the pulmonary artery and the aorta, leading to the circulation of blood throughout the body. This process is crucial for maintaining blood flow and ensuring that oxygen-rich blood reaches various tissues and organs. The contraction of the ventricles is initiated by electrical impulses from the sinoatrial node that spread throughout the heart, resulting in synchronized contraction. While other cardiac events occur in relation to systole, such as the closing of valves or changes in heart rate, the key defining feature of systole itself is the contraction of the ventricles.