The statement 'Systole and diastole usually refer to the contraction and relaxation of the ventricles' is:

The statement 'Systole and diastole usually refer to the contraction and relaxation of the ventricles' is:

• A. True
• B. False
• C. Systole: contraction of ventricles; diastole: relaxation of atria
• D. They refer to pressure changes in arteries only

Answer: (A)

Systole and diastole describe the phases of the cardiac cycle defined by ventricular activity. Systole is when the ventricles contract and eject blood into the aorta and pulmonary artery, while diastole is when the ventricles relax and fill with blood. The statement is true because these terms are most commonly used to refer to the ventricles’ contraction and relaxation, which drive the arterial pressures we measure as systolic and diastolic pressures. There is a nuance: atrial systole does occur and adds a bit of ventricular filling, but the standard definitions of systole and diastole focus on the ventricles. The option that assigns diastole to atrial relaxation would be misleading, and saying the terms refer only to pressure changes in arteries misses the heart’s role in generating those pressures.

Systole and diastole describe the phases of the cardiac cycle defined by ventricular activity. Systole is when the ventricles contract and eject blood into the aorta and pulmonary artery, while diastole is when the ventricles relax and fill with blood. The statement is true because these terms are most commonly used to refer to the ventricles’ contraction and relaxation, which drive the arterial pressures we measure as systolic and diastolic pressures.

There is a nuance: atrial systole does occur and adds a bit of ventricular filling, but the standard definitions of systole and diastole focus on the ventricles. The option that assigns diastole to atrial relaxation would be misleading, and saying the terms refer only to pressure changes in arteries misses the heart’s role in generating those pressures.