The blood pressure in the large systemic arteries is greatest during:
A.
Ventricular systole.
B.
Atrial diastole.
C.
Ventricular diastole.
D.
Atrial systole.
The Correct answer and Explanation is:
The correct answer is:
A. Ventricular systole.
Explanation:
Blood pressure in the large systemic arteries is highest during ventricular systole. To understand why, it’s essential to review the cardiac cycle and how it affects arterial pressure.
1. Cardiac Cycle Overview: The cardiac cycle consists of two main phases: systole and diastole. Systole is when the heart contracts, and diastole is when the heart relaxes. These phases alternate to ensure that blood is pumped effectively through the body.
2. Ventricular Systole: During ventricular systole, the ventricles of the heart contract forcefully. This contraction increases the pressure within the ventricles significantly. The high pressure in the ventricles is then transmitted to the large arteries (like the aorta) through the semilunar valves (aortic and pulmonary valves). Because the heart pumps blood into the arteries with significant force during this phase, the pressure in the large systemic arteries peaks. This is known as systolic pressure.
3. Arterial Pressure Dynamics: The arterial pressure measured during ventricular systole is termed systolic blood pressure. It is the maximum pressure exerted on the arterial walls when the heart contracts and ejects blood. This pressure is critical for ensuring that blood reaches all the tissues and organs efficiently.
4. Other Phases:
- Atrial Diastole: During atrial diastole, the atria are relaxed and filling with blood, but this phase does not significantly affect the pressure in the systemic arteries. The pressure in the arteries is relatively lower compared to systole.
- Ventricular Diastole: During ventricular diastole, the ventricles are relaxed, and the arterial pressure drops as blood moves away from the heart. This results in a lower arterial pressure known as diastolic pressure.
- Atrial Systole: During atrial systole, the atria contract to push blood into the ventricles. This phase does contribute to the overall filling of the ventricles but does not cause a significant increase in arterial pressure compared to ventricular systole.
In summary, the highest blood pressure in the large systemic arteries occurs during ventricular systole, when the ventricles contract and force blood into the arteries, resulting in peak systolic pressure.