Arterial blood supply to heart muscle is continuous whether the heart is in systole or diastole.
The Correct Answer and Explanation is :
The arterial blood supply to the heart muscle (myocardium) is not continuous during both systole and diastole. Blood flow to the myocardium is primarily supplied by the coronary arteries, which are responsible for delivering oxygen and nutrients necessary for the heart muscle to function. The coronary circulation does, however, show different characteristics during systole and diastole.
Explanation:
- During Diastole (Relaxation Phase):
During diastole, the heart is relaxed, and the ventricles fill with blood. This is the period when the coronary arteries are most effective in supplying blood to the heart muscle. The coronary arteries arise from the base of the aorta, just above the aortic valve, and as the heart muscle relaxes, the aorta recoils and pushes blood into the coronary arteries. This blood flow is continuous during diastole, and because the myocardium is not contracted, the vessels are not compressed, allowing for optimal perfusion of the heart muscle. - During Systole (Contraction Phase):
During systole, when the heart contracts to pump blood out, the coronary arteries, especially those in the myocardium itself, are compressed due to the contraction of the heart muscle. This compression can reduce blood flow to the heart tissue during systole. As a result, the coronary arteries do not receive blood during the contraction phase. However, once systole ends, blood flow returns to the myocardium in diastole, replenishing the oxygen and nutrients needed by the heart muscle. The heart muscle relies on this diastolic perfusion for its oxygen supply. - Coronary Circulation Adaptations:
To compensate for the intermittent blood supply during systole, the coronary vessels are designed to allow rapid blood flow during diastole. The left coronary artery, in particular, has a larger caliber, ensuring greater perfusion during diastole, which is essential for maintaining the heart’s metabolic needs.
In summary, while coronary artery blood flow is intermittent, it is crucial during diastole and minimal during systole due to the physical properties of the heart’s pumping action.
Now, I’ll generate an image to illustrate the difference in coronary blood flow during systole and diastole.
Here is the illustration showing the arterial blood supply to the heart muscle during systole and diastole. It highlights the changes in coronary blood flow, with blood flowing freely during diastole and being compressed during systole. Let me know if you need further clarification!