Why does blood not flow through the coronary arteries when heart is contracting?

The coronary arteries supply oxygen-rich blood to the heart muscle. They are located on the surface of the heart and branch out to reach all areas of the heart.

When the heart contracts, the pressure inside the heart chambers increases. This pressure is too high for blood to flow through the coronary arteries. As a result, the coronary arteries are compressed and blood flow to the heart muscle is temporarily stopped.

This lack of blood flow does not damage the heart muscle because the heart is able to store oxygen in its cells. This oxygen is used to fuel the heart muscle during contraction.

When the heart relaxes, the pressure inside the heart chambers decreases and blood flow to the coronary arteries is restored. This allows the heart muscle to receive the oxygen it needs to function properly.

The heart's ability to stop blood flow to the coronary arteries during contraction is an important protective mechanism. It prevents the heart muscle from being damaged by the high pressure inside the heart chambers.