Library · Physiology
Coronary circulation
Make it clearer
The heart is the organ that consumes the most oxygen per gram of tissue, and it has its own supply system: the coronary circulation, which takes about 5 percent of all the blood the heart pumps each minute.
The odd part is when that blood arrives. It is not when the heart squeezes, in systole: the peak is in diastole, the moment when the heart relaxes. The reason is that as it contracts, the heart muscle crushes its own vessels from the outside. It is a hose running through a closed fist: while it squeezes, less gets through.
And there is another catch. Even at rest, the heart muscle keeps 60 to 70 percent of the oxygen that blood brings. Since there is little room left to pull out more, when the heart needs more oxygen that extra demand is met mainly by sending it more blood.
In brief
The heart uses more oxygen per unit of mass than any other organ, and its coronary circulation takes about 5 percent of cardiac output.
Its flow is paradoxical: the peak comes in diastole, because in systole the muscle squeezes those vessels from the outside.
A hose running through a closed fist: while it squeezes, less gets through.
At rest, 60 to 70 percent of the oxygen in that blood is already extracted.
That leaves little reserve: extra demand is met mainly by increasing flow.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Coronary Circulation, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated