Biology · Transport in humans. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
The heart is a pump made of muscle. It has four chambers: two atria at the top receive blood from veins, and two ventricles below pump it out into arteries. The septum separates the right side (deoxygenated blood) from the left side (oxygenated blood).
In one heartbeat the atria contract and push blood into the ventricles. Then the ventricles contract. The atrioventricular valves close so blood cannot go back to the atria, and the semilunar valves open to let blood into the arteries. When the ventricles relax, the semilunar valves close.
The heart muscle gets its own oxygen and glucose from the coronary arteries. If they are blocked, the result is coronary heart disease.
In a diagram the heart is drawn as if it faces you, so the left side of the heart is on the right of the page. Also, valves do not pump blood: they only stop it flowing backwards.
Answer: 5250 cm3 per minute (5.25 dm3 per minute).
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