Functioning of the Heart
- Deoxygenated blood coming from the body flows into the right atrium via the vena cava
- Once the right atrium has filled with blood, the heart gives a little beat and the blood is pushed through the atrioventricular valve into the right ventricle
- The walls of the ventricle contract and the blood is pushed into the pulmonary artery through the semilunar valve, which prevents blood from flowing backwards into the heart
- The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place
- This is why there has to be low pressure on this side of the heart – blood is going directly to capillaries which would burst under higher pressure
- Oxygen-rich blood returns to the left atrium via the pulmonary vein
- It passes through the atrioventricular valve into the left ventricle
- The thicker muscle walls of the ventricle contract to push the blood forcefully into the aorta and all the way around the body
- The semilunar valve in the aorta prevents the blood from flowing back down into the heart
