The heart
- The heart consists of four chambers and four major blood vessels.
- Deoxygenated blood goes to the right side and oxygenated blood into the left side. The two sides of the heart are completely separated by the muscular septum.
- Here’s how the blood flows through the heart:
- Vena cava brings deoxygenated blood from the whole body into the right atrium.
- The right atrium contracts and forces the blood into the right ventricle, through the valves. Valves prevent the back flow of blood.
- When the right ventricle is full of blood the muscles in its wall contract, forcing the blood through more valves through the pulmonary artery. This carries deoxygenated blood to the lungs where it picks up oxygen.
- Oxygenated blood returns from the lungs to the left atrium of the heart in the pulmonary vein. When the left atrium is full it contracts and squeezes blood through valves into the left ventricle.
- The ventricle walls then contract and push the blood up more valves into the aorta. The aorta is a large blood vessel that carries oxygenated blood around the body. The wall of the left ventricle is thicker than the right as it needs more muscle to pump blood around the whole body whereas the right ventricle needs only pump to the lungs.