Mammals have a double circulation: blood passes through the heart twice in each complete circuit of the body. The right side of the heart pumps blood to the lungs (the pulmonary circulation), and the left side pumps blood to the rest of the body (the systemic circulation).Right side (deoxygenated blood).1. Deoxygenated blood from the body returns to the right atrium through the vena cava.
2. It passes through the tricuspid valve into the right ventricle.
3. The right ventricle pumps it through a semilunar valve into the pulmonary artery, which carries it to the lungs, where it picks up oxygen and loses carbon dioxide.Left side (oxygenated blood).4. Oxygenated blood returns from the lungs to the left atrium in the pulmonary vein.
5. It passes through the bicuspid valve into the left ventricle.
6. The left ventricle pumps it through a semilunar valve into the aorta, which carries it to the rest of the body.The valves only open in one direction. A valve opens when the pressure of the blood behind it is higher than the pressure in front of it, and it closes when the pressure in front becomes higher. This keeps blood moving forwards through the heart.
Having a double circulation means blood can be pumped to the lungs at low pressure, protecting the lung capillaries, and then returned to the heart to be pumped to the body at high pressure. This delivers oxygen to the tissues quickly, which mammals need to support their high metabolic rate.
2. It passes through the tricuspid valve into the right ventricle.
3. The right ventricle pumps it through a semilunar valve into the pulmonary artery, which carries it to the lungs, where it picks up oxygen and loses carbon dioxide.Left side (oxygenated blood).4. Oxygenated blood returns from the lungs to the left atrium in the pulmonary vein.
5. It passes through the bicuspid valve into the left ventricle.
6. The left ventricle pumps it through a semilunar valve into the aorta, which carries it to the rest of the body.The valves only open in one direction. A valve opens when the pressure of the blood behind it is higher than the pressure in front of it, and it closes when the pressure in front becomes higher. This keeps blood moving forwards through the heart.
Having a double circulation means blood can be pumped to the lungs at low pressure, protecting the lung capillaries, and then returned to the heart to be pumped to the body at high pressure. This delivers oxygen to the tissues quickly, which mammals need to support their high metabolic rate.