Answer to Question #68123 in Human Anatomy and Physiology for cherylee
The human heart consist of 4 chambers, explain how this design supports metabolism in endothermic animals.
Animals have systemic and pulmonary circuits each serving its own purpose. The pulmonary circuit starts with the venous blood that is oxygen deficit. Then this blood is filled with oxygen in the lungs and it goes back to the heart. The systemic circuit starts with the arterial blood that is oxygen rich. Then this blood goes to all body areas, where the oxygen is transferred to the cells and then goes back to the heart. If the heart has 3 chambers, then the blood from the pulmonary circuit and the blood from the systemic circuit end up in the same ventricle and are mixed up there. In this case, the blood that goes to the systemic circuit still lacks oxygen. If the heart has 4 chambers, then the blood from the pulmonary circuit is separated from the blood from the systemic circuit. Thus, the blood that goes to the systemic circuit is richer with the oxygen. Since the metabolism in endothermic animals is much faster than in ectothermic animals, it requires more oxygen. If the body is fed with mixed blood it could not have enough oxygen to support homeothermy, so the heart should have 4 chambers.