question_answer

  Describe double circulation in human beings. Why is it necessary?

Answer:

                  The blood passes through the heart twice through separate pathways for completing one cycle. This type of circulation is called double circluation (i) Systemic circulation (ii) Pulmonary circulation (i) Systemic circulation: It supplies oxygenated blood from left auricle to left ventricle, which is pumped to aorta to distribute blood to various body parts. The deoxygenated blood is collected from the various body organs by the veins to pour into vena cava and finally into the right atrium (auricle). Right atrium transfers this blood into the right ventricle. (ii) Pulmonary circulation: The deoxygenated blood is pushed by the right ventricle into the lungs for oxygenation through pulmonary artery. The oxygenated blood is brought back to left atrium of the human heart through pulmonary vein. From left atrium, the oxygenated blood is pushed into the left ventricle. The left ventricle pumps oxygenated blood into aorta for systemic circulation. These two types of circulation taken together is called double circulation. Necessity of Double Circulation; in humans, having four chambered heart (which consists of two auricle and two ventricle). The left side and right side of heart is completely separated to prevent the oxygenated blood from mixing with deoxygenated blood. Such a separation allows a highly efficient supply of oxygen to the body cells which is necessary for producing a lot of energy. This energy is useful in case of human beings that have high energy need because they constantly require energy to maintain their body temperature.