Blood circulation in the human heart is termed "double circulation" because it involves two distinct pathways named pulmonary circulation and systemic circulation. In pulmonary circulation, blood travels from the heart to the lungs and back, allowing for oxygenation. Systemic circulation then carries oxygen-rich blood from the heart to the body's tissues and returns oxygen-depleted blood to the heart. This dual process ensures efficient delivery of oxygen and nutrients to cells while removing waste products.
1. Pulmonary Circulation: In this circuit, deoxygenated blood from the body is pumped by the right ventricle of the heart to the lungs via the pulmonary artery. In the lungs, carbon dioxide is exchanged for oxygen, and oxygenated blood returns to the left atrium of the heart via the pulmonary veins.
2. Systemic Circulation: Once oxygenated blood returns to the left atrium, it is pumped by the left ventricle out to the body via the aorta, the largest artery in the body. This oxygen-rich blood delivers oxygen and nutrients to tissues throughout the body, and then deoxygenated blood returns to the right atrium via the superior and inferior vena cavae to start the process again.
These two circuits function together to ensure that oxygenated blood is delivered to all cells in the body and that deoxygenated blood is efficiently transported to the lungs for oxygenation. This dual circulation system is essential for maintaining proper oxygen levels in the body and for the overall function of the cardiovascular system. Hence, it is called double circulation.
