In human beings, the blood goes through the heart twice during each cycle i.e. the blood passes through the human heart two times to supply once to the whole body. So, it is called Double Circulation of blood.
Types of double circulation
The double circulation of blood includes:
(i) Systematic Circulation
(ii) Pulmonary Circulation
- Systemic circulation transfers oxygenated blood from left ventricles to capillaries in the tissue.
- The oxygen-rich blood is passed to the aorta for distribution into various body sections.
- The veins and venules later absorb the deoxygenated blood which is rich in carbon dioxide from different parts of the body.
- The deoxygenated blood is transferred back to the superior vena cava, then on to the right atrium.
- The right atrium transports blood to the right ventricle for pulmonary circulation, after receiving the deoxygenated blood.
- The distribution of blood starts in the pulmonary circulation from the right atrium to the left atrium.
- The pulmonary artery receives the blood from the right ventricle and carries to the lungs for oxygenation.
- When the oxygenated blood is pumped back to the left atrium via the pulmonary vein, that is brought to the left ventricles, after the purification process.
It is necessary for a human being to separate oxygenated and de-oxygenated blood because this makes their circulatory system more efficient and helps in maintaining constant body temperature.