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
It supplies oxygenated blood from the left auricle to left ventricle, thereby pumped 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 the blood into the right ventricle.
The deoxygenated blood is pumped by the right ventricle into the lungs for oxygenation. The oxygenated blood is brought back to the left atrium (auricle) of the human heart. From the left atrium, the oxygenated blood is pushed into the left ventricle. The left ventricle pumps oxygenated blood into the aorta for systematic circulation.
It is necessary for a human being to separate oxygenated and de-oxygenated blood because this makes their circulatory system is more efficient and helps in maintaining constant body temperature.