Solution :
DOUBLE CIRCULATION in the HUMAN HEART
A mechanism in which blood circulates twice through the heart in one complete cycle is known as double circulation.
There are two pathways in which the blood flows in double circulation.
i) Systemic circulation and
ii) Pulmonary circulation
Double circulation is present in Aves and mammals.
Systemic circulation:
a) There is a systemic circulation flow of blood between the heart and bodily tissues.
b) The oxygenated blood flows from the left ventricle to all body parts.
c) The deoxygenated blood returns from the body tissue to the right atrium of the heart.
d) systemic circulation delivers nutrition, oxygen, and other vital elements to tissues while also transporting CO2 and other toxic substances for removal.
Pulmonary circulation:
a) Pulmonary circulation is present between the heart and the lungs.
b) The right ventricle pumps blood into the pulmonary artery, while the left ventricle pumps blood into the main aorta.
c) The impure (deoxygenated) blood pumped into the pulmonary artery is delivered to the lungs,
d) where it is replaced by pure ( oxygenated) blood carried into the left atrium via the pulmonary veins.