Question

What is double circulation? What is the benefit of double circulation?

Answer 1

Hint: In humans, during a cardiac cycle, blood passes through the heart twice. This is called double circulation. It is called so because deoxygenated blood passes through the heart. In addition, oxygenated blood also passes through the heart. Double circulation helps in ensuring a dedicated supply of oxygen to the body. Animals which have double circulation show an increase in activity.

Complete answer:
During double circulation, oxygenated blood is strictly separated from deoxygenated blood. So, this is a very efficient method of circulation of blood.
There are four chambers present in the human heart, namely, left atrium, right atrium, right ventricle and left ventricle.
There are two pathways in double circulation. They are as follows:
1. Systemic circulation
2. Pulmonary circulation
In systemic circulation, oxygenated blood is carried to aorta. Deoxygenated blood collected by veins is transferred to the superior vena cava and then to the right atrium. Now, the blood is carried by right atrium to right ventricle to proceed for pulmonary circulation. Its purpose is to carry oxygenated blood from left ventricle to tissue capillaries.
In pulmonary circulation, deoxygenated blood is collected by the pulmonary artery from the right ventricle and the blood is carried for oxygenation to the lungs. After purification is done, through the pulmonary vein, oxygenated blood is pumped into the left atrium and then to the left ventricle. Then the blood is pumped for systemic circulation by the left ventricles to the aorta.

Note:
Apart from the double circulation, a third portal is also present to provide improvement in circulation efficiency. It improves the body efficiency, because of which mammals are able to maintain the temperature of the body. Mammals and birds possess double circulation. They are highly energetic and are warm-blooded. Besides, double circulation provides the capacity to pump more blood due to the generation of high pressure.