Describe double circulation of blood in human beings.
Question.
Describe double circulation of blood in human beings. Why is it necessary?

solution:
Double circulation In double circulation, the blood passes twice through the heart to supply once to the body

(i) Systemic circulation In this, blood completes its circulation from left ventricle to right auricle through the body organs.(systemic organs)

Oxygenated blood from lungs $\rightarrow$ heart $\rightarrow$ Systemic arteries $\rightarrow$ Body parts $\rightarrow$ Systemic veins $\rightarrow$ heart

(ii) Pulmonary circulation In this, blood completes its circulation from right ventricle to left auricle through the lungs.

Deoxygenated blood from body $\rightarrow$ heart $\rightarrow$ Pulmonary arteries $\rightarrow$ lungs parts $\rightarrow$ Pulmonary veins $\rightarrow$ heart

The right portion of heart is known as pulmonary heart and it has deoxygenated blood. The left portion of heart is known as systemic heart and it has oxygenated blood. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature.
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