Question 11:
Describe double circulation in human beings. Why is it necessary?
Answer
The human heart is divided into four chambers − the right atrium, the right ventricle,
the left atrium, and the left ventricle.
Flow of blood in the heart:
• The heart has superior and inferior vena cava, which carries de-oxygenated blood
from the upper and lower regions of the body respectively and supplies this de-
oxygenated blood to the right atrium of the heart.
Flow of blood in the human heart
• The right atrium then contracts and passes the de-oxygenated blood to the right
ventricle, through an auriculo-ventricular aperture.
• Then the right ventricle contracts and passes the de-oxygenated blood into the two
pulmonary arteries, which pumps it to the lungs where the blood becomes
oxygenated. From the lungs, the pulmonary veins transport the oxygenated blood
to the left atrium of the heart.
• Then the left atrium contracts and through the auriculo-ventricular aperture, the
oxygenated blood enters the left ventricle.
• The blood passes to aorta from the left ventricle. The aorta gives rise to many
arteries that distribute the oxygenated blood to all the regions of the body.
Schematic diagram of blood circulation in humans
Therefore, the blood goes twice through the heart. This is known as double circulation.
Importance of double circulation:
The separation of oxygenated and de-oxygenated blood allows a more efficient
supply of oxygen to the body cells. This efficient system of oxygen supply is very
useful in warm-blooded animals such as human beings.
As we know, warm-blooded animals have to maintain a constant body temperature
by cooling themselves when they are in a hotter environment and by warming their
bodies when they are in a cooler environment. Hence, they require more O2 for
more respiration so that they can produce more energy to maintain their body
temperature. Thus, the circulatory system of humans is more efficient because of
the double circulatory heart.
Latest Govt Job & Exam Updates: