i)Explain briefly the structure of the human heart.

(ii) With the help of a neat, labelled diagram, explain the process of circulation in human beings.

Hey there!As answered previously:-

( i )

In human beings, the heart is a muscular organ. It is divided into four chambers right auricle, right ventricle, left auricle, and left ventricle. The walls of these chambers are made up of a special muscle calledmyocardium, which contracts continuously and rhythmically to distribute blood to all the body cells.

Flow of blood in the human heart

• The heart has superior and inferior vena cava. They carry deoxygenated blood from the upper and lower regions of the body respectively and supply the deoxygenated blood to the right auricle of the heart.

• The right auricle contracts and passes the deoxygenated blood to the right ventricle, through an auriculo-ventricular aperture (tricuspid valve).

• The right ventricle contracts and passes the deoxygenated blood into the two pulmonary arteries, which pumps it to the lungs where the blood is oxygenated. From the lungs, the pulmonary veins transport the oxygenated blood to the left atrium of the heart.

• The left atrium contracts and through the auriculo-ventricular aperture (bicuspid valve), 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.

Since the blood goes twice through the heart, it is known asdouble circulation.

(ii)

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 O₂for 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.