Question

Describe the working of the human blood circulatory system with the help of a suitable diagram that shows all the steps involved.

Answer 1

Working of human blood circulatory system:

The human blood circulatory system is composed of the heart, the blood and the blood vessels. The human heart is divided into four chambers. The upper two chambers are called right and left atrium and the lower two chambers are called the right and the left ventricles. Following are the steps involved in the blood circulation:

1. The left atrium receives the oxygenated blood from the lungs via the pulmonary vein.
2. When the left atrium contracts, the oxygenated blood is pumped into the left ventricle.
3. When the left ventricle contracts, the oxygenated blood is forced into the aorta, which transports the blood to all the parts of the body, except the lungs. When oxygenated blood passes through the capillaries of different organs, it gives oxygen to the body cells. Along with oxygen, blood also gives the digested food and other dissolved materials to the body cells. At the same time, carbon dioxide, which is produced as waste material during respiration, enters the blood.
4. From the body tissues, the deoxygenated blood carrying carbon dioxide is pumped back to the heart, into the right atrium, by the vena cava.
5. When the right atrium contracts, the deoxygenated blood is pumped into the right ventricle. From here, it is taken back to the lungs by the pulmonary artery for oxygenation.
6. The oxygenated blood is again sent to the left atrium of the heart by the pulmonary vein for being circulated in the body.
7. The whole process is repeated again and again so as the blood keeps circulating in our body and keeps circulating oxygen, digested food, and other materials to all the parts of the body. This blood also keeps on removing waste products (in the form of deoxygenated blood) formed in the cells of the body.