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

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

1. The left atrium receives the oxygenated blood from the lungs via the pulmonary veins.
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 it to all parts of the body except the lungs. When oxygenated blood passes through the capillaries of various organs, it delivers oxygen to the body’s cells. Along with oxygen, blood also delivers digested food and other dissolved substances to the body’s 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 returned to the lungs via the pulmonary artery for oxygenation.
6. The oxygenated blood is again sent to the left atrium of the heart by the pulmonary vein for circulation in the body.
7. The whole process repeats again and again, so that the blood keeps circulating throughout the body, delivering oxygen, digested food, and other materials to all parts of the body. This blood also continues to remove waste products (in the form of deoxygenated blood) formed in the body’s cells.