In this article we are going to learn about circulatory system in human body. The proper working of the body depends on health. A healthy mind in healthy body, makes a human being perfect. Health and hygiene keep the body in a fit condition. , They also help in the proper functioning of the body. Apart from individual health and hygiene, health and hygiene of the community is also necessary For the health and hygiene of the body, we must know the various parts of the body and their functions. Blood circulates through the entire body. It transports different substances, from one part to another of the body. The circulatory system is an elaborate system of tubes called blood vessels through which blood circulates in the body. Heart pumps blood through blood vessels to various parts of the body.

Circulatory System :
The human body consists of many organs. Each organ is made up of number of cells. To do its work, each cell needs food, oxygen and other substances. In animals food is taken in through mouth and is digested in the alimentary canal (intestine). The digested food should be supplied from intestine to other parts of the body. Similarly, air containing oxygen enters into the lungs through nose. From lungs, oxygen should be supplied to other parts of the body. When the cell is doing its work, food is burnt to provide energy. In this process, waste products such as carbon dioxide are produced in the cells. These waste products should be sent out of the body. As most of the cells are situated deep in the body, they can not directly send the waste products out of the body. So, they should be transported to the body parts such as lung, kidney and skin which can send waste products out of the body. The distribution of food materials, oxygen and waste materials is done through blood. Blood circulates through the entire body in a system of closed tubes called blood vessels. Blood cannot flow by itself. It has to be pumped through blood vessels. Heart pumps blood through blood vessels. Blood vessels blood and the heart forms the circulatory system. Heart is the chief organ of the circulatory system which pumps blood to all the parts of the body. The circulatory system transports food, oxygen and other substances to the various parts of the body. It collects the waste materials from different parts of the body. Food is digested in the alimentary canal. The digested food enters into the blood through the inner wall of the small intestine. Blood distributes this digested food to the various parts of the body. Lungs are the respiratory organs. When air enters the lungs, the oxygen in the air enters into the blood through the wall of the lungs. The red blood corpuscles of the blood carry this oxygen and distribute it to various parts of the body. The carbon dioxide formed in the different cells is collected by the blood and is brought to the lungs to be expelled. The body requires energy for its activities. This energy is obtained by oxidising the food. This process is called respiration. During respiration, waste materials are formed. It is harmful if these waste materials remain in the body. The wastes are collected by the blood and carried to the kidneys. The kidneys eliminate these wastes in the form of urine.