The circulatory system of the human body comprises of the heart and the blood vessels. It is responsible for moving the blood throughout the body. It also helps in the transportation of various components, including oxygen, water and various essential nutrients required by cells for their growth and development.

The circulatory System consists of three major parts-the heart, blood and blood vessels. The heart has the most important role to play. It is a muscular organ positioned in the middle of our chest, a little towards left. It performs function of pumping the blood throughout the body. Its size is about a human fist.

Circulatory system

Blood is substance that constantly flows through the body. It is a red colored liquid that has amount of both oxygen and carbon-di-oxide. It travels through thousands of blood vessels which are in our body. Blood carries oxygen, water, nutrients and waste products to and from body cells.

Types of Blood Vessels
There are three types of blood vessels - red blood cells, white blood cells and platelets.

Red Blood Cells are accountable for carrying carbon dioxide and oxygen. It carries oxygen from the lungs and transfers it to all cells in the body. After that, it gathers carbon dioxide from body cells which is the waste gas produced by the body cells while they are working. This waste gas is then transported back to the lungs from where it is removed from the body while we breathe out. One drop of blood contains about 5,000,000 red blood cells.

White Blood Cells are also known as Germinators as they help in fighting the germs which invade the body. It attacks and destroys germs which penetrate into the body and make it weak. When body catches some infectious disease there is a supplementary production of white blood cells in the body. Sometimes these White Blood Cells need external help and so antibiotics are prescribed by the doctor to help white blood cells in performing their function efficiently.

Platelets are blood cells that help in stopping the blood from bleeding. They also help in healing the wounds as Blood platelets plug up the holes from where the blood is leaking by sticking to the aperture of the spoiled blood vessel. Due to this gathering of blood platelets at the opening of the spoiled blood vessel the wound stops bleeding.

Plasma is known as the liquid part of the blood. Plasma constitutes about half of our bloods content. It is responsible for carrying the blood cells and other components throughout the body. Plasma is formed in liver. The Red Blood Cells, White Blood Cells and Platelets are produced in the bone marrow which is a spongy tissue inside our bones.