Circulatory System:
Animals are comprised of trillions of cells and each cell in the body needs a supply of oxygen and nutrients in order to survive. To deliver these things and take away wastes, nearly all animals need a special transit system which is called Circulatory System. Materials formed in one part of the body have to be taken up to other parts where they are needed or to be got rid of. This is an essential requirement of most animals. This function is performed by the body fluids.
The movement of the body’s fluids, blood, and lymph from one part of the body to the other parts is called circulation. In lower organisms like the one called protozoans such as Amoeba and Paramecium. The cell is in direct contact with the surrounding water and there is a direct exchange of materials between the cell and the water. So, there is a need for a circulatory system.
Components of Circulatory System of Human:
The cardiovascular system consists of the heart, blood vessels, and the approximately 5 liters of blood that the blood vessels transport.
1. Heart: The heart is the organ that supplies blood and oxygen to all parts of the body. This amazing muscle produces electrical impulses through a process called cardiac conduction. These impulses cause the heart to contract and then relax, producing what is known as a heartbeat.
2. Blood Vessels: Blood vessels are intricate networks of hollow tubes that transport blood throughout the entire body. Blood travels from the heart via arteries to smaller arterioles, then to capillaries or sinusoids, to veins, and back to the heart.
3. Blood: The blood delivers nutrients to cells and removes wasters that are produced during cellular processes, such as cellular respiration. It is composed of red blood cells, white blood cells, platelets, and plasma.