Why blood is called the river of life? Blood carries oxygen and essential nutrients to body tissues and transports waste products away to be removed from the body. Living organism require substances such as oxygen and nutrients from the external environment for cellular activities. These activities produce toxic waste products that must also be removed. William Harvey (1578-1657) discovered that blood flows in a closed circulatory circuit in the body. His work laid the foundation for modern understanding of the cardiovascular system.
Circulatory System in Human
The circulatory system in a large organism such as humans involves flow of fluid through the tissues and organs, allowing transport and exchange of substances such as nutrients, oxygen and waste products. In humans, the circulatory system includes medium, vessels and pump. The medium is the fluid that flows in the circulatory system. It transports materials around the body. The blood in the body is carried by a system of large and small vessels. These are arteries, veins and capillaries. The pump in the body is the muscular heart. It creates the pressure that force s the blood through the blood vessels throughout the whole body. Nutrients and oxygen are carried by the capillaries to cells where the exchange of material occurs and waste products are carried away from the cells.
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