The circulatory system is one of the many systems in the bodies of various organisms.  The blood, the heart, and the blood vessels all define the circulatory system. Circulatory system is an essential feature of large, multi-cellular organisms, including humans (Whittemore & Cooley, 2004). The heart pumps blood through a network of blood vessels in the organism’s body. This paper highlights five principal roles of the circulatory system.Functions of the Circulatory System Essay

Firstly, the blood plays a key role in respiration. Respiration can be defined as the inhalation of oxygen and exhalation of toxic carbon dioxide from the body. Most of the body cells are not in contact with the oxygen, as the lung cells are. Therefore, since every living cell requires oxygen, the blood plays a significant role in delivering oxygen to these cells (Whittemore & Cooley, 2004). During inhalation, air enters the lungs and oxygen diffuses through its membranes into the bloodstream. Blood, rich in oxygen, goes through the heart before the heart pumps it throughout the body. On the other hand, carbon dioxide is harmful to the body. Blood carries carbon dioxide rich blood from all body cells to the respiratory organ, lungs, for exhalation. Through these actions, circulatory system helps in respiration (Whittemore & Cooley, 2004).Functions of the Circulatory System Essay

Secondly, blood supplies all the cells in the body with nutrients and energy from the food we consume. After full digestion of ingested food, the nutrients from the food are absorbed into the bloodstream through the gastrointestinal walls. The blood then transports nutrients to all the cells in the body. From the main powerhouse of the body, liver, blood also transports stored glucose to all cells (Whittemore & Cooley, 2004).

The third function of the circulatory system is a fighting disease. White blood cells in the body have the ability to detect foreign material and fight against it. When other organs of the body produce immune cells, the circulatory system also plays a vital role of transporting these cells to the various parts of the body where there is infection.

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The circulatory system also regulates body temperature. When the temperature rises, blood vessels dilate, to increase the lose of heat to the outside environment through the skin. The blood vessels contract moving farther away from the skin to reduce heat loses through the skin, when temperatures drop (Whittemore & Cooley, 2004).Functions of the Circulatory System Essay

The circulatory system has other functions, which include transport of hormones. Hormone is body communication signal produced by a specific organ for a specific information relay. Blood also carries toxic substances from production sites in the body to excretion organs (Whittemore & Cooley, 2004).

In conclusion, circulatory system plays a crucial role in the survival of all organisms. The network of blood vessels in the body ensures that the blood reaches all cells in the body. The heart also gives the necessary force to ensure that blood circulates irrespective of the distance of cell from the heart. This cordial working together of the circulatory system ensures that organism respire, excrete and that cells receive nutrients and energy, among other things.Functions of the Circulatory System Essay