Circulatory System Essay

4143 WordsAug 1, 201217 Pages
The Circulatory System Introduction The circulatory system comprises of the heart, the blood vessels and blood. It can be thought of as the body's internal transport system, carrying messages and materials from one part of the body to another. The system is also central to the maintenance of homoeostasis, being closely integrated with the processes which control nutrients levels and waste disposal as well as water and temperature regulation. The need for an internal transport system arose many millions of years ago when an increase in the size of multicellular animals became limited by the rate at which gasses and nutrients could be obtained from the external environment by simple diffusion. The development of a simple circulation meant that exchange could be managed by specialist organs such as the gut and lungs and the products of exchange transported to all of the cells of the body. It would be reasonable to suggest that without the development of the circulation system, animal life as we know it today would not exist - including ourselves…! The main functions of the circulatory system can be summarised as follows: * Transport of respiratory gasses. Oxygen is transported from the lungs to the tissues for use in energy production and carbon dioxide, a waste product of this process is transported from the tissues to the lungs for disposal to the atmosphere. * Transport of nutrients. Glucose, amino acids and other useful substances such as vitamins and minerals are absorbed by the gut are transported in the blood to tissues or sites of storage such as the liver. Fats absorbed in the digestive process are initially transported from the gut by the lymphatic system that eventually feeds into the circulatory system. Nutrients released from storage are also transported in the blood to tissues that need them. * Transport of metabolic wastes. During

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