Module 8: The structure and function of the cardiovascular system

The Body in Action

1. Introduction to the cardiovascular system
2. The heart
   1. Structure of the heart
   2. The heart valves
3. Labelling the heart activity
4. Circulatory system
   1. Animation of the circulation systems
5. Blood vessels
   1. Arteries
   2. Capillaries
   3. Veins
6. Characteristics of blood vessels activity
7. Function of the cardiovascular system
8. Function of the blood

Function of the cardiovascular system

The function of the cardiovascular system is to circulate blood through the network of vessels that run through the body. The purpose of this is to provide each cell with oxygen and nutrients needed to work, and to help dispose of waste products.

The oxygen rich blood leaves the heart via the arteries and delivers oxygen and nutrients to the body cells. The oxygen is used by the cells to produce energy, and in exchange the cells release waste products, including carbon dioxide and water. These waste products are carried in the oxygen poor blood back to the heart via the veins. The heart then pumps this blood to the lungs where carbon dioxide is 'unloaded' and exhaled and fresh oxygen is inhaled and 'taken up'. The now oxygen rich blood is carried back to the heart where the cycle can begins again.

As well as circulating oxygen around the body, and removing waste products, the cardiovascular system regulates body temperature. The process of ensuring the body temperature remains constant is called thermoregulation. Body temperature can be affected by the environment including the weather, through illness and by taking part in physical activity. It is important that body temperature is kept relatively constant, as extreme changes in temperature can affect the body's ability to function normally. To help keep the temperature relatively constant the blood vessels widen (vasodilation) to promote heat loss if the body gets too hot, and narrow (vasoconstriction) to conserve heat loss if the body gets too cold.