Explain the link between respiration, nutrition and circulation.

Circulation links respiration and nutrition. Through nutrition nutrients are taken in by body which is absorbed in blood stream. Through respiration, exchange of gases takes place in blood. Both nutrients and gases are transported to cells and tissues of the body through blood by the process of circulation.

The mechanisms of inspiration (inhaling) and expiration (exhaling) are need for the absorption of oxygen gas into the lungs and removal of carbon dioxide from the body. When oxygen is inhaled, it diffuses into the blood capillaries and is carried by hemoglobin which is a component of the blood back to the heart in the pulmonary vein. The left ventricle of the heart then contracts which pushes the oxygenated blood around the body in the main blood vessel known as the aorta which divides into other smaller blood vessels. The oxygenated blood is transported to every cell of the body. De-oxygenated blood from the body travels back to the heart in the vena cava. This is called CIRCULATION and is what makes up the circulatory system.

The oxygen pumped around to the cells is used to assist the production of ATP in aerobic RESPIRATION. It is the final hydrogen acceptor in the oxidative phosphorylation stage of respiration. Without it the pH of the blood will be fatally low.

NUTRITION, involves the absorption of digested food substances that can be used as respiratory substrates as a source of hydrogen ions for respiration. Substances such as lipids and fats are a good source of H ions for respiration.