Explain Internal Respiration

What do you understand by the term 'internal respiration'? Well, the interchange of gases between the blood and cells of the body is internal respiration. The exchange of gases between the blood and tissues takes place between the arterial end of the capillaries and the tissue fluid. The process involved is termed as diffusion. Diffusion occurs from a higher concentration of oxygen in the blood to a lower concentration in the tissue fluid. Oxygen is dissolved in the plasma and is carried from the lungs to the tissues. Oxygen combines with haemoglobin to form oxyhaemoglobin. Oxyhaemoglobin breaks up easily to liberate oxygen.

Tissue cells need a constant supply of oxygen. Hence, diffusion of oxygen from the blood to the tissue fluid and then to the cells is continuous. The active cells receive more oxygen. When the cells become very active, there is a higher concentration of carbon dioxide. This helps in the release of oxygen from oxyhaemoglobin more rapidly. Carbon dioxide is one of the waste products of carbohydrate and fat metabolism. The mechanism by which carbon dioxide is transferred from the cells into the blood is diffusion which occurs at the venous end of the capillaries. Certain adjustments need to be made inside our body, to cope up with the varying environmental conditions.