CBSE Class 10 Answered

Internal respiration is the exchange of oxygen and carbon dioxide between blood and cells in different tissues of an animal's body. It happens in much the same way as gas exchange in the lungs i.e. through diffusion. Red blood cells carry the oxygen to the body, and brings back the carbon dioxide to the lungs.

The blood brings oxygen rich air to the cells of the body. The oxygen diffuses to the cells, which is deficient in oxygen. Then carbon dioxide from the cells diffuses to the blood vessels. This carbon dioxide is carried to the lungs for removal from the body. Oxygen is transported by haemoglobin of blood. Carbon dioxide on the other hand is more soluble in water than oxygen and hence is transported in dissolved form in blood.