Question

What happens to Oxygen after it enters the lungs?

Answer 1

Each lung contains millions of alveoli. The walls of the alveoli are richly supplied with blood capillaries. The air which reaches the alveoli after passing through trachea, bronchi, bronchioles is rich in oxygen and contains very little CO₂. The blood capillaries of the alveoli contain blood that has more carbon dioxide and little oxygen. The oxygen diffuses from the thin walls of the capillaries into the blood and combines with hemoglobin in the red blood cells of blood thereby forming oxyhemoglobin. Hemoglobin is a type of protein which contains iron. The blood carries oxygen to all the cells of the body. In the cells, a series of chemical reactions, CO₂, water and energy are released. The carbon dioxide released combines with the hemoglobin to form carbomino hemoglobin. Then the blood rich in carbominohaemoglobin leaves the cells and reaches the alveoli where CO₂ gas is released and is exhaled out through the nose.