A physical process by which oxygen is taken in and carbon dioxide is given out is called breathing.
Steps of breathing:
- Ribs get moved up when we breathe in and flatter-r the diaphragm due to which the chest cavity becomes larger. Hence, the air is sucked into the lungs and fills the expanded alveoli.
- Haemoglobin binds with the oxygen and carries it along the blood in the body. Oxygen from the blood diffuses into the cell as the blood moves through the tissues.
- Carbon dioxide which is produced during respiration diffuses into the blood and is carried to the lungs for expiration.
- Ribs move down and diaphragm becomes dome-shaped decreasing the chest cavity. Thus, pushing the air out from lungs.