Question

How are oxygen and carbon dioxide exchanged in our body during respiration?

Answer 1

During respiration, oxygen and carbon dioxide are exchanged mainly in the lungs and body tissues through a process called diffusion.

In the lungs

• When we breathe in, air enters tiny air sacs called alveoli.
• The alveoli are surrounded by very thin blood capillaries.
• Oxygen concentration is higher in the alveoli than in the blood, so oxygen diffuses into the blood.
• At the same time, carbon dioxide concentration is higher in the blood than in the alveoli, so carbon dioxide diffuses into the alveoli.
• The carbon dioxide is then breathed out.

In the body tissues

• Blood carrying oxygen reaches body cells.
• Oxygen diffuses from the blood into the cells because cells need oxygen for energy production.
• Cells produce carbon dioxide as a waste product.
• Carbon dioxide diffuses from the cells into the blood and is carried back to the lungs.

So, the exchange occurs because gases move from an area of higher concentration to one of lower concentration through thin membranes.