Gas Exchange and Air Composition
This page focuses on the process of gas exchange in the lungs and the composition of inhaled and exhaled air.
Gas exchange in the lungs is a crucial process that occurs in the alveoli. This process, also known as gaseous exchange in humans, involves the transfer of oxygen from the air in the alveoli to the bloodstream and the removal of carbon dioxide from the blood to be exhaled.
Definition: Gas exchange is the process by which oxygen and carbon dioxide are transferred between the air in the alveoli and the blood in the surrounding capillaries.
The process of gas exchange occurs through diffusion:
- Oxygen moves from the air in the alveoli (where its concentration is high) into the bloodstream (where its concentration is lower).
- Carbon dioxide moves from the blood (where its concentration is high) into the alveoli (where its concentration is lower).
Highlight: Gas exchange occurs by the process of diffusion, which is the movement of molecules from an area of high concentration to an area of low concentration.
The composition of the air we breathe changes as it passes through the respiratory system:
-
Inhaled air:
- 21% Oxygen
- 0.03% Carbon dioxide
-
Exhaled air:
- 16% Oxygen
- 4% Carbon dioxide
Example: The significant increase in carbon dioxide concentration in exhaled air (from 0.03% to 4%) demonstrates the efficiency of the lungs in removing this waste gas from the body.
This difference in composition highlights the effectiveness of the respiratory system in supplying oxygen to the body and removing carbon dioxide.