Ventilation
- Ventilation can be defined as
- The replacement of older air in the lungs with fresh air from the body's external environment
- Ventilation is essential for the effective exchange of gases in the lungs
- The exchange of oxygen and carbon dioxide occurs between the alveoli and the capillaries in the lungs
- Gases are exchanged by simple diffusion which requires a concentration gradient
- This gradient is maintained by
- Ventilation
- The continuous flow of blood in the capillaries
The impact of ventilation
- Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in the alveoli and blood flowing in adjacent capillaries
- Breathing in fresh air from the surrounding environment increases the concentration of oxygen in the air inside the alveoli
- Breathing out removes carbon dioxide
- This means that after ventilation, compared to the blood found in adjacent capillaries, the alveoli have
- Higher oxygen levels
- Lower carbon dioxide levels
- This ensures that oxygen continues to diffuse from the alveoli into the capillaries, while carbon dioxide continues to diffuse from the capillaries into the alveoli
- Both gases move down their concentration gradient
Ventilation maintains a concentration gradient between the air in the alveolus and the blood in the adjacent capillary