Efficient Gas Exchange

—> the alveoli are the site of gas exchange
—> are adapted to maximise gas exchange

To be an efficient gas exchange system :

• large surface area = fast gas exchange
• short diffusion pathways = enable quicker diffusion
• maintains concentration gradients

1. Alveoli walls are one squamous epithethlial cell thick 

- diffusion path is short 

- oxygen can get from the alveoli to the blood quickly 

2. Many alveoli in each lung 

- large surface area 

- more alveoli gives you more surface area 

- gas exchange is more efficient due to increase in surface area 

3. Alveoli have elastin in the walls 

- stretch out = increase in surface area 

- lungs can expand so alveoli can expand 

- increase in surface are so quicker gas exchange 

4. Capillaries are in close proximity to alveoli and capillary walls are one cell thick 

- shorter diffusion path 

- gas exchange will more efficient 

5. Capillaries take oxygenated blood away and brings deoxygenated blood to the alveoli 

- short diffusion pathways 

- maintains the concentrated gradient 

- diffusion is happening more quickly 

- constant movement of gas 

6. Surface of the alveoli are moist 

- maintains the conce gradient 

- enables diffusion to happen more quickly 

7. Alveoli produce surfactant 

- surfactant = reduces surface tension of water // prevents lyng from sticking together 

- larger surface area = increase in diffusion 

8. Ventilation draws air into lungs and removed air from lungs 

- maintains concentration gradient 

- diffusion is more efficient 

What would happen is there was damage to the alveoli walls or alveoli walls were lost? 

- the surface area inside the lung reduces 

- gas exchange will be less effiicent = less oxygen available to cells