Lung Function and Specialised Cells

Question 1

What 3 features do gas exchange surfaces have?

Answer 1

1. They have a large surface area, which increases the rate of diffusion.
2. They’re thin (often just one layer of epithelial cells) - this provides a short diffusion pathway across the gas exchange surface, which increases the rate of diffusion.
3. The organims also maintains a steep concentration gradietn of gases across the exchange surface, which increases the rate of diffusion.

Question 2

What 4 features do Lungs have?

Answer 2

1. Many alveoli provide a large surface area for diffusion to occur across.
2. The alveolar epithelium and capillary endothelium are each only one cell thick, giving a short diffusion pathway.
3. All the alveoli have a good bloody supply from capillaries - they constantly take away oxygen and bring more carbon dioxide, maintaining the concentration gradient.
4. Breathing in and out refreshes the air in the alveoli, keeping the concentration gradients high.