Gas Exchange

Question 1

Define diffusion.

Answer 1

• The net movement of particles down a concentration gradient (high to low)
• Movement continues until equilibrium is reached (evenly distributed)
• Passive process (no energy required)

Question 2

Why do gas exchange organs need a large surface area to volume ratio?

Answer 2

To exchange gases quickly

Question 3

How are lungs adapted for gas exchange?

Answer 3

• Lots of alveoli- large SA for diffusion
• Alveolar and capillary endothelium are one cell thick which creates a short diffusion pathway.
• Alveoli have good blood supply which maintains the concentration gradient (oxygen and carbon dioxide can be exchanged quickly)
• Inspiration and exhalation maintains concentration gradients
• Lungs have large SA:V allowing more gas exchange to take place

Question 4

What is Fick’s Law?

Answer 4

Rate of Diffusion = area of diffusion x difference in concentration/thickness of diffusion

P x A x (C1 - C2)/T