Multiple choice

How is the exchange of gases able to take place within the capillaries?

  1. their walls are extremely thick

  2. their walls are only one cell thick

  3. they are very porous

  4. they are located closer to the veins

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Capillary walls are composed of a single layer of endothelial cells, which minimizes the distance gases must diffuse to move between the blood and tissues.