Gas Exchange Flashcards

All 6 cards in this deck

In the lungs, which gas diffuses from the alveoli into the blood, and which diffuses from the blood into the alveoli?

Oxygen diffuses from the alveoli into the blood; carbon dioxide diffuses from the blood into the alveoli.

State four adaptations of the alveoli for gas exchange.

Large surface area, walls one cell thick, moist lining, and a dense network of capillaries.

Why are the walls of an alveolus only one cell thick?

It gives a short diffusion distance (path) between air and blood, so oxygen and carbon dioxide diffuse faster.

What keeps the oxygen concentration gradient between the alveolar air and the blood steep?

Ventilation (breathing) constantly replaces the air in the alveoli, and continuous blood flow carries oxygenated blood away.

True or false? A person whose alveolar walls have been destroyed, leaving fewer and larger air spaces, has a smaller total surface area for gas exchange.

True. Less surface area means less oxygen diffuses into the blood each second.

True or false? Thickening of the alveolar wall, for example by fluid in the lungs, has no effect on the rate of oxygen uptake.

False. It increases the diffusion distance, so oxygen diffuses into the blood more slowly.