Gas Exchange in the Lungs Flashcards

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Where in the lungs does gas exchange take place?

Gas exchange takes place in tiny air sacs in the lungs called alveoli.

Oxygen moves from the air into the blood, and carbon dioxide moves from the blood into the air.

An alveolus is a small, round air sac in the lung with thin, moist walls where gas exchange happens.

Oxygen diffuses from the air in the alveoli into the blood in the capillaries, from high to low concentration.

Carbon dioxide diffuses from the blood in the capillaries into the air in the alveoli, from high to low concentration.

A large surface area lets more gas pass across at the same time, so oxygen and carbon dioxide are exchanged quickly.

There are millions of tiny alveoli, each balloon shaped and folded, so together they give a very large surface area.

They are one cell thick so the distance for diffusion is very short, which makes gas exchange fast.

Many capillaries bring blood past the alveoli. This keeps oxygen in the blood low and carbon dioxide high, so diffusion stays fast.

Gases dissolve in the thin layer of moisture, which helps them diffuse across the alveolus wall into or out of the blood.

It means there is a big difference in gas concentration between the air in the alveoli and the blood, so diffusion happens fast.