Gas exchange in the alveoli
Across a thin wall.
Inside the lungs
The lungs end in tiny balloon-like sacs with thin walls.
What happens between the air in the sacs and the blood around them?
What this lesson covers
The idea
The thin-walled alveoli are surrounded by fine tubes containing blood: carbon dioxide passes from the blood into the air in the alveoli, while oxygen passes into the blood and is carried to all parts of the body.
Inside the lungs
The lungs end in tiny balloon-like sacs with thin walls.
What happens between the air in the sacs and the blood around them?
- Oxygen goes into the blood and carbon dioxide comes out of it
- Nothing moves at all
- Food moves into the air
Exchange
Press Exchange. Watch the blue O2 rings and the grey CO2 rings.
Two gases swap places
Oxygen moved from the air in the alveolus into the blood. Carbon dioxide moved from the blood into the air in the alveolus.
The thin-walled alveoli are surrounded by fine tubes containing blood. Carbon dioxide passes from the blood into the air in the alveoli, while oxygen passes into the blood and is carried to all parts of the body.
Notes
The thin-walled alveoli are surrounded by fine tubes containing blood. Carbon dioxide passes from the blood into the air in the alveoli, while oxygen passes into the blood and is carried to all parts of the body.
Check yourself
Which gas passes from the alveoli into the blood?
Which gas passes from the blood into the alveoli?
What surrounds the alveoli?
Where is the oxygen carried after it passes into the blood?
- Carbon dioxide. Carbon dioxide passes from the blood into the air in the alveoli.
- Oxygen — correct. Yes!
- Dust. Dust is trapped in the nose by hair and mucus. Oxygen passes into the blood.
- Oxygen. Oxygen passes from the alveoli into the blood.
- Starch. Starch is a food component, not a gas.
- Carbon dioxide — correct. Yes!
- Fine tubes containing blood — correct. Yes!
- Teeth. Teeth are in the mouth. Fine tubes containing blood surround the alveoli.
- Bile. Bile is a digestive juice made by the liver. Fine tubes containing blood surround the alveoli.
- Only to the nose. Oxygen is carried to all parts of the body.
- To all parts of the body — correct. Yes!
- Back to the windpipe. The blood carries oxygen to all parts of the body, not back to the windpipe.