At an alveolus, blood arriving from the body has less oxygen and more carbon dioxide than alveolar air. Which movement occurs?
Both gases diffuse from alveolar air into blood.
Oxygen enters blood, while carbon dioxide enters the alveolus.✓Bonne réponse
Oxygen leaves blood, while carbon dioxide also leaves the alveolus.
The alveolus actively pumps both gases into blood.
Explication
Oxygen diffuses from alveolar air into the blood, while carbon dioxide diffuses in the opposite direction into the air sac. Both gases do not move into blood because their concentration gradients point in different directions.