Question

Using what you know about particle theory, explain how oxygen diffises from an air sac into the blood

Answer 1

Explanation:

• Diffusion of oxygen into the blood takes place at the alveoli (air sacs). The alveoli are very close to capillaries, which are small blood vessels. The blood in the capillaries has very little oxygen and has a lot of carbon dioxide.
• The walls of both the alveoli and the capillaries are very thin and oxygen and carbon dioxide move along the concentration gradient. This movement is called diffusion.
• Oxygen diffuses from the alveoli, into the blood in the capillaries. Similarly, carbon dioxide from the blood moves out of the capillaries into the alveoli.