Gas exchange in the lungs

What this chapter teaches

In the lungs, oxygen passes from tiny air sacs into the blood, and carbon dioxide passes out of the blood into the air sacs. The walls are very thin and the blood is very close. Breathing moves air in and out of the lungs. Respiration is what every cell does with the oxygen, to release energy. Smoke harms the lungs, and smoke from tobacco and from cooking fires indoors is a real danger.

Three questions to ask

There is no one right wording. Listen for the idea.

1. Where does the oxygen in the air go when you breathe it in?
2. What is the difference between breathing and respiration?
3. How could a family make the smoke from a cooking fire less harmful?

After the chapter, the learner can

• Explain how oxygen enters the blood and carbon dioxide leaves it
• Explain how smoke from tobacco and cooking fires harms the lungs