1. Exchanging materials in the lungs
How do oxygen and carbon dioxide move into and out of the lungs and blood?
Resources: lungs, bell jar, dissection kit,
Starter:
Sulking! Put out your bottom lip as far as you can. Show your neighbour. How could you describe the blood vessels you can see.

2. Glossary Ventilated – movement of air into and out of the lungs.
Solute – The solid which dissolves in a solvent to form a solution.
Gaseous exchange – the exchange of gases e.g the exchange of oxygen and carbon dioxide which occurs between the air in the lungs and blood.

3. Getting air into and out of the lungs = ventilation
Bell Jar – discuss ventillation
Complete the task by filling in the gaps to explain inspiration and expiration.

4. The Lungs
Lets have a look
Body Model, Bell Jar , Actual lungs

5. The Alveoli – use this info to label your diagram.
Air moves into an alveolus during inspiration. This contains relatively high levels of oxygen and low levels of carbon dioxide. Blood entering the capillaries that surround the alveoli, comes from the heart and contains low levels of oxygen and high levels of carbon dioxide.
Concentration gradients are built up for these two gases.
Oxygen dissolves in the moist surface of the alveolus and diffuses into the blood, attaching to the blood cell.
Carbon dioxide diffuses across the thin capillary and alveolus wall, returns to gaseous form and is exhaled.
Blood that leaves the alveoli has a high concentration of oxygen and a low concentration of carbon dioxide.

6. Where does gas exchange occur?
The alveoli are adapted to make gas exchange in lungs happen easily and efficiently.
Features of the alveoli that allow gas exchange
They have moist, thin walls (just one cell thick)
They give the lungs a really big surface area
They have a lot of tiny blood vessels called capillaries.

7. An Alveolus

9. The gases move by diffusion.
How do the gases move?
The gases move by diffusion.
Diffusion is the process by where gases move from a high concentration to a low concentration:
Oxygen diffuses from the air in the alveoli into the blood.
Carbon dioxide diffuses from the blood into the air in the alveoli.
Capillary

10. Other ventilation systems
Common Musk Turtle

11. Task : complete the past paper questions