1. On wbs write out a flow diagram
showing the route that O2 and CO2
gas takes

3. Structure of lungs and exchange
• Label the diagram to show the following:
– Red blood cells, capillaries, alveoli, air in , air
out, Thin cell wall
• Colour in the arrows RED for the movement of
oxygen and BLUE for the movement of carbon
dioxide
• Describe and explain 3 adaptations of the
alveoli for efficient gas exchange.

4. How are alveoli adapted?
Alveoli have several adaptations that help to make gas
exchange very efficient:
 They are very thin – only one cell thick.
 They are covered by a network of fine capillaries, enabling
gases to pass almost directly between the lungs and
bloodstream.
 They are moist, encouraging gas molecules to easily
dissolve.
 They have a large combined surface area, allowing large
amounts of gases to be exchanged with each breath.

5. Ventilation
Lesson objectives
• All will be able to describe the ventilation
process
• Most will be explain how muscle bring about
changes in pressure
• Some will be able to evaluate the limitations
of the lungs in the bell jar as a model for
ventilation

6. What are the differences between inhaled and exhaled air?
inhaled air exhaled air
nitrogen (78%) nitrogen (78%)
oxygen (21%) oxygen (17%)
carbon dioxide (0.04%) carbon dioxide (4%)
other other

7. Ventilation
• How does inhaled and exhaled air differ?
• Can you explain why there are these
differences?
Gas Inhaled Exhaled
Oxygen
Carbon dioxide
Nitrogen

8. Ventilation
• How do we get the oxygen and rid of carbon
dioxide?
• Breathing in is also known as inhalation.
• Breathing out is also known as exhalation

9. Ventilation
• Place hand on your ribs and
breathe in – what happens?
• What do the different parts
in the bell jar represent?
• How does air get drawn into
the lungs?

10. Ventilation

11. Ventilation
• Complete the statements to show how we
inhale air
– The intercostal muscles (between the ribs)
contract/relax
– The rib cage moves …… and …… and the
diaphragm flattens.
– The volume of the thorax (chest)
increases/decreases
– Causing the pressure to increase/decrease
– Air ……………………………….

13. Ventilation
• Now write your own flow diagram showing
what happens when we breathe out…

14. Ventilation
• Complete the statements to show how we
exhale air
– The intercostal muscles (between the ribs)
contract/relax
– The rib cage moves …… and …… and the
diaphragm becomes domed.
– The volume of the thorax (chest)
increases/decreases
– Causing the pressure to increase/decrease
– Air ……………………………….