1. Gas Exchange

2. Gas Exchange (cont’d) Look back at the aerobic respiration equation.
What 2 substances are needed?
What 2 substances are the waste products?

3. Gas Exchange (cont’d)
In organisms there are places where oxygen enters and carbon dioxide leaves.
When one gas enters and another gas leaves, that surface is for Gas Exchange
These surfaces have certain characteristics

4. Characteristics of GE surfaces
The surface must be:
Permeable / thin enough to allow for diffusion

5. Characteristics of GE surfaces
The surface must be:
2) Close to an efficient transport system to take the gases away.

6. Characteristics of GE surfaces
The surface must be:
3) Kept moist, to stop cells from drying out and dieing.

7. Characteristics of GE surfaces
The surface must:
4) Have a large surface area, so that a lot of gas can diffuse at the same time.

8. Function (physiology)
Lung
Spongy, air-filled organs that are on either side of the heart.
EXTRA CREDIT: go to youtube.com
search for “balloon lung model”
Watch videos, create model, share with class.

9. Lung

10. Function (physiology)
Trachea:
Pipe to supply the lungs with air.
Supported by rings of cartilage.

11. Trachea
Lung

12. Function (physiology)
Larynx
Also known as the voice box
Can tighten muscles known as vocal cords, as air passes over
these muscles they
vibrate, producing
sound.

13. Larynx
Trachea
Lung

14. Function (physiology)
Bronchi
Around your heart, the trachea splits into 2 tubes. These two branches are called the left and right Bronchi. (singular: bronchus)
One bronchus goes into each lung, and then continue to branch into even smaller tubes.

15. Larynx
Trachea
Lung
Bronchi

16. Function (physiology)
Bronchioles
Tubes that branch off the bronchi, ending in tiny air sacs called alveoli.

17. Larynx
Trachea
Lung
Bronchioles
Bronchi

18. Function (physiology)
Alveoli
At the end of each bronchiole are many tiny air sacs called alveoli.
This is where gas exchange ACTUALLY TAKES PLACE.
Surrounding the alveoli are capillaries, tiny blood vessels. Oxygen diffuses from the alveoli into the capillary, CO2 is opposite.

21. What are we really breathing?
The composition of exhaled air (air that is breathed out) is very different from the composition of inhaled air (air that is breathed in).

22. Composition of Air
Inhaled air has the same composition as normal air, it contains:
78% nitrogen
21% oxygen
1% inert gas such as argon
0.04% carbon dioxide
little water vapor
Exhaled air is saturated with water vapor, it contains:
78% nitrogen
17% oxygen
1% inert gas such as argon
4% carbon dioxide
saturated with water vapor