1. Growth and Development of different organisms
National 5 Biology
Key Area 6:
The Need for Transport
(b) Animal Transport Systems
National 4 Biology
Key Area 4
Growth and Development of different organisms

2. By the end of this lesson you will be able to ....
Name the different parts of the respiratory system
Describe the function of rings of cartilage in the airways
Describe the structure of the alveoli
Describe the self-cleaning mechanism present in the lungs.

3. Structure of the Lungs Windpipe (trachea)
Has rings of cartilage around it
These rings help to keep the windpipe open!

4. Structure of the Lungs Bronchi (plural) Bronchus (singular)
Connects the windpipe to the lungs
Also contains cartilage

5. Structure of the Lungs Bronchioles
Smaller tubes which branch out throughout the entire lung
End in air sacs

6. Structure of the Lungs Air sac (alveolus) Air sacs (alveoli)
As small as a grain of salt!
Completely surrounded by blood capillaries
SITE OF GAS EXCHANGE!

8. TASK: label your diagrams
Structure of the Lungs
WORD BANK:
Trachea
Bronchus
Bronchiole
Alveoli (Air sacs)
Lung
Rings of cartilage

9. Air sacs are covered with blood capillaries
A single air sac
Each air sac is a
hollow, thin-walled
sac that is covered with
Capillaries.
This is where gas
exchange takes place
in the lungs
Oxygen enters the blood
Carbon dioxide leaves the blood
Bronchioles
Air sacs

10. Gas Exchange in an Alveolus
Oxygen and carbon dioxide are exchanged through the alveolar walls
Deoxygenated blood enters
Alveolus is ONE CELL THICK
Layer of moisture
Alveolus
(air sac)
CO2 out
O2 in
oxyhaemoglobin
Oxygenated blood leaves
Dense blood capillary network

11. HIGH CONCENTRATION of CO2 LOW CONCENTRATION OF CO2
Alveolus
HIGH CONCENTRATION of CO2
LOW CONCENTRATION OF CO2
HIGH CONCENTRATION O2
Blood capillary
LOW CONCENTRATION of O2

12. Why are the alveoli so good at Gas Exchange?
Alveoli have a large surface area
Alveoli have thin walls (only 1 cell thick!)
Alveoli have a good blood supply (surrounded by a dense network of blood capillaries)
All of the above allow for more efficient diffusion of gases.
Diffusion is the movement of a substance from an area of high concentration to an area of low concentration

13. Add the arrows to your diagram!

14. Add the arrows to your diagram!
HIGH CONCENTRATION of CO2 in blood
LOW CONCENTRATION OF CO2
HIGH CONCENTRATION O2
LOW CONCENTRATION of O2 in blood

15. Diffusion of Gases in the alveolus
There is a high concentration of carbon dioxide in the blood capillary and a low concentration in the alveolus, SO carbon dioxide will diffuse OUT of the blood capillary and INTO the alveoli
There is a high concentration of OXYGEN in the ALVEOLUS and a low concentration in the BLOOD CAPILLARY, so OXYGEN will diffuse OUT of the ALVEOLUS and INTO the BLOOD CAPILLARY

16. Healthy lungs! How are the lungs kept clean?
Why are the lungs ‘shiny’ looking?
Are the lungs wet or dry?
What makes them like this?
MUCUS

17. Mucus Mucus is a sticky substance that lines our respiratory tract
It traps dirt particles and micro-organisms like bacteria and some viruses

18. Microscope Slides Of Cilia
light microscope slide
(X1000)
electron microscope slide
X500,000
movement of cilia

19. Cilia hairs

20. Special features of the lungs
Rings of Cartilage
This helps to keep the main airways (trachea and bronchi) open and prevent them from collapsing
Mucus and Cilia
These help to keep the lungs clean
Mucus traps dirt and microorganisms and the rhythmic movement of the cilia beat the mucus up and away from the lungs
Stick in your diagram!

21. How do the lungs keep themselves clean?