1. The respiratory system

2. Lung structure and function
VCE Unit 1 Biology
Respiration
Lung structure and function

3. Structure of the respiratory system?
Air enters the nose/mouth
Air travels _______
Air reaches major bronchi
Air then gets fed through a number of smaller tubes called the _____________
Air eventually reaches the _____

4. Functions of the upper airway
Nose, larynx and trachea
Warms and ____________ inspired air
Traps & eliminates foreign particles – involved in coughing
Not involved in __________________

5. Functions of the lower airway
From the ________to __________
Secrete mucus to catch foreign material
Cilia (hair-like structure on top of cell) can beat to push mucus back up airways where it can be coughed out

6. The alveoli are the site of gas exchange
There are approximately __ _____ alveoli in our lungs
The look a bit like a bunch of grapes
If you spread out each of these alveoli, they would take up an entire ________ ________!

7. Alveoli are surrounded by capillaries
Why do you think this is the case?

8. Alveoli are surrounded by capillaries
Answer:
Capillaries ensure that the breathed “air” is brought into close proximity to the “pulmonary” blood.
This allows _________ ____ _________ _________ ___ ___ ____ ____ _______.

9. Thin tissue separates blood from alveoli
________ ___ _______ walls are thin, permitting rapid _________ of gases.
Each RBC is only in lung capillary for 1 second
(RBC)

10. Answer the following in your workbooks
Where does gas exchange occur?
What structures does air pass through to get to the site of gas exchange?
What would happen if there was a thick gap between the alveoli and the capillaries?
Name a disease where the gap between the alveoli and capillary is increased.
What respiratory structure is affected in bronchitis and asthma?
Questions to be finished for homework and handed in next class

11. Respiratory muscles allow us to inspire
There are two phases in respiration (breathing): ________ ___ ________.
Inspiration (breathing in) allows gas to enter the lung
Expiration (breathing out) allows gas to exit the lung

12. The process of inspiration
Inspiration relies on the _________ and the rib muscles
The diaphragm is _ ____ ___ _____ that separates the chest cavity from the abdomen
During inspiration, the diaphragm and rib muscles ______. This increases the size of the chest cavity.
The increase in chest cavity size _______ _______ inside the chest.
As a result, the lungs are expanded and air is sucked in (just like a ______!)

13. The process of expiration
_______ occurs when the _____ ____
The lungs undergo a process called ______ which allows them to return to their original size
Recoil of the lungs occurs because the lungs are very elastic – just like an elastic band!
Question: what happens to an elastic band after you stretch it?

14. Muscles of Respiration
Expiration
Inspiration
Inspiratory muscles act to  chest volume
Diaphragm - major inspiratory muscle
Rib muscles – help the diaphragm to increase chest volume
The muscles relax
The lungs recoil because they are elastic

15. Lung expansion relies on intrapleural pressure.
How does increasing and decreasing thoracic volume alter lung volume?
The lungs are only attached at the hilus!
Lung expansion following increased thoracic volumes is dependent on _______ _________
Lung only attached at hilus

16. What is intrapleural space?
Each lung is attached to and surrounded by a thin ______ called a visceral pleural sac
The inside of the rib cage is also covered in a thin membrane called the parietal pleura
These two membranes are separated by the a thin layer of liquid known as the ________ ______
Imagine effects of drop of water between two glass sheets - easy to slide; hard to pull apart
Visceral pleura
Parietal pleura
Intrapleural space (-5cmH2O)

17. Why is intrapleural space important?
Visceral pleura
Parietal pleura
The pressure within the intrapleural space is negative (like a vacuum). This ______ ___ _____ _____ even though they want to collapse like an elastic band
When the chest expands during inspiration, the intraplueral pressure becomes even more negative and sucks the lung to the chest wall
This results in the lungs ________during inspiration

18. Loss of intrapleural pressure
Sheep diaphragm 18

19. What is in the air we breathe?
Atmospheric air contains mostly _______ gas and oxygen
Nitrogen makes up approximately _____ of air but is “inert”
Oxygen makes up approximately ___ __ __
Not much carbon dioxide is in atmospheric air – it only makes up a ____ percentage (0.0004%!)
Small amounts of water vapour and other gases are also present

20. What do our cells need? The cells in our body need ______ to survive
They use this oxygen in a process called __________ to create energy
A by-product of metabolism is the generation of _______ ______
Carbon dioxide can be _____ if it builds up in the body
Therefore, the lungs need to supply oxygen for our cells but remove carbon dioxide

21. How do the lungs do this? Via a process called “___ ________”
Gas exchange does not occur on a 1:1 basis (ie 1 molecule of oxygen is not exchanged for every molecule of carbon dioxide)
Rather the entry of oxygen into the blood and the removal of carbon dioxide occurs according to differences in ________ between the alveoli and blood
That is, it occurs via _______, down a __________ __________

22. What happens then?
Once oxygen diffuses across the alveoli, it enters the blood. Which components of blood carries oxygen?
Gases dissolve within the blood. They __ ___ ____ __ _______. (eg The bends in diving – what happens when bubbles of gas form in the body?)
The oxygenated blood travels to the heart and then around the body to the tissues/cells.

23. Blood goes to tissues and then returns to the lung
The oxygen diffuses down its concentration gradient to enter the tissues
Carbon dioxide concentrations are high in the cells. What do you think happens to the carbon dioxide here?
Blood returning to the lung is deoxygenated. What does this mean?
What happens to this blood at the lungs?
What happens to the blood then? Think back to your circulation lessons!

24. Diffusion of gases at the alveoli