1. Gas Exchange
Respiratory System

2. Distinguish between ventilation, gas exchange and cell respiration.
Ventilation: (in lung) The process of bringing fresh air into the alveoli and removing the stale air. It maintains the concentration gradient of CO2 and oxygen between the alveoli and the blood in the capillaries (vital for oxygen to diffuse into the blood from the alveoli and CO2 out of the blood into the alveoli).
Gas exchange: (in capillary) The process of swapping one gas for another. It occurs in the alveoli of the lungs. Oxygen diffuses into the capillaries from the air in the alveoli and CO2 diffuses out of the capillaries and into the air in the alveoli. 
Cell respiration: (in body cell) Energy is released in the form of ATP so that this energy can be used inside the cell. Cell respiration occurs in the mitochondria and cytoplasm of cells. Oxygen is used in this process and CO2 is produced.

3. Explain the need for a ventilation system.
To maintain the concentration gradients of oxygen and CO2 in the alveoli. 
The body needs oxygen to make ATP via cell respiration.
The body needs to get rid of carbon dioxide which is a product of cell respiration.
Oxygen needs to diffuse from the alveoli into the blood.
Carbon dioxide needs to diffuse from the blood into the alveoli.
To do so, there must be a high oxygen concentration and a low CO2 concentration in the alveoli. 
A ventilation system makes this possible by getting rid of the carbon dioxide in the alveoli and bringing in more oxygen.

4. Video with British Accent!!
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Video with British Accent!!

5. Describe the features of alveoli that adapt them to gas exchange.
Great numbers increase the surface area for gas exchange.
Wall consisting of a single layer of flattened cells.
Same as the capillary walls.
Therefore diffusion distance is small, allowing rapid gas exchange.
Covered by a dense network of capillaries which have low oxygen and high CO2 concentrations.
This allows oxygen to diffuse into the blood and carbon dioxide to diffuse out of the blood.  
Some cells in the walls secret fluid creating a film of moisture.
This allows gases to dissolve and prevents the sides of alveoli from sticking together.

6. Draw and label a diagram of the ventilation system.
Include the:
Trachea
Lungs
Bronchi
Bronchioles
Alveoli (as well as higher magnification of alveoli)

8. Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercostal muscles, the diaphragm and abdominal muscles.

9. Inhalation (inspiration)
The external intercostal muscles contract. This moves the ribcage up and out. 
The diaphragm contracts. As it does, it moves down and becomes relatively flat. 
Both of these muscle contractions result in an increase in the volume of the thorax which in turn results in a drop in pressure inside the thorax.
Pressure eventually drops below atmospheric pressure. 
Air then flows into the lungs from outside the body, through the mouth or nose, trachea, bronchi and bronchioles. 
Air continues to enter the lungs until the pressure inside the lungs rises to the atmospheric pressure.

10. Exhalation (expiration)
The internal intercostal muscles contract. This moves the ribcage down and in. 
The abdominal muscles contract. This pushes the diaphragm up, back into a dome shape. 
Both of these muscle contractions result in a decrease in the volume of the thorax. 
As a result of the decrease in volume, the pressure inside the thorax increases. 
Eventually the pressure rises above atmospheric pressure.
Air then flows out of the lungs to outside of the body through the nose or mouth. 
Air continues to flow out of the lungs until the pressure in the lungs has fallen back to atmospheric pressure.

11. More of the British Lady!!
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More of the British Lady!!