Lungs Gas Exchange

Question 1

Describe what happens to the diaphragm between times P and Q to bring about the change in its shape.

Answer 1

1. Flatten/moves down

2. Diaphragm muscle contracts

Question 2

Air moves into the lungs between times P and Q. Explain how the diagram causes this.

Answer 2

1. Diaphragm contracts
2. Increases volume of thorax and decrease in pressure
3. Air moves from high to lower pressure

Question 3

Describe how oxygen in the air in the alveoli enters the blood im capillaries

Answer 3

1. Diffusion

2. Across cell thick alveoli epithelium and then the capillary epithelium

Question 4

Describe and explain the mechanism that causes forced expiration

Answer 4

1. Contraction of internal intercostal muscles
2. Relaxation of diaphragm muscles
3. Causes decrease in volume of chest
4. Air pushed down concentration gradient

Question 5

Using data from the first second of forced expiration, calculate the percentage decrease in the FEV for group B compared with A.

Answer 5

19%

Question 6

Explain how an asthma attack caused the drop in the mean FEV shown in the figure above.

Answer 6

1. Bronchioles contract
2. Bronchioles secrete more mucus
3. Diameter of airways reduced
4. Therefore flow of air reduced

Question 7

Name organs P and Q

Answer 7

P = trachea 
Q = bronchus

Question 8

Explain how downward movement of the diaphragm leads to air entering the lungs

Answer 8

1. Increases volume in lungs/thorax
2. Lowers pressure in lungs
3. Air pushed by higher outside pressure