2g

Question 1

Thorax

Answer 1

the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes.

Question 2

Role of intercostal muscles and diaphragm

Answer 2

Breathing in: Increase volume
External intercostal muslces contract to move ribs up and out
Diaphragm contracts and moves down

Breathing out: Decrease volume
External intercostal muscles relax to move ribs down and in
Diaphragm relaxes and moves up

Question 3

Alveoli adaptation

Answer 3

• They have a large surface area for diffusion
• Fluid to help dissolve gases and increase diffusion rate
• A rich blood supply to maintain a steep diffusion gradient between the alveoli and the blood.
• 1 cell thick so there is a short diffusion distance

Question 4

Effect of smoking (lungs, circulatory system and coronary heart disease)

Answer 4

• Tar in cigarettes destroy the Cilia therefore causing the buildup of Mucus and increasing risk of Bronchitis
• Tar decreases the surface area for gas exchange
• Nicotine in cigarettes causes blood vessels to narrow, placing strain on circulatory system and results in the increase in blood pressure