Topic 3---A: Exchange and Transport Systems- 4. The effects of lung disease

Question 1

What do lung diseases effect?

Answer 1

• They affect both ventilation (inspiration and expiration) and gas exchange in the lungs.

Question 2

Definition of tide volume

Answer 2

Volume of air in each breath

Question 3

Definition of ventilation rate

Answer 3

The number of breaths per minute

Question 4

Definition of forced expiratory volume

Answer 4

The maximum volume of air that can be breathed out in 1 second

Question 5

Definition of forced vital capacity

Answer 5

The maximum volume of air it is possible to breath out of the lungs after a really deep breath in.

Question 6

Tuberculosis (lung disease)

Answer 6

• Lung disease caused by bacteria
• When someone becomes infected with tuberculosis bacteria the immune system cells build a wall around the bacteria in the lungs.
• This forms the small, hard lumps known as tubercles.
• Infected tissue within the tubercles dies and the gaseous exchange surface is damaged
• So tidal volume decreases meaning less air can be inhaled with each breath.

Question 7

Fibrosis (lung disease)

Answer 7

• It’s the formation of scar tissue in the lungs which is thicker and less elastic than normal lung tissue
• So the lungs are less able to expand so can’t hold as much air as possible
• So tidal volume is reduced
• Diffusion is slower across a thicker scarred membrane

Question 8

Asthma (lung disease)

Answer 8

• It’s a respiratory condition where the airways become inflamed and irrated.
• During an asthma attack, the smooth muscle lining of the bronchioles contracts and a large amount of mucus is produced
• This causes constriction of the airways making it difficult to breathe properly
• Air flow into and out of the lungs is reduced so less oxygen enters the alveoli and moves into the blood.

Question 9

Emphysema (lung disease)

Answer 9

• Caused by smoking or long-term exposure to air pollution
• Particles in the smoke or air become trapped in the alveoli
• This causes inflamation which attracts phagocytes to the area
• The phagocytes produce an enzyme that breaks down elastin which is a protein found on the walls of alveoli.
• A loss of elastin means alveoli can’t recoil
• Also leads to destruction of the alveoli walls reducing the surface area of the alveoli.

Question 10

How do lung diseases effect ventilation

Answer 10

• Reduced lung elasticty (e.g. fibrosis- build up of scar tissue) so lungs expand less so can’t hold as much air as normal so reduces the maximum volume of air breathed out in one breath.
• Narrow airways- reduces air flow in and out of lungs (asthma)
• Reduced rate of gas exchange

Question 11

How do different lung diseases reduce the rate of gas exchange

Answer 11

• Thickened alveolar tissue (fibrosis) so increases the diffusion distance
• Alveolar wall breakdown- reduces surface area
• Reduce lung elasticity- Lungs expand less reducing the concentration gradient of oxygen