7)COPD

Question 1

Describe the signs and symptoms that a person with chronic bronchitis would experience (max 4 marks)

Answer 1

Persistent chronic cough
Shortness of breath on excursion
Chronic hypoxia (low O2)
hypercapnia (high O2)

Question 2

Describe the signs and symptoms that a person with emphysema would experience (max 4 marks)

Answer 2

Breathlessness
Barrel chest
Non productive cough
Weight loss

Question 3

List 4 of the main causes of Chronic Obstructive Pulmonary Disease

Answer 3

Cigarette smoking
Alpha-1 antitrypsin (AAT deficiency)
Indoor fuel burning
Air pollution

Question 4

Briefly explain how proteases are involved in the pathogenesis of chronic bronchitis in COPD.

Answer 4

proteases are release from respiratory epithelial cells, macrophages or neutrophils. Proteases have 3 effects: 1) Cause an increase in mucous production from goblet cells/ mucous glands leading to mucous hyper secretion 2) Protease degrades dyein protein in cilia which prevents them moving through the mucous. 3) Protease also inhibits the function of the ion transporter proteins on epithelial cells making the mucous dehydrated and more vicious.

Question 5

Explain the role of goblet cells in the pathogenesis of chronic bronchitis (4 marks)

Answer 5

Goblet cells are a defence mechanism of the innate immune system that produce mucous. They are present in epithelial cells lining the respiratory tract. Mucous enables the trapping of pathogens that enter the lung. In chronic bronchitis, protease causes an increase (hyperplasia) of goblet cells resulting in an increase (hyper secretion) of mucous.

Question 6

A smoker develops damage to several alveoli where the alveolar walls break down, leading to larger airspaces. How does this affect gas exchange?

Answer 6

Due to alveolar walls breaking down gas exchange will reduce as there is less surface area available. There is less elastin in the alveolar walls so this reduces there compliance. Low compliance means there is less air released in expiration, leading to air trapping. Due to this CO2 in alveoli will increase, this will lower the diffusion rate of CO2, reducing gas exchange.

Question 7

Describe what is meant by the term “lung compliance” and explain why this is important for normal gas exchange.

Answer 7

Lung compliance refers to the ability of lung tissue to stretch and recoil. It is determined by the surface tension of the alveoli and their elastic/ flexible walls. The recoil in compliance is needed to push air out of the lungs. Pushing air out helps lower the CO2 concentration in alveoli, helping to maintain a high CO2 concentration gradient between the returning blood and the alveolar space for rapid diffusion of CO2 from blood to alveoli.

Question 8

Explain the role of macrophages in the pathogenesis of COPD (4 marks)

Answer 8

In response to inflammatory cytokines from damaged epithelial cells, macrophages release protease and recruit neutrophils into the airways which also secrete proteases. Protease normally digest and destroy invading bacteria. In COPD , protease increases the production of think and viscous mucous and destroy the dynein protein in cilia. protease also breakdown the elastin and collagen in alveolar walls.

Question 9

Briefly explain how smoking leads to the pathogenesis observed in emphysema.

Answer 9

Toxins damage respiratory epithelial cells leading to a inflammation response. This leads to the activation of macrophages and the recruitment of neutrophils which also recruit proteases. Protease breaks down the elastin in alveoli leading to 1) permanently enlarged air spaces and 2) loss of elastin recoil (compliance) .