Pathophysiology of respiratory diseases Part 2

Question 1

What is COPD?

Answer 1

an umbrella term used for a mixture of chronic
bronchitis and emphysema, and encompasses a long-term,
progressive, and accelerated decline in respiratory function.

Question 2

What pathological features are observed within the airways of COPD patients suffering from chronic bronchitis?

Answer 2

1. Damage to cilia
2. Mucus hypersecretion
   -Increases goblet cells and mucus gland activation
3. Inflamed, swollen airway tissue and oedema
4. Weakened airway structure(loss of elastin) and loss of patency(airway collapse)

Question 3

What does impaired mucociliary clearance result in?

Answer 3

Impaired mucociliary clearance = increased
risk of infection = recurrent infection

Question 4

What does irritation of sensory neurons result in?

Answer 4

Cough

Question 5

What does decreased luminal area result in?

Answer 5

Increased airway resistance and airway obstruction

Question 6

What does loss of airway patency due to degradation of structure cause?

Answer 6

Loss of airway patency due to degradation of structure can cause airway obstruction

Question 7

How is a healthy alveoli like?

Answer 7

Elastin in surrounding alveoli provides radial traction to splint bronchioles to splint bronchioles against positive Palv.

Question 8

How is an alveoli like in a patient with COPD?

Answer 8

No/very little radial traction causing bronchioles to collapse

Question 9

What happens in emphysema?

Answer 9

Decreased surface area and perfusion
-This decreases gas exchange
There’s also a loss of elastin fibres
-This increases compliance and reduces recoil

Question 10

What are the effects of chronic respiratory failure on the body?

Answer 10

-Chronic alveolar hypoxia causes hypoxic vasoconstriction which is increased pulmonary vascular resistance
-This leads to pulmonary hypertension
-This can go on to increased right ventricular afterload which results in right ventricular hypertrophy
-Ultimately causing right heart failure

Question 11

What can chronic alveolar hypoxia cause to quality of life?

Answer 11

Can lead to hypoxaemia, hypercapnia, acidemia
-This results in decreased exercise tolerance, fatigue and reduced quality of life

Question 12

What is pneumonia?

Answer 12

infection of the lung parenchyma,
resulting in inflammation and oedema

Question 13

What is the pathophysiology of pneumonia-induced acute lung injury?

Answer 13

1. Weakening of host defence(e.g. following viral infection, damage to epithelium, or immune suppression)
2. Colonisation of alveoli by pathogens
3. Activation of macrophages and cytokine release(IL-6, IL-8, TNF-alpha)
4. This leads to recruitment of neutrophils into alveolar space, release or proteases and ROS
5. This ultimately leads to injury to alveolus and surrounding structures/

Question 14

What does alveolar injury lead to?

Answer 14

1. Alveolar injury leads to deposition of dead cells and proteins in alveolar wall (‘hyaline membrane formation’) which leads to impaired gas exhange.
2. Alveolar injury also causes disruption of endothelium and basement membrane disruption which causes fluid to accumulate in alveoli and/or interstitium causing impaired gas exchange
   -You can hear crackles in lung sounds
   -There’s also lung opacity on x-ray
3. This impaired gas exchange ultimately leads to hypoxaemia

Question 15

Why is hypercapnia avoided in alveolar injury and why does hypoxaemia remain?

Answer 15

Hypercapnia is typically avoided due to a reflex increase in ventilation, including better-functioning parts of lung. However hypoxaemia remains due to the resulting VQ
mismatch.

Question 16

What respiratory condition is enlargement of airspaces within the lung parenchyma suggestive of?

Answer 16

Emphysema