20. When Things Go Wrong in the Respiratory System

Question 1

Name the 3 types of respiratory diseases.

Answer 1

Obstructive

Restrictive

Infection & inflammation

Question 2

How is Airway resistance Measured?

Answer 2

Forced expiratory volume in 1 sec (FEV1) by spirometry

Question 3

Describe the effects of Chronic Obstructive Pulmonary Diseases (COPD)

Answer 3

• Narrowing airways = ↑airway resistance
• Elastic recoil of lungs lost = ↓outflow pressure

== ↓ FEV1

↑Residual Volume (RV) = appearance of chest over-inflation

Question 4

Name the 4 main Chronic Obstructive Pulmonary Diseases (COPD)

Answer 4

Chronic bronchitis
Emphysema
Narrowing
Recoil

Question 5

Describe Chronic bronchitis

Answer 5

• irritants cause inflammation in bronchi
• abnormal mucus secretion
• plugs airways
• prone to infection
  = further inflammation

Question 6

What is the result of Chronic Bronchitis?

Answer 6

• Airway obstruction
• Shortness of breath / wheezing,
• Chest pain, chronic (productive - sputum) cough

Question 7

Treatment of Chronic Bronchitis?

Answer 7

• Stop smoking
• Bronchodilators
• Antibiotics

Question 8

Describe Mechanism of Emphysema caused by smoking

Answer 8

Alveloar sacs are broken down.

1. Smoking
2. Neutrophils & Macrophages release elastase
3. Elastase destroys alveolar walls
4. Emphysema

Question 9

Describe Mechanism of Emphysema caused by genetics

Answer 9

1. Elastase normally inactivated by α-1 antitrypsin. This doesn’t occur if there is a genetic α-1 antitrypsin deficiency.
2. Elastase destroys alveolar walls
3. Emphysema

Question 10

Describe the Mechanism of Asthma.

Answer 10

1. Mast cell activation (irritation, hypersensitivity)
2. Histamine and cytokine released
3. Oedema, mucus, smooth muscle contraction = bronchoconstriction

Question 11

What is a restrictive lung disease?

Answer 11

Reduced compliance = ↓Vital Capacity (VC)

Question 12

Main types of restrictive lung diseases

Answer 12

• Fibrosis - development of excessive connective tissue
  - alveoli replaced by fibrotic tissue = DECREASED lung compliance
• Respiratory distress syndrome (IRDS, ARDS, SARS)

Question 13

What happens is Acute restrictive lung diseases?

Answer 13

Sepsis or severe trauma
= protein exudation
= oedema

Question 14

What happens in Chronic restrictive lung diseases?

Answer 14

Industrial dust, drugs, rheumatism
= inflammation
= fibrosis (development of excess connective tissue)-lungs STIFFER
“Honeycomb lung”

Question 15

What are the 2 types of Respiratory tract infections?

Answer 15

Upper respiratory tract infections
- Common but minor

Lower respiratory tract infections

- Less common but serious
- e.g. bronchitis, pneumonia, tuberculosis...

Question 16

Two Phases of TB.

Answer 16

Latent – asymptomatic, non-infectious, granuloma in lung tissue

Active (~10%) - spreads to bronchioles and circulation

Question 17

What is Ghon focus?

Answer 17

Site of primary infection. where you see alveolar macrophage replication.

Question 18

What happens in the active stage of TB?

Answer 18

• Initial infection – ineffective immune response
• Bacteria moved to lymph nodes
• Collagen deposited around bacteria causing damage to lymph nodes = LYMPH NODES ERRODE
  = bacteria released into circulation
  += bacteria drain into bronchioles so goes around the lung

= alveoli destruction