When things go wrong with the Respiratory System - Lecture 21

Question 1

What are the types of respiratory diseases?

Answer 1

○ Obstructive: conditions which impede the rate of flow into and out of the lungs
○ Restrictive: conditions which cause reduced lung volume
○ Infection and inflammation

Question 2

What is COPD?

Answer 2

○ Chronic obstructive pulmonary diseases
○ Narrowing of airways -> increased airway resistance
○ Increased air volume -> appearance of chest over-inflation

Question 3

What are the main diseases of COPD?

Answer 3

○ Chronic bronchitis - narrowing
○ Emphysema - loss of elastic recoil

Question 4

What is chronic bronchitis and the the two types?

Answer 4

○ Inflammation of the bronchi - mucus hypersecretion
○ Acute bronchitis
○ Chronic bronchitis

Question 5

What is acute bronchitis?

Answer 5

○ Short-lived
○ Due to bacteria/virus
○ Lasts days/weeks

Question 6

What is chronic bronchitis?

Answer 6

○ Due to smoking or environmental irritants
○ Lasts at least 3 consecutive months in 2 consecutive years

Question 7

What are the symptons of chronic bronchitis?

Answer 7

○ Irritants cause inflammation in bronchi
○ Abnormal mucus secretion
○ Plugs airways
○ Prone to infection due to humid environment
○ Further inflammation

Question 8

What is the treatment for chronic bronchitis?

Answer 8

○ Stop smoking
○ Bronchodilators
○ Antibiotics

Question 9

What is are the causes of emphysema?

Answer 9

○ Smoking
○ Genetic α1 antitrypsin deficiency

Question 10

What is the mechanism of emphysema?

Answer 10

○ Neutrophils & macrophages release elastase (normally inactivated by α1 antitrypsin)
○ Elastase destroys alveolar walls

Question 11

What are the symptons of emphysema?

Answer 11

○ Shortness of breath of exertion
○ Hyperventilation
○ Expanded chest

Question 12

What are the treatments for emphysema?

Answer 12

○ Enzyme supplements in α1 antitrypsin deficiency
○ Stop smoking
○ Lung transplant
However loss of alveoli is permanent and irreversible

Question 13

What factors can cause asthma?

Answer 13

○ Hypersensitivity reaction to allergens
○ Air pollution
○ Exercise and cold air
○ Emotional stress
○ Genetics (?)

Question 14

What are the symptoms of asthma?

Answer 14

○ Bronchoconstriction
○ Oedema of airway mucosa
○ Mucus secretion

Question 15

What is the mechanism for asthma?

Answer 15

○ Mast cell activation -> Histamine and cytokine release -> Oedema, mucus, smooth muscle contraction (bronchoconstriction)

Question 16

What are the treatments for asthma?

Answer 16

○ Bronchodilators e.g. Salbutamol (β2 adrenoreceptor agonist)
○ Anti-inflammatories - dampens mast cell activation

Question 17

What causes restrictive lung disease?

Answer 17

Intrinsic or extrinsic to the lung parenchyma

Question 18

What are the causes of intrinsic restrictive lung disease?

Answer 18

○ Long term exposure to dust: pneumoconiosis (asbestosis)
○ Drugs e.g. methotrexate
○ Rheumatoid arthritis
○ ARDS, IRDS

Question 19

What are the causes of extrinsic restrictive lung disease?

Answer 19

Non muscular disease of the upper thorax

Question 20

What is fibrosis?

Answer 20

○ Alveoli replaced by fibrotic tissue
○ Decreased lung compliance
○ Irreversible decrease in oxygen diffustion capacity

Question 21

What are the causes of fibrosis?

Answer 21

○ Inhaled environmental and occupational pollutants
○ Cigarette smoke
○ Autoimmune disease

Question 22

What are the two types of respiratory tract infections?

Answer 22

○ Upper: common but minor
○ Lower: Less common but serious

Question 23

What is pneumonia?

Answer 23

○ Caused by bacteria
○ Affects bronchi & alveoli
○ Inflammatory exudate fills alveoli
○ Leads to ‘consolidation’
○ Lung tissue becomes firm and airless

Question 24

What is the difference between bronchopneumonia and lobar pneumonia?

Answer 24

○ Bronchopneumonia: spread out
○ Lobar pneumonia: within a particular region

Question 25

What is tuberculosis?

Answer 25

○ Caused by inhalation of mycobacterium tuberculosis
○ Latent - asymptomatic, non-infectious, granuloma in lung tissue
○ Active - spreads to bronchioles and circulation

Question 26

What is the mechanism if tuberculosis?

Answer 26

○ Bacteria replicate in alveolar macrophage
○ Ineffective immune response
○ Bacteria move to lymph nodes
○ Collagen deposited around bacteria: breaks down structure of lungs
○ Lymph node erodes which cause bacteria to release and destruction of alveoli

Question 27

How did Covid-19 work?

Answer 27

○ Binding of receptor expressed by host cells (lung epithelial cells)
○ Receptor = angiotensin-converting enzyme 2 receptor (abundant in type 2 alveolar cells)