Resp Path 1 - Obstructive diseases

Question 1

What is the pulmonary acinus

Answer 1

The are of lung distal to the terminal bronchiole.

Question 2

What is the main epithelium in the lung?

Answer 2

Pseudostratified ciliated columnar with seromucinous glands

Question 3

Define obstructive airways disease?

Answer 3

A limitation in airflow caused by an increase in resistance due to a complete or partial obstruction.

Question 4

Main cause and PFT changes in localised obstruction?

Answer 4

Tumour and no changes in PFTs

Question 5

What is the obstructive pattern of PFTs?

Answer 5

Decreased vital capacity, decreased PEFR and decreased FEV1/VC (=0.7).

Question 6

Which conditions are classified as obstructive airway diseases?

Answer 6

Chronic bronchitis/emphysema - COPD
Asthma
Bronchiectasis

Question 7

What is the definition of chronic bronchitis?

Answer 7

Persisent productive cough for three months of the year for two years and not attributed to other causes.

Question 8

What is the definition of emphysema?

Answer 8

Lung condition characterised by abnormal permanent enlargement of the airspaces of the acinus with destruction of the walls (elastin) and minimal fibrosis.

Question 9

What is meant by blue bloater?

Answer 9

Hypoxic, cyanotic and hypercapnic appearance of chronic bronchitis patients.

Question 10

What is meant by pink puffer?

Answer 10

Over-ventilating patients due to parenchymal loss, usually well ventilated at rest.

Question 11

Main 2 pathological processes in chronic bronchitis?

Answer 11

1. ) Mucous hypersecretion beginning in bronchi and trachea due to hypertrophy of mucous-secreting cells and an increase in mucin-secreting goblet cells in the smaller airway stimulated by inflammatory mediators i.e. histamine and IL-3.
2. ) Inflammation with neutrophil, macrophage and lymphocyte infiltration and accompanying fibrosis.

Question 12

What can occur as a result of chronic bronchitis?

Answer 12

Squamous cell metaplasia/dysplasia/carcinoma.

Question 13

Main pathological processes of emphysema?

Answer 13

1.) Ongoing inflammation with neutrophil, lymphocyte and macrophage infiltration.
2.) Epithelial injury and proteolysis of extracellular matrix caused by cytokines, elastases and oxidants.
3.) Elastin degradation products cause further inflammation.
Cycle continues unless checked by anti-elastases such as alpha 1 antitrypsin.

Question 14

How does the loss of elastic tissue in the alveloi impact on breating?

Answer 14

It reduces radial traction and causes bronchiole collapse during expiration.

Question 15

How does emphysema appear on x-rays/CT scans?

Answer 15

Lung is voluminous

Question 16

What is a major complication of emphysema?

Answer 16

Alveolar wall rupture –> bullae and blebs –> Pneumothorax

Question 17

What are the four classifications of emphysema?

Answer 17

1. ) Centiacinar
2. ) Panacinar
3. ) Distal acinar
4. ) Irregular

Question 18

Describe centriacinar emphysema?

Answer 18

Commonest form, smoking-related, involves destruction of respiratory bronchiole at centre of acinus, upper zones are worse affected.

Question 19

Describe panacinar emphysema?

Answer 19

Ass. w/ alpha 1 antitrypsin deficiency, affects whole acinus, lower zones worst affected.

Question 20

Describe distal acinar emphysema?

Answer 20

Located at the distal edge of the acinus near the pleura, is the underlying lesion in spontaneous pneumothorax.

Question 21

Describe irregular emphysema?

Answer 21

Irregular acinar involvement ass w/ scarring, mainly asymptomatic and of little clinical significance.

Question 22

Define bronchial asthma?

Answer 22

Episodic reversible bronchospasm du to an exaggerated bronchoconstrictor response to stimuli leading to dyspnoea, wheezing and cough.

Question 23

What causes the wheezing in bronchial asthma?

Answer 23

Resistance to airflow in the smaller airways.

Question 24

Classifications of asthma?

Answer 24

1. ) Atopic
2. ) Non-atopic
3. ) Drug-induced
4. ) Occupational.

Question 25

Describe atopic asthma?

Answer 25

Commonest, type 1 IgE hypersensitivty reaction, early childhood and family history, ass w/ eczema +/- hay fever, wheel and flare reaction to skin testing.

Question 26

Describe non-atopic asthma?

Answer 26

No allergen sensitisation, ass w/ recurrent infection and pollutants, virally or chemically induced inflammation reduces threshold for vagal stimulation by other minor irritants.

Question 27

Describe drug-induced asthma?

Answer 27

Aspirin, related to effects on cyclooxygenase pathway.

Question 28

Describe occupational asthma?

Answer 28

Related to fumes, gases, chemicals etc, combo of type I and type III hypersensitivity.

Question 29

Give a detailed account of pathogenesis of bronchial atopic asthma?

Answer 29

1. ) Inhaled allergens elicit type 2 helper T cell response.
2. ) Cytokines favour IgE production and eosinophil recruitment.
3. ) IgE coats submucosal mast cellswhich on re-exposure to the allergen release granule contents.
4. ) Early and late phase reactions are induced.

Question 30

Describe the early phase reaction in bronchial atopic asthma?

Answer 30

Bronchoconstriction due to supepithelial vagal stimulation, increased mucous production and variable vasodilation.

Question 31

Describe the late phase reaction?

Answer 31

Inflammation with eosinophil, netrophils and T cells stimulate a fresh mediator release with epithelial damage.

Question 32

Early and late phase reactions combine to?

Answer 32

Occlude bronchioles with thick mucous plugs –> distal overinflation or atelectasis.

Question 33

Repeated inflammation as a result of bronchial asthma can lead to what pathological processes?

Answer 33

1. ) Bronchial SM hypertrophy
2. ) Increased vascularity
3. ) Subepithelial collagen thickening
4. ) Submucosal gland hypertrophy
5. ) Goblet cell metaplasia.

Question 34

Define bronchiectasis?

Answer 34

Irreversible permanent dilation of bronchi and bronchioles.

Question 35

General pathogenesis of bronchiectasis?

Answer 35

Destruction of muscle and elastic tissue resulting from a chronic necrotising infection leading to bronchial dilation.

Question 36

Aetiology of bronchiectasis?

Answer 36

Severe infection alone, severe infection w/ bronchial obstruction, immunosuppression, CF.

Question 37

Clinical symptoms of bronchiectasis?

Answer 37

Chronic cough, fever, copious amounts of foul-smelling sputum.

Question 38

Histology of bronchiectasis?

Answer 38

Mucosal ulceration, granulation tissue, mucosa, submucosa, cartilage and muscle destruction, loss of cilia, fibrosis, inflammation, squamous metaplasia.

Question 39

Briefly describe CF?

Answer 39

Autosomal recessive condition affecting long arm of chr 7, abnormal NaCl transfer across basolateral membranes –> increased mucous viscosity.