Pathophysiology Of Lung Disease

Question 1

What is a respiratory disease?

Answer 1

Respiratory disease is the medical term to describe the pathological conditions affecting organs and tissues that make gas exchange possible. Including:
• the upper respiratory tract
• the trachea
• bronchi
• bronchioles
• alveoli
• pleura
• the pleural cavity
• nerves and respiratory muscles

Question 2

How can lung diseases be classified?

Answer 2

• inflammatory diseases
• obstructive diseases
• respiratory tract infections
• pleural cavity disease
• pulmonary vascular disease
• neonatal disease

Question 3

Give 6 examples of an inflammatory lung disease.

Answer 3

1) asthma
2) cystic fibrosis
3) emphysema
4) chronic obstructive pulmonary disease (COPD)
5) acute respiratory distress syndrome
6) interstitial lung disease

Question 4

What are the two categories of asthma?

Answer 4

1) extrinsic (allergic)

2) intrinsic

Question 5

What are the two categories of asthma and how can the two be identified?

Answer 5

Intrinsic asthma - no sign of atopy (allergic reaction), more common in adults, pathophysiology similar to extrinsic, lung function declines more quickly.

Extrinsic asthma - an immune response (atopy) to an allergen, usually occurs in childhood, accounts for 60% of asthma cases, often a family history, generally improves with age.

Question 6

What are the symptoms of asthma?

Answer 6

• breathlessness, chest tightness, cough, wheeze on expiration
• diurnal variation - often worse at night
• life-threatening asthma is characterised as a peak flow

Question 7

What causes airway inflammation in the pathophysiology of asthma?

Answer 7

• smooth muscle contraction
• thickening of the airway wall
• basement membrane thickening
• mucus and exudate in the airway lumen

Question 8

Explain the process of inflammatory mediators in the pathophysiology of asthma.

Answer 8

1) inflammatory stimuli activate mast cells, epithelial cells, alveolar macrophages and dendritic cells resident within the airways
2) this causes the release of mediators that attract further inflammatory cells to the airway (eosinophils, neutrophils and platelets)
3) there are two patterns of response. Most asthmatics will show both however each can occur without the other:
• immediate reaction - maximal airway narrowing within 10-15 minutes of exposure to challenge, with a return to baseline in 1-2 hours
• late reaction - influx of inflammatory cells and release of inflammatory mediators causing airway narrowing after 3-4 hours that is maximal at 6-12 hours. This is much more difficult to reverse than the immediate reaction.

Question 9

Outline the pathology of asthma.

Answer 9

1) intermittent narrowing of the bronchi, causing cough, wheeze on expiration and shortness of breath
2) muscles in airways contract, causing narrowing
3) airway lining becomes swollen and inflamed
4) production of excess mucus blocks smaller airways

Question 10

What is COPD?

Answer 10

Chronic obstructive pulmonary disease - blanket term for chronic conditions of emphysema and chronic bronchitis. It is a gradually progressive disease of the lungs which involves airways obstruction.

Question 11

List the risk factors associated with COPD.

Answer 11

• smoking
• social deprivation
• diet
• occupational exposure to dust or indoor pollution
• inherited ‘faulty’ genes

Question 12

What is chronic bronchitis?

Answer 12

Chronic bronchitis results from the inflammation and irritation of the airways of the lung. It results in increased mucus production and inflammation which causes airway narrowing. This leads to wheezing and shortness of breath and is characterised by the presence of a cough and phlegm production for more than 3 months in 2 consecutive years.

Question 13

What is emphysema?

Answer 13

Emphysema is the permanent enlargement of the air spaces distal to the terminal bronchioles, leading to destruction of the alveolar walls. Bullae (large air sacs) form which reduces gas transfer due to loss of surface area. Patients are more prone to pneumothorax from bullae rupturing.

Question 14

Briefly outline the pathology of COPD.

Answer 14

1) inhaled irritants cause chronic inflammation of the airways, lung tissue and pulmonary blood vessels
2) irritants cause inflammatory cells (neutrophils, lymphocytes and macrophages) to accumulate
3) these inflammatory cells trigger inflammatory mediators which sustain inflammatory markers, resulting in tissue damage

Question 15

Give 6 examples of upper respiratory tract infections:

Answer 15

1) common cold
2) sinusitis
3) tonsillitis
4) otitis media
5) pharyngitis
6) laryngitis

Question 16

Give 4 examples of lower respiratory tract infections:

Answer 16

Pneumonia:

1) bacterial streptococcus pneumoniae
2) tuberculosis
3) acute respiratory syndrome
4) pneumocystis pneumonia

Question 17

Name 4 types of lung cancer.

Answer 17

1) small cell lung cancer (SCLC)
2) non-small cell lung cancer
3) lymphoma
4) head and neck

Question 18

Name the 3 types of small cell lung cancer.

Answer 18

1) small cell carcinoma
2) mixed small/large cell carcinoma
3) combined small cell carcinoma

Question 19

List the symptoms of small cell lung cancer. [7 symptoms]

Answer 19

1) coughing
2) bloody sputum
3) shortness of breath
4) wheezing
5) chest pain
6) loss of appetite
7) weight loss

Question 20

Name the 3 types of non-small cell lung cancer.

Answer 20

1) squamous cell carcinoma
2) adenocarcinoma
3) large cell carcinoma

Question 21

What causes interstitial lung disease?

Answer 21

• occupational exposure such as asbestos
• medication, drug and radiation exposure
• tobacco exposure
• sarcoidosis
• idiopathic pulmonary fibrosis

Question 22

What is idiopathic pulmonary fibrosis?

Answer 22

A progressive decline in lung function caused by lung tissue scarring and excessive deposition of collagen in the interstitial with minimal inflammation, resulting in increased dyspnoea with no true known cause.

Question 23

Describe the recent findings associated with idiopathic pulmonary fibrosis.

Answer 23

• development of fibroblastic foci precedes accumulation of inflammatory cells and collagen deposition
• production of fibroblasts goes out of control causing scarring and hardening (fibrosis) of delicate lung tissue
• levels of fibrosis increase leading to a gradual decline in lung function and symptoms of IPF

Question 24

What is pleural effusion?

Answer 24

A collection of fluid in the pleural cavity.

Question 25

What causes pleural effusion?

Answer 25

• congestive heart failure
• cirrhosis
• inflammation of pleura

Question 26

What is a pneumothorax?

Answer 26

A hole in the pleura which allows air to escape from the lung into the pleural cavity which causes the lung to collapse.

Question 27

What is a pulmonary embolism?

Answer 27

A blood clot in the vein that travels and lodges in the lung.

Question 28

What is pulmonary arterial hypertension?

Answer 28

Elevated pressure in pulmonary arteries associated with IPD ad COPD.

Question 29

What is pulmonary oedema?

Answer 29

Fluid which leaks from the capillaries into the alveoli, associated with congestive heart failure.

Question 30

What is pulmonary haemorrhage?

Answer 30

Inflammation and damage to capillaries resulting in blood leaking into the alveoli, associated with auto immune disorders.