COPD Chronic Bronchitis

Question 1

Define chronic bronchitis

Answer 1

Hyper secretion of mucus and chronic productive cough for at least three months for at least two consecutive years

Question 2

What is chronic bronchitis characterised by?

Answer 2

Chronic inflammation, execessive mucus production and airflow obstruction

Question 3

Explain the inflammatory response:

Answer 3

Irritants produce a persistent inflammatory response in the bronchial walls. The bronchi becomes infiltrated with immune cells such as neutrophils, macrophages and CD8 + T cells. Immune cells are degranulated and release mediators like cytokines and proteases to the bronchial tissue

Question 4

What immune mediators are released?

Answer 4

Cytokines, elastase, histamine, leukotrienes

Question 5

What does enzyme elastase cause?

Answer 5

Elastase enzyme destructs the elastin in the alveoli and bronchial walls contributing to a loss of recoil, airway remodelling, increased air way resistance and compromised surface area for gas exchange. It also stimulates goblet cell hyperplasia, increasing mucus production causing airflow obstruction + productive cough

Question 6

Explain goblet cell hyperplasia and mucous gland hyper trophy:

Answer 6

Inflammatory mediators such as cytokines and elastase stimulate an increased production of goblet cells in the endothelial lining. Goblet cells then increase in numbers + size (hyperplasia and hyper trophy) secreting more mucus. The submucosal glands also enlarge, further contributing to mucus secretion. The excess mucus obstructs the airflow esp in smaller airways, impairs ciliary clearance and can host bacteria (recurrent infections)

Question 7

Why is there airflow limitation in bronchitis?

Answer 7

Due to inflammation, mucus plugs and narrowed bronchi. Airflow is limited especially in expiration. This leads to air trapping, hyper inflation of the lungs and hypoventilation

Question 8

Explain hypoxia and hypercapnia in bronchitis pathophysiology:

Answer 8

Gas exchange is impaired due to mucous blocking alveoli and reduced alveolar ventilation. This causes low oxygen levels in blood - hypoxaemia leading to hypoxia. High carbon dioxide in blood due to mucus trapping air - hypercapnia.

Question 9

What does chronic hypoxia cause in bronchitis?

Answer 9

Pulmonary vasoconstriction - hypertension is pulmonary arteries. This eventually strains the right side of the heart causing cor-pulmonale

Question 10

Signs and symptoms of chronic bronchitis:

Answer 10

Repeated chest infections, productive cough, dyspnoea, wheezing, chest pain, fatigue