COPD: emphysema and chronic bronchitis
How smoke and inflammation destroy alveolar walls (emphysema) and inflame mucus-filled airways (chronic bronchitis), why airways collapse on breathing out, and how gas exchange and the right heart suffer.
By the end, you can
- Explain how elastic recoil and radial traction keep small airways open in the normal lung.
- Describe the protease–antiprotease imbalance and the role of alpha-1 antitrypsin.
- Distinguish emphysema from chronic bronchitis by structure, mechanism and findings.
- Relate loss of recoil and airway collapse to air trapping, hyperinflation and breathlessness.
- Explain how hypoxaemia, hypercapnia and pulmonary hypertension develop in advanced disease.
- Recognise the classic patterns of emphysema, the GOLD grades and the tests of COPD, and explain how each main treatment acts on its mechanism.
What it is
Chronic obstructive pulmonary disease (COPD) is persistent, usually progressive airflow limitation caused by long-term exposure to noxious particles or gases, above all tobacco smoke. It combines, in varying proportions, emphysema (destruction of alveolar walls) and chronic bronchitis and small-airway disease (mucus hypersecretion and narrowed airways).
2 types to tell apart
- Emphysema
- Permanent enlargement of airspaces beyond the terminal bronchioles with destruction of their walls: centriacinar in smokers (upper zones), panacinar in alpha-1 antitrypsin deficiency (lower zones).
- Chronic bronchitis
- A clinical definition: productive cough on most days for at least three months in each of two consecutive years, from mucus hypersecretion and inflamed airways.
Normal function
Elastic lungs and tethered airways
Each alveolar wall is a thin sheet of capillaries and connective tissue rich in elastin. Stretched on inspiration, the store energy like a spring; their elastic recoil, with surface tension, pushes air out during quiet expiration without muscle work.
The same walls hold the small airways open. Bronchioles under about 2 mm across have no cartilage; alveolar walls attached around them pull outwards (radial traction), like guy ropes on a tent, so they stay open as the lung empties.
The is a fine sponge of small alveoli with a vast surface for gas exchange, roughly 50–100 m² in an adult.
Underlying change · Step 1 of 5
Smoke, inflammation and the protease balance
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Underlying change · Step 2 of 5
Emphysema: alveolar walls are destroyed
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Underlying change · Step 3 of 5
Chronic bronchitis: mucus and narrowed small airways
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 4 of 5
Why air is trapped on breathing out
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 5 of 5
Gas exchange, the right heart and exacerbations
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .