Emphysema: Cause, Effect on Alveoli and Link to Smoking
Biology · Breathing and Exchange of Gases · NEET
Emphysema is a chronic respiratory disorder in which the alveolar walls are damaged. Because of this damage, the respiratory (gas exchange) surface of the lungs decreases, so less oxygen can enter the blood. Its main cause is cigarette smoking. Memory hook: "Emphysema Empties the alveoli" — the tiny air sacs break down, so the surface for gas exchange is lost.
In a healthy lung, many small alveoli give a large surface for gas exchange. In emphysema, cigarette smoking damages the alveolar walls, so the sacs merge into fewer large spaces and the respiratory surface decreases.
Your doubts, answered
Is emphysema caused by smoking or by allergens?
Emphysema is caused mainly by cigarette smoking. Allergens (like pollen or dust) trigger asthma, not emphysema. NCERT clearly states that one of the major causes of emphysema is cigarette smoking. So in NEET, if the disorder is linked to smoking, the answer is emphysema.
What is actually damaged in emphysema, the bronchioles or the alveoli?
The alveolar walls are damaged in emphysema. The alveoli are the tiny air sacs where gas exchange happens. This is different from asthma, where the bronchi and bronchioles get inflamed. So emphysema = alveoli damage, asthma = bronchiole inflammation.
Does emphysema increase or decrease the respiratory surface?
It decreases the respiratory surface. When alveolar walls break down, many small alveoli merge into fewer, larger air spaces. Less total wall area means less surface for gas exchange, so less oxygen reaches the blood. NEET often tests this exact wording: 'decreased respiratory surface'.
Why does emphysema cause difficulty in breathing?
Because the surface available for gas exchange is reduced, the lungs cannot take in enough oxygen or remove enough carbon dioxide. This makes each breath less effective, so the person feels breathless, especially during effort.
⚠️ The NEET trap ✗ Emphysema is caused by inflammation of the bronchi and bronchioles. ✓ Emphysema damages the alveolar walls and decreases respiratory surface; inflammation of bronchi and bronchioles is asthma. 🧠 Alveoli = emphysema, Bronchioles = asthma. NTA swaps these two lines to trick you — read which structure is named.
Real NEET questions
NEET 2016
Name the chronic respiratory disorder caused mainly by cigarette smoking:
A · Emphysema ✓
B · Asthma
C · Respiratory acidosis
D · Respiratory alkalosis
Solution: Emphysema is a chronic disorder in which the alveolar walls are damaged, reducing the respiratory surface. NCERT names cigarette smoking as one of its major causes. Asthma is due to inflammation of bronchi and bronchioles, while respiratory acidosis and alkalosis are pH disturbances, not smoking-induced disorders.
NEET 2018
Which of the following options correctly represents the lung conditions in asthma and emphysema, respectively?
A · Increased respiratory surface; Inflammation of bronchioles
B · Increased number of bronchioles; Increased respiratory surface
C · Inflammation of bronchioles; Decreased respiratory surface ✓
D · Decreased respiratory surface; Inflammation of bronchioles
Solution: Asthma is difficulty in breathing due to inflammation of bronchi and bronchioles. Emphysema damages alveolar walls, so the respiratory surface is decreased. Hence asthma = inflammation of bronchioles and emphysema = decreased respiratory surface.
Solved Breathing and Exchange of Gases NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Emphysema is a chronic respiratory disorder in which alveolar walls are damaged, decreasing the respiratory surface, and its main cause is cigarette smoking.
What is the main cause of emphysema?
Cigarette smoking is the main cause of emphysema according to NCERT.
How does emphysema affect the alveoli?
It damages and breaks down the alveolar walls, so the total surface area for gas exchange decreases and less oxygen enters the blood.
How is emphysema different from asthma?
Emphysema damages alveolar walls and decreases respiratory surface; asthma is caused by inflammation of the bronchi and bronchioles. Emphysema is linked to smoking, asthma to allergens.
Which human protein is used to treat emphysema?
The human protein alpha-1-antitrypsin, produced by transgenic animals, is used to treat emphysema. This point appears in the Biotechnology chapter and is sometimes tested in NEET.
