Asthma is a difficulty in breathing that causes wheezing. It happens because the bronchi and bronchioles (the airways) get inflamed and narrow, and this is triggered by an allergic reaction to allergens like pollen, dust and mites. Memory hook: "Asthma = Airway inflamed" — both start with A, and the block is in the small airways (bronchi/bronchioles), NOT in the alveoli.
In asthma, allergens trigger mast cells in the lungs to inflame the bronchi and bronchioles. The airway wall swells and narrows, so air whistles through as wheezing. Note the block is in the airway, not the alveoli.
Your doubts, answered
Does asthma affect the alveoli or the bronchi and bronchioles?
Asthma affects the bronchi and bronchioles (the airways), NOT the alveoli. NCERT defines asthma as difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles. Damage to alveolar walls (decreased respiratory surface) is emphysema, a different disorder. NEET repeatedly tests this exact swap.
Why does asthma cause wheezing?
When the bronchi and bronchioles get inflamed, their walls swell and the airways narrow. Air is forced through these narrowed tubes, producing a whistling sound called wheezing. So wheezing is the classic sign of the narrowed, inflamed airways in asthma.
What is the difference between the allergen and the cause of asthma?
The allergen (pollen, dust, mites, pet dander, smoke) is the trigger from the environment. The actual cause of the breathing difficulty is the allergic (hypersensitivity) reaction it sets off, which leads to inflammation of the bronchi and bronchioles. In NEET wording, asthma may be 'attributed to' the allergic reaction of mast cells in the lungs — the allergen just starts it.
How are mast cells involved in asthma?
Asthma is an allergic/hypersensitivity condition. Allergens make mast cells in the lungs release chemicals like histamine (and serotonin). These chemicals cause the airways to become inflamed and narrow. That is why NEET 2016 marks 'allergic reaction of the mast cells in the lungs' as the answer for what asthma may be attributed to.
Why are more children in cities getting asthma?
NCERT notes that more and more children in metro cities suffer from allergies and asthma because of increasing air-borne allergens and pollutants. Sensitivity to these environmental particles triggers the exaggerated immune response, so urban air pollution is directly linked to rising asthma cases — this framing appeared in NEET 2019.
⚠️ The NEET trap ✗ Asthma is caused by damage to the alveolar walls / decreased respiratory surface. ✓ Asthma is inflammation of the bronchi and bronchioles (airways). Damaged alveolar walls with decreased respiratory surface is EMPHYSEMA. 🧠 Read the ORGAN, not just the disease name.
Real NEET questions
2016
Asthma may be attributed to:
A · Bacterial infection of the lungs
B · Allergic reaction of the mast cells in the lungs ✓
C · Inflammation of the trachea
D · Accumulation of fluid in the lung
Solution: Asthma is difficulty in breathing with wheezing, caused by inflammation of the bronchi and bronchioles triggered by an allergic (hypersensitivity) reaction of mast cells in the lungs. It is not a bacterial infection, not the trachea (it is the bronchi/bronchioles), and not fluid accumulation.
2019
Due to increasing air-borne allergens and pollutants, many people in urban areas are suffering from respiratory disorder causing wheezing due to
A · benign growth on mucous lining of nasal cavity
B · inflammation of bronchi and bronchioles ✓
C · proliferation of fibrous tissues and damage of the alveolar walls
D · reduction in the secretion of surfactants by pneumocytes
Solution: Wheezing triggered by allergens and pollutants is the classic sign of asthma, which NCERT defines as difficulty in breathing due to inflammation of bronchi and bronchioles. Option (c) describes emphysema/fibrosis and (a) describes nasal polyps.
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 = inflammation of bronchi and bronchioles. Emphysema = alveolar walls damaged, so respiratory surface is decreased. So the correct pairing is asthma → inflammation of bronchioles; emphysema → decreased respiratory surface. Do not reverse the two.
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.
Yes. Asthma is an allergic/hypersensitivity condition. Allergens like pollen, dust and mites trigger mast cells to release histamine, which inflames and narrows the airways.
What is wheezing in asthma?
Wheezing is the whistling sound of air passing through narrowed, inflamed bronchi and bronchioles. It is the classic sign NEET uses to point to asthma.
Does asthma damage the alveoli?
No. Asthma affects the bronchi and bronchioles. Damage to alveolar walls (reduced respiratory surface) is emphysema, which is mainly caused by cigarette smoking.
Which NCERT chapter covers asthma?
Class 11 Biology, Breathing and Exchange of Gases (Ch 14), in the 'Disorders of Respiratory System' section, along with emphysema and occupational disorders.
