Respiratory Disorders

Respiratory disorders occur when air cannot move properly, gas exchange surface gets damaged, or lungs become fibrosed (stiff). NCERT mainly highlights:

  • Asthma (airway narrowing)
  • Emphysema (alveoli destruction)
  • Occupational respiratory disorders like silicosis and asbestosis (fibrosis due to dust)

Important Points:

  • Asthma = problem in airways (bronchi/bronchioles)
  • Emphysema = problem in alveoli (surface area decreases)
  • Occupational diseases = problem in lung tissue (fibrosis → stiff lungs)

Asthma

What exactly happens?

Asthma is a chronic inflammatory disorder of the airways in which:

  • Bronchioles undergo smooth muscle spasm (bronchoconstriction)
  • Mucus secretion increases
  • Airway lining becomes swollen (inflammation/edema)

Result: Air passage becomes narrow → difficulty in breathing + wheezing

Why wheezing occurs?

When air is forced through narrow tubes, it produces a whistling sound (wheeze), especially during expiration.

Common triggers

  • Allergens: dust, pollen, mites
  • Cold air, smoke, strong smells
  • Sometimes exercise/stress can trigger (general concept)

Key points:

  • Asthma = Inflammation + Bronchoconstriction + Mucus
  • Main effect = Narrow bronchioles → wheeze + breathlessness

Emphysema

What exactly happens?

Emphysema is a type of COPD where:

  • Alveolar walls are destroyed
  • Small alveoli may merge into larger air spaces
  • Effective surface area for diffusion decreases
  • Elastic recoil of lungs decreases → air trapping (hard to exhale fully)

Result: Breathlessness because less oxygen can enter blood efficiently.

Why is smoking strongly linked?

Cigarette smoke contains chemicals that:

  • damage alveolar walls
  • promote chronic inflammation
  • reduce elasticity of lungs

Key points:

  • Emphysema = Alveoli destroyed
  • Main effect = Surface area ↓ → gas exchange ↓
  • Major cause = Smoking

Occupational Respiratory Disorders

What exactly happens?

Long-term inhalation of industrial dust particles causes:

  • Chronic irritation and inflammation
  • Fibrosis (scar tissue formation)
  • Lungs become stiff, diffusion becomes difficult

Examples

  • Silicosis: due to silica dust (mines, stone cutting)
  • Asbestosis: due to asbestos fibres (construction/insulation)

Why are these often irreversible?

Because fibrosis = permanent scarring. Scar tissue does not return to normal lung tissue.

Key points:

  • Occupational disorders = Prolonged dust exposure
  • Main effect = Fibrosis → stiff lungs → poor diffusion

Effects of pollutants

Pollutants can:

  • cause inflammation
  • reduce diffusion efficiency
  • worsen asthma / increase COPD risk

Notes

All these disorders reduce oxygen supply to tissues by either:

  • blocking airways (asthma)
  • destroying exchange surface (emphysema)
  • scarring lungs (occupational diseases)

Respiratory Disorders

ASTHMA = Airways narrow Inflammation + mucus + bronchoconstriction → wheeze

EMPHYSEMA = Alveoli destroyed Surface area ↓ + elastic recoil ↓ → breathlessness (Strongly linked to smoking)

OCCUPATIONAL = Fibrosis (scar) Silicosis (silica) / Asbestosis (asbestos) Fibrosis = irreversible

One-line trick: A-A-A: Asthma = Airway, Emphysema = Alveoli, Occupational = (scarred) Architecture of lung.

💡 Questions and Answers

Q1. Why does asthma cause wheezing?

A1: In asthma, the bronchioles become narrow because of swelling, mucus, and muscle spasm. When air passes through these narrow airways, it makes a whistling sound, which we call wheezing.

Key points:

  • Bronchioles narrow
  • Airflow becomes difficult
  • Wheezing = sound of air through narrow tubes

Q2. Why is emphysema associated with smoking?

A2: Smoking damages the alveolar walls. When these walls break, the surface area for gas exchange reduces and the lungs lose elasticity, so a person feels breathless.

Key points:

  • Smoking → alveoli damage
  • Surface area ↓
  • Breathlessness

Q3. Why are occupational lung diseases often irreversible?

A3: These diseases cause fibrosis, which means permanent scar tissue forms in the lungs. Scar tissue cannot work like normal lung tissue, so the damage usually cannot be reversed.

Key points:

  • Cause = long-term dust exposure
  • Effect = fibrosis (scarring)
  • Fibrosis = permanent / irreversible