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Cheat sheet · NEET Preparation Zoology

Breathing and Exchange of Gases cheat sheet

The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.

NEET · Zoology

Cheat sheet

Class 11 · Chapter 14Breathing and Exchange of Gases

Air path: nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.

1. Mechanism

  • Inspiration: diaphragm contracts, ribs up → volume ↑, pressure ↓.
  • Expiration: muscles relax → volume ↓.

2. Respiratory Volumes

VolumeValue
Tidal volume≈ 500 mL
Inspiratory reserve2500–3000 mL
Expiratory reserve1000–1100 mL
Residual volume1100–1200 mL
Vital capacityERV + TV + IRV
Total lung capacityVC + RV

3. Gas Transport

  • O₂: 97% as oxyhaemoglobin, 3% dissolved.
  • CO₂: 70% as bicarbonate, 20–25% as carbaminohaemoglobin, 7% dissolved.
  • Carbonic anhydrase speeds CO₂ + H₂O ⇌ H₂CO₃.
  • O₂ dissociation curve is sigmoid; shifts right with high CO₂, H⁺, temperature.

4. Disorders

  • Asthma: bronchi inflamed.
  • Emphysema: alveolar walls damaged (smoking).
  • Occupational: fibrosis from dust.

5. Key Points

  • Respiratory rhythm centre: medulla.
  • pO₂ alveoli ≈ 104 mm Hg.
  • Each 100 mL blood delivers ~5 mL O₂ to tissues.
  • Diffusion membrane is very thin.

Remember: Breathing mechanics | volumes | O₂ & CO₂ transport

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