When a man inhales air containing normal concentration of \(\mathrm{O}_2\) as well as \(\mathrm{CO}\) he…

When a man inhales air containing normal concentration of \(\mathrm{O}_2\) as well as \(\mathrm{CO}\) he suffers from suffocation because
  1. \(\mathrm{CO}\) reacts with \(\mathrm{O}_2\) reducing its percentage in air
  2. haemoglobin combines with \(\mathrm{CO}\) instead of \(\mathrm{O}_2\) and forms carboxyhaemoglobin
  3. \(\mathrm{CO}\) affects diaphragm and intercostal muscles
  4. \(\mathrm{CO}\) affects the nerves of the lungs.

Solution

Affinity of carbon monoxide for haemoglobin is 200 times more than oxygen. At 0.5 partial pressure, $\mathrm{CO}$ combines with $50 \%$ of haemoglobin. It produces a relatively stable compound called carboxy-haemoglobin. This causes low supply of oxygen to the body which is characterised by headache, dizziness, nausea, etc.

Asked in: NEET 2015 (Phase 1)

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