NCERT Solutions for Class 11 Biology Chapter 14 Breathing and Exchange of Gases
NCERT Solutions for Class 11 Biology Chapter 14 Breathing and Exchange of Gases covers the human respiratory system, the mechanism of breathing, exchange and transport of gases, and regulation of respiration.
Overview of Topics & Subtopics (Click to Jump)
1. Respiratory Organs and Mechanism of Breathing
Short Note:
• The human respiratory system includes the nostrils, nasal passage, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli within the lungs.
• Breathing (pulmonary ventilation) involves inspiration (diaphragm contracts and moves down, ribs move up and out, increasing thoracic volume, decreasing pressure, air rushes in) and expiration (reverse process).
2. Exchange of Gases
Short Note:
• Exchange of O2 and CO2 occurs by simple diffusion, mainly determined by pressure/concentration gradients, solubility of gases, and the thickness of the alveolar membrane, occurring at the alveoli (with blood) and at tissues (with blood).
3. Transport of Gases
Short Note:
• About 97% of O2 is transported by haemoglobin as oxyhaemoglobin; the rest (~3%) is dissolved in plasma.
• CO2 is transported mainly (~70%) as bicarbonate ions (HCO3−), about 20-25% bound to haemoglobin as carbamino-haemoglobin, and about 7% dissolved in plasma.
4. Regulation of Respiration
Short Note:
• Respiration is regulated by a respiratory rhythm centre in the medulla of the brain, and a pneumotaxic centre in the pons, which fine-tunes the rate; chemosensitive areas respond to CO2 and H+ concentration to adjust breathing rate.
NCERT Textbook Exercise Questions
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