Respiratory System Question Paper

Descriptive Questions & Answers

1. Explain the differences between aerobic respiration and anaerobic respiration in humans.

   • Answer:
     • Aerobic Respiration: Takes place in the presence of oxygen; completely oxidizes glucose into carbon dioxide and water; releases a large amount of energy (36 or 38 ATP per glucose molecule); occurs in both cytoplasm and mitochondria.
     • Anaerobic Respiration: Takes place in the absence/scarcity of oxygen (in muscle cells); partially breaks down glucose into lactic acid; releases a very small amount of energy (2 ATP per glucose molecule); occurs only in the cytoplasm.

2. State the role of the diaphragm and external intercostal muscles during the process of inspiration (breathing in).

   • Answer: During inspiration:
     • The diaphragm contracts and flattens (moves downwards), increasing the vertical volume of the thoracic cavity.
     • The external intercostal muscles contract, pulling the rib cage upwards and outwards, increasing the horizontal and lateral volume of the thoracic cavity.
     • This combined increase in thoracic volume decreases the air pressure inside the lungs, drawing atmospheric air into the lungs.

3. Define and give the normal values for the following respiratory volumes in humans:

   • (a) Tidal Volume (TV)
   • (b) Vital Capacity (VC)
   • (c) Residual Volume (RV)
   • Answer:
     • (a) Tidal Volume (TV): The volume of air inspired or expired during a normal, quiet breath. Normal value: ~500 mL.
     • (b) Vital Capacity (VC): The maximum volume of air that can be forcibly exhaled after a maximal inspiration. Normal value: ~4500 mL. (VC = TV + IRV + ERV).
     • (c) Residual Volume (RV): The volume of air remaining in the lungs even after a maximal forced exhalation. Normal value: ~1200 mL.

4. Differentiate between Asphyxiation and Hypoxia.

   • Answer:
     • Asphyxiation: A condition characterized by extreme oxygen deficiency in blood and tissues caused by physical interference with breathing (e.g., choking, drowning, toxic gas inhalation).
     • Hypoxia: A general clinical state where tissues are deprived of adequate oxygen supply, which can occur due to various reasons like high altitude (hypoxemic), anemia (anemic), reduced blood flow (stagnant), or cellular poisoning (histotoxic).