1. Define vital capacity. What is its significance?
Solution:
Vital capacity can be defined as the maximum volume of air a person can breathe in post a forced expiration.
Significance of vital capacity:
(i) It depicts the maximum amount of air that can be converted or renewed in the respiratory system in a single respiration
(ii) The excess quantity of inhaled air represents the maximum amount of oxygen available for glucose-oxidation. This way more energy is available for the body.
2. State the volume of air remaining in the lungs after a normal breathing.
Solution:
It can be stated by the functional residual capacity (FRC). FRC is the volume of air that remains in the lungs after a normal expiration. The functional residual capacity is both the expiratory reserve volume (ERV) and residual volume (RV).
The expiratory reserve volume is the maximum volume of air which can be exhaled post a normal expiration which is approximately1000ml-1500ml. The residual volume is the volume of air that remains in the lungs after maximum expiration which is about 1100ml to 1500ml.
Hence,
FRC = ERV + RV
≅ 1500 + 1500 = 3000 ml
Thus, the functional residual capacity of the lungs in human beings is nearly 2500 ml to 3000 ml
3. Diffusion of gases occurs in the alveolar region only and not in the other parts of
respiratory system. Why?
Solution:
Alveoli are the small air sacs of the lungs that allow rapid gas exchange. These structures are specially built for the gas exchange process. The thickness of the alveolar membrane in total is lesser than a millimeter, while the outer surface of the alveolar membrane is in close proximity with the linkage of blood capillaries.
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