Question

The amount of volume air that can be respired/expired normally is called
(a) Tidal volume
(b) Vital capacity
(c) Residual capacity
(d) Normal volume

Answer 1

Hint: The process of respiration involves inspiration and expiration that involves the intake of oxygen and removal of carbon dioxide from the body. This process results in the expansion and relaxation of the thoracic cavity of the chest.

Complete answer:
During the respiratory cycle, the amount of air that can be inhaled or exhaled and the function of the respiratory center’s respiratory muscles, and the mechanics of the lungs and chest walls are depicted by the process of Tidal volume (TV). In this process, only a normal amount of air is inhaled and exhaled without applying any extra pressure during the process of respiration.
-Respiration in man involves two different processes, inhalation (the process of taking the atmospheric air) and exhalation (the process of releasing the air).
-The total lung capacity (TLC) is during the forced inspiration the total volume of air accommodated in the lungs.
-The vital capacity along with the residual volume together constitute the total lung capacity.
-Vital capacity is the total exchange of air in the body without any external pressure.
-Residual Volume(RV) - It is the amount of air that remains in the lungs after the process of maximum exhalation. 1200ml(20‐25 ml/kg) is the normal adult value and indirectly measured from the summation of FRC and ERV.
-Tidal volume (VT or TV) is defined as the lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied.
How to calculate the Tidal Volume Respiratory rate?
Minute ventilation is the tidal volume times the respiratory rate, in general,
 500 mL × 12 breaths/min = 6000 mL/min.

So, the correct answer is ‘Tidal volume’.

Note:
The lung capacities of an individual varies from species to species depending upon their sizes and their mode of survival and activities they undergo. Thus, the cheetah is said to have the highest lung capacity as it utilizes more energy for increasing its speed while running than humans while on the other hand elephants also have higher lung capacity due to their large size. In the case of human lungs, it can store around 6 liters of air maximum.