Question

The volume of the air remaining in the lungs even after a forceful expiration is
A.Tidal volume
B.Residual volume
C.Inspiratory reserve volume
D.Expiratory reserve volume

Answer 1

Hint: There is always some air left or remaining in the lungs as it requires much energy to re-inflate the lung.

Complete step by step answer:
-The normal expiration happens when the diaphragm relaxes, which will push up into the lungs. The air inside the lungs will thus flow out through trachea, larynx, and pharynx, it is expelled out through the nasal and oral cavity.
-During this process of expiration a small amount of air approximately 1000mL is retained in the lung. This volume of air is retained even after a forceful expiration.
- The volume of air retained by the lungs even after a forceful expiration is called residual volume.
-This residual volume will help to keep the alveoli open even after a forceful expiration.
It will allow a continual gas exchange between the breaths.
-The residual air is oxygen depleted, when it is mixed with the newly inhaled air, it helps to improve the gas exchange at the alveoli since the alveoli remains open.

Hence, the correct option is ‘B’.

Additional information:
-Tidal volume: it is the volume of air that moves in or out of the lungs with each respiratory cycle.
-Inspiratory reserve volume (IRV): it is the volume of air that can be forcibly inhaled. It can be also put as the maximum volume of additional air that can be drawn into the lungs.
-Expiratory reserve volume (ERV): It is the maximum volume of air that can be forcibly exhaled from the lungs.

Note:
Another word for something that is remaining is residue. So the volume of air that remains after forceful expiration is the residual volume.