Question

State the volume of air remaining in the lungs after a normal breathing.

Answer 1

Respiratory volumes are the quantity of air that can be sustained in our lungs or expelled in a number of other conditions. The volume of air remaining in the lungs after normal breathing is called the Functional Residual Capacity (FRC).

Complete answer:
- Functional Residual Capacity is the sum of two other respiratory volumes namely, Expiratory Reserve Volume (ERV) and Residual Volume (RV).
- Expiratory Reserve Volume (ERV) is the additional or extra volume of air a person can expire after a forceful expiration. This volume ranges from 1000 mL to 1100 mL.
- Residual volume (RV) is the volume of air that remains in the lungs even after the forceful expiration. It is about 1100 mL to 1200 mL.
- Thus, Functional Residual Capacity ranges from 1800 mL to 2200 mL.

Additional information:
Other respiratory capacities include:
• Inspiratory Capacity (IC): It is the amount of air a person can inspire after a normal expiration. Tidal volume and inspiratory reserve volume (TV+IRV) makeup the Inspiratory Capacity.
• Expiratory Capacity (EC): The amount of air a person can expire after a normal inspiration (TV+ERV) is called the Expiratory Capacity.
• Vital Capacity (VC): It is the maximum amount of air a person can breathe in after a forceful expiration and the total amount of air a person can breathe out after a forceful inspiration (ERV+TV+IRV or IC+ERV).
• Total Lung Capacity (TLC): It is defined as the total volume of air present in the lungs and the respiratory passage after a maximum inspiration (RV+ERV+TV+IRV or IC+FRC).

Note: Other respiratory volumes include:
• Tidal volume (TV): During normal breathing, the amount of air inspired or expired is referred to as tidal volume.
• Inspiratory Reserve Volume (IRV): It is the extra or additional volume of air a person can inspire by a forceful inspiration. This volume ranges from 2500 mL to 3000 mL.