From which lung volumes does the increased TV come from during exercise?
The correct answer and explanation is:
During exercise, the increased tidal volume (TV) primarily comes from two lung volumes: the expiratory reserve volume (ERV) and the inspiratory reserve volume (IRV). Tidal volume refers to the amount of air moved in and out of the lungs with each breath. During exercise, the body requires more oxygen and needs to expel more carbon dioxide, which increases the depth of breathing (tidal volume).
Increased tidal volume during exercise results from the body’s demand for higher ventilation to meet the metabolic needs of muscles. Normally, tidal volume is quite small during rest, but as exercise intensity increases, the body compensates by drawing more air in and expelling more during each breath. This is facilitated by the reduction in expiratory reserve volume (ERV) and the inspiratory reserve volume (IRV).
- Expiratory Reserve Volume (ERV): This is the volume of air that can be exhaled forcefully after a normal exhalation. During exercise, the body utilizes more of this volume as it increases the rate of exhalation and expiration depth to expel carbon dioxide.
- Inspiratory Reserve Volume (IRV): This is the maximum amount of air that can be inhaled after a normal inhalation. During exercise, the body draws more air into the lungs, extending the inspiratory phase of each breath to meet increased oxygen needs.
Together, these volumes are utilized during exercise to increase tidal volume. The total ventilation increases significantly because both the depth (tidal volume) and frequency (rate of breathing) of breaths increase. The combination allows the lungs to effectively meet the demands of the body during physical activity.