Question

practice it
lo 4.4. why is residual volume important?
reflects the amount of oxygen that our body uses during physical activity
measures the amount of air we can forcefully exhale after taking a deep breath
estimates the amount of air we breathe in and out during normal breathing
indicates how much air is needed to fill the lungs completely
shows how much air is left in our lungs to keep them from collapsing

Explanation:

Residual volume is the amount of air remaining in the lungs after maximum exhalation. It helps keep the alveoli (air - sacs in the lungs) open, preventing the lungs from collapsing. The other options:

• "Reflects the amount of oxygen that our body uses during physical activity" is related to oxygen consumption, not residual volume.
• "Measures the amount of air we can forcefully exhale after taking a deep breath" is vital capacity (not residual volume).
• "Estimates the amount of air we breathe in and out during normal breathing" is tidal volume.
• "Indicates how much air is needed to fill the lungs completely" is total lung capacity (sum of all lung volumes including residual volume).

Answer:

Shows how much air is left in our lungs to keep them from collapsing.