Residual Volume (RV)
Defines the volume of air remaining in the lungs even after a forceful expiration.
What is Residual Volume (RV)?
The volume of air remaining in the lungs after a maximal exhalation.
Key formula / rule: Functional Residual Capacity (FRC)
Key points
- Define Residual Volume.
- Explain the physiological significance of Residual Volume.
- Differentiate Residual Volume from other lung volumes and capacities.
- Identify factors influencing Residual Volume.
Common exam trap
Confusing RV with Functional Residual Capacity (FRC) or Total Lung Capacity (TLC).
Definitions
- Term
Residual Volume (RV)
- Meaning
The volume of air remaining in the lungs after a maximal exhalation.
- Term
Alveoli
- Meaning
Tiny air sacs in the lungs where gas exchange occurs.
- Term
Spirometry
- Meaning
A pulmonary function test used to measure lung volumes and capacities.
- Term
Functional Residual Capacity (FRC)
- Meaning
The volume of air remaining in the lungs after a normal exhalation.
Learning objectives
Define Residual Volume.
Explain the physiological significance of Residual Volume.
Differentiate Residual Volume from other lung volumes and capacities.
Identify factors influencing Residual Volume.
Formulae
- Name
Functional Residual Capacity (FRC)
- Note
FRC is the volume of air remaining in the lungs after a normal tidal volume expiration.
- Expression
FRC = ERV + RV
- Name
Total Lung Capacity (TLC)
- Note
TLC is the maximum volume of air the lungs can hold.
- Expression
TLC = IRV + TV + ERV + RV
- Name
Vital Capacity (VC)
- Note
VC is the maximum volume of air that can be exhaled after a maximal inhalation.
- Expression
VC = IRV + TV + ERV
Prerequisites
Understanding of lung anatomy (alveoli, airways).
Basic concepts of lung volumes and capacities (tidal volume, inspiratory reserve volume, expiratory reserve volume).
Knowledge of the mechanics of breathing (inhalation and exhalation).
Common mistakes
Confusing RV with Functional Residual Capacity (FRC) or Total Lung Capacity (TLC).
Assuming RV can be measured directly with a standard spirometer.
Underestimating the importance of RV for continuous gas exchange.
Keywords
Residual Volume
Lung Volumes
Respiratory Physiology
Spirometry
Alveolar Patency
Gas Exchange
Pulmonary Function Tests
Practice preview
Which of the following best describes Residual Volume (RV)?…
easy
If a person's Vital Capacity (VC) is 4600 mL and their Expiratory Reserve Volume (ERV) is 1000 mL, what would be their approximate Residual Volume (RV)?…
medium
Which of the following statements about Residual Volume (RV) is INCORRECT?…
medium