What factors can affect functional residual capacity?
Functional residual capacity (FRC) can be affected by factors such as body position (decreased in supine position), lung and chest wall compliance, respiratory muscle strength, age, obesity, pregnancy, and certain lung diseases like COPD and restrictive lung diseases. Anesthesia and mechanical ventilation can also alter FRC.
How is functional residual capacity measured?
Functional residual capacity (FRC) is measured using techniques such as body plethysmography, helium dilution, or nitrogen washout. Body plethysmography involves sitting in an airtight box and breathing against a closed shutter, while gas dilution methods involve inhaling a known concentration of helium or nitrogen to calculate FRC based on gas exchange.
Why is functional residual capacity important in respiratory physiology?
Functional residual capacity (FRC) is important because it represents the volume of air remaining in the lungs after a normal expiration, providing a buffer to prevent alveolar collapse. It ensures continuous gas exchange, maintains open airways, and optimizes lung compliance, playing a crucial role in efficient respiration.
What is the normal range for functional residual capacity in adults?
The normal range for functional residual capacity (FRC) in adults is approximately 2.5 to 3.5 liters.
How does age impact functional residual capacity?
As age increases, functional residual capacity (FRC) tends to increase slightly due to changes in lung and chest wall compliance. The tissues become less elastic, leading to decreased expiratory reserve volume and increased residual volume, ultimately resulting in a higher FRC. However, this change may also contribute to reduced overall lung function.