Lung Volume and Capacity (Simplified), Study notes of Physiology

Download Lung Volume and Capacity (Simplified) and more Study notes Physiology in PDF only on Docsity!

Lung volume or respiratory volume : It refers to the volume of gas in the lungs at a given time during the respiratory cycle. Spirometry, is a commonly used technique in the clinic to record the amount of air a person can inhale and exhale. In Spirogram, small waves - shows changes in lung volume during normal breathing, forced breathing - large wave. Inspiratory reserve volume (IRV), Tidal volume (TV), Expiratory reserve volume (ERV), and Residual volume (RV) are the four types of lung volumes. Tidal Volume (TV) : Tidal volume is the amount of air inhaled and exhaled during a normal, resting breath.

The Expiratory reserve volume (ERV) is the maximum amount of air that can be exhaled forcefully after a normal tidal expiration. It indicates how much extra air can be pushed out of the lungs beyond a regular exhalation. Residual volume (RV) - The air remaining in the lungs after a full exhalation. Total lung capacity (TLC) , which is the sum of all lung volumes (TV + IRV + ERV

• RV) and represents the total volume of air the lungs can hold. These additional measurements provide a complete assessment of lung function and are particularly useful in diagnosing restrictive or obstructive lung diseases.

There are four types of lung capacities : Total lung capacity, Vital capacity, Inspiratory and functional residual capacity. Vital capacity tests the maximum limits of the lung, the total amount of gas that a human can inhale after a forced exhalation, and vice-versa. Vital capacity also indicates the health of the lung. Imbalance in this capacity means the lung is not in proper health. Lack of vital capacity indicates congested lungs, where the diaphragm doesn’t move correctly, or our lungs don’t expand fully. Vital capacity = Tidal volume (TV) + Expiratory reserve volume (ERV) + Inspiratory reserve volume.