Inspiratory reserve volume

Inspiratory reserve volume (IRV) Maximum additional volume one can in-... 

Define tidal volume, residual volume, expiratory reserve volume, and inspiratory reserve volume... 

Vital capacity Inspiratory reserve volume Tidal volume... 

The air in the lung is divided into four compartments tidal volume—the air exhaled during quiet breathing inspiratory reserve volume—the maximal air inhaled above tidal volume expiratory reserve volume—the maximum air exhaled below tidal volume and residual volume—the air remaining in the lung after maximal exhalation. The sum of all four components is called the total lung capacity. 

The air within the lung at the end of a forced inspiration can be divided into four compartments or lung volumes (Fig. 25-1). The volume of air exhaled during normal quiet breathing is termed tidal volume (Vt). The maximal volume of air inhaled above tidal volume is called the inspiratory reserve volume (IRV), and the maximal air exhaled below tidal volume is called the expiratory reserve volume (ERV). The residual volume (RV) is the amount of air remaining in the lungs after a maximal exhalation. 

FIGURE 25-1. Lung volumes and capacities. ERV = expiratory reserve volume FRC = functional residual capacity IC = inspiratory capacity IRV = inspiratory reserve volume RV = residual volume TLC = total lung capacity VC = vital capacity Vj = tidal volume. 

Inspiratory reserve volume measures the amount of air that can be added to the lungs forcibly after taking a normal breath. Similarly, expiratory reserve is the amount of air that can be expelled forcibly after a normal expiration. Vital capacity = inspiratory reserve volume + expiratory reserve. 

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