Expiratory reserve volume

Expiratory reserve volume (ERV) Maximum additional volume one can... 

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

Expiratory reserve volume Maximum volume of gas that can be expired below FRC level... 

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. 

The residual volume (RV) is calculated by subtracting the expiratory reserve volume (measured directly with the spirometer) from the FRC. 

Deposition in the thoracic region is the sum of aerodynamic and thermodynamic deposition of particulate material. Aerodynamic deposition depends on aerodynamic particle size, total volumetric flow rate, anatomical dead space, tidal volume, functional residual capacity (FRC) (combined residual and expiratory reserve volume or the amount of air remaining in the lungs after a tidal expiration) and diameter of the airways. Thermodynamic deposition depends on anatomical and physical characteristics, such as tidal volume, anatomical dead space, functional residual capacity and the transit time of air within each region. Thermodynamic particle size, which is derived from the diffusion coefficient, particle shape factor and the particles mass density, influence thermodynamic deposition. 

Anumber of respiratory adjustments are made to reduce energy expenditure during exercise respiration rate increases, the ratio of inhalation time to exhalation time decreases, respiratory flow waveshapes become more trapezoidal, and expiratory reserve volume decreases. Other adjustments to reduce energy expenditure have been theorized but not proven (Johnson, 1991]. 

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