This is a prototypical output of a 'spirometer'. The y-axis signifies the volume, with the bottom left corner equaling 'zero volume'. The sinusoid comes from repeated resting state breathing (small amplitude sinusoid) 'Tidal Volume', one inspiratory segment to maximum volume (large positive spike) 'Total Lung Volume', a forced expiratory segment to the lowest physiologically possible lung volume (large negative spike), 'Residual Volume', and then concludes with another segment of resting state breathing at tidal volume.

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This is a prototypical output of a 'spirometer'. The y-axis signifies the volume, with the bottom left corner equaling 'zero volume'. The sinusoid comes from repeated resting state breathing (small amplitude sinusoid) 'Tidal Volume', one inspiratory segment to maximum volume (large positive spike) 'Total Lung Volume', a forced expiratory segment to the lowest physiologically possible lung volume (large negative spike), 'Residual Volume', and then concludes with another segment of resting state breathing at tidal volume.