| functional residual air | The volume of air remaining in the lungs at the end of a normal, quiet expiration. It is the sum of the residual volume and the expiratory reserve volume. Common abbreviation is frc. (12 Dec 1998) |
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| functional residual capacity | The volume of air remaining in the lungs at the end of a normal, quiet expiration. It is the sum of the residual volume and the expiratory reserve volume. Common abbreviation is frc. (12 Dec 1998) |