And how to know if you need one! While it gets lost easily in the noise of the WIC, the truth is that the wedding is the ceremony, and the reception is the party that happens after the wedding. In a similar way, the rehearsal dinner has become a big deal in the American Wedding Machine, and the rehearsal itself is often an afterthought.
Residual volume (RV) is a lung volume representing the amount of air left in the lungs after a forced exhalation; this volume cannot be measured, only calculated.
Between breaths, when the lungs are at rest, the volume of air in the lungs is called the functional residual capacity (FRC). No air is moving into or out of the lungs during this time. Air flow results from the muscles of respiration creating pressure gradients by changing the volume of the lungs.