Exspirations

Exspirations are the air expelled from the lungs during the expiratory phase of respiration. The word is derived from Latin exspirare, meaning to breathe out. In modern physiology, the event is normally referred to as expiration, while exspirations is encountered in older texts or specialized vocabularies as the plural form describing individual exhalations.

During quiet, resting breathing (eupnea), expiration is largely a passive process, driven by the elastic recoil of the lungs and chest wall. When the body requires more oxygen or during exertion, expiratory muscles—primarily the abdominal muscles and the internal intercostals—can actively squeeze air out of the lungs, increasing the rate and force of exhalation. The expelled air carries carbon dioxide from the bloodstream to the atmosphere, helping regulate blood pH and gas exchange.

Lung function is often assessed using expiratory maneuvers. Spirometry measures expiratory volumes and flow rates, including tidal volume, expiratory reserve volume, and forced expiratory volumes such as FEV1 and FVC. These measures support diagnosis and monitoring of conditions like obstructive diseases (for example, asthma and COPD), which tend to reduce expiratory flow and leave air trapped in the lungs, and restrictive diseases, which lower overall lung volumes.

In practice, exspiration is a component of the broader respira­tory cycle, and the terms expiration and exhalation are commonly used interchangeably in modern clinical writing. Exspirations may appear in historical or lexical discussions as a plural form referring to individual exhalations.