inhales

Inhales refers to the act of drawing air into the lungs, the first phase of respiration. In everyday language the verb inhale is used for this action, while in physiology the term inhalation or inspiration describes the process. Inhalation is typically followed by exhalation, the expulsion of air.

During inhalation, the diaphragm contracts and moves downward while the intercostal muscles lift the rib cage, enlarging the thoracic volume. This expansion lowers intrapulmonary pressure below atmospheric pressure, causing air to flow through the airways and fill the lungs. Inhalation is passive during quiet breathing but can be active during exertion, speech, or coughing.

There are different forms of inhalation: quiet tidal inhalation, deep or forced inspiration, nasal inhalation through the nose or oral inhalation through the mouth, and rapid inhalations used in sniffing or certain breathing techniques. Airway resistance and lung compliance influence the effort and volume of air that can be inhaled.

In medicine, inhalation is used to deliver drugs directly to the lungs via inhalers, nebulizers, or other devices. Proper technique affects dose delivery and therapeutic effectiveness. Pulmonary function tests may assess inspiratory capacity and peak inspiratory flow to evaluate respiratory function.

Environmental exposures during inhalation—such as smoke, pollutants, or chemical vapors—pose health risks. Oxygen therapy and anesthetic gases are administered via controlled inhalation under medical supervision.