Utandningen

Utandningen (Swedish for "the exhalation") refers to the outward phase of the respiratory cycle in which air is expelled from the lungs. It is one half of normal ventilation, paired with inhalation, and serves to remove carbon dioxide produced by cellular metabolism while helping to maintain acid–base balance in the body.

During quiet breathing, exhalation is largely passive: the diaphragm and external intercostal muscles relax, and the elastic recoil of the lungs and chest wall drives air out. Forced or active exhalation—required during exercise, coughing, singing or speech—involves contraction of expiratory muscles, chiefly the internal intercostals and abdominal muscles, to increase intrathoracic pressure and expedite air flow.

Physiological control of exhalation is coordinated by respiratory centers in the brainstem, which integrate input from central and peripheral chemoreceptors that monitor CO2, pH and O2 levels, as well as from mechanoreceptors in the lungs. Alterations in the mechanics or control of exhalation are central to many respiratory conditions: obstructive diseases such as asthma and chronic obstructive pulmonary disease impede airflow out of the lungs, while neuromuscular disorders can weaken expiratory muscles.

Exhalation can be assessed clinically by spirometry and peak expiratory flow measurements. Therapeutic and self-care techniques—pursed-lip breathing, diaphragmatic breathing and controlled breathing exercises—are used to improve ventilation efficiency, relieve dyspnea and support rehabilitation in chronic respiratory disease. The term is also used metaphorically in literature and popular culture to evoke relief, release or finality.