Tidal volume: It is the amount of air that moves in or out of the lungs with each respiratory cycle. It measures around 500 mL in an average healthy adult male and approximately 400 mL in a healthy female. It is a vital clinical parameter that allows for proper ventilation to take place.

When a person breathes in, oxygen from the surrounding atmosphere enters the lungs. It then diffuses across the alveolar-capillary interface to reach arterial blood. At the same time, carbon dioxide continuously forms as long as metabolism takes place. Expiration occurs to expel carbon dioxide and prevent it from accumulating in the body. The volume of inspired and expired air that helps keep oxygen and carbon dioxide levels stable in the blood is what physiology refers to as tidal volume.

Organ Systems Involved in Tidal volume

The lungs are responsible for delivering a tidal volume capable of maintaining adequate ventilation. However, producing precise tidal volumes relies on complex coordination between the respiratory center in the brain and the muscles of respiration. The respiratory pacemaker in the brainstem determines the rate and depth at which breathing occurs.

In response to changes in blood oxygen and carbon dioxide levels, central and peripheral chemoreceptors send information to the brainstem to modulate the pacemaker’s firing rate and pattern. The diaphragm, and other inspiratory muscles, respond by altering tidal volume and respiratory rate. The aim is to maintain adequate levels of oxygen and carbon dioxide in the blood. During exercise, for example, oxygen consumption increases, and carbon dioxide accumulates. As a result, respiratory rate and tidal volume rise to meet the increasing demand.

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By Team Learning Mantras