Distensibilité

Distensibilité, also known as compliance in English, is a measure of the ability of a hollow organ or structure in the body to expand or change its volume when subjected to an increase in pressure. It is essentially the inverse of stiffness. A highly distensible structure can accommodate a large volume change with only a small increase in pressure, while a stiff structure will experience a significant pressure rise with a small volume increase.

In physiological contexts, distensibilité is a crucial concept for understanding the function of various organs. For example, the lungs have high distensibilité, allowing them to inflate easily during inhalation. The bladder's distensibilité allows it to store significant amounts of urine without a rapid increase in internal pressure. Similarly, blood vessels, particularly veins, exhibit distensibilité, which helps to buffer pressure changes and maintain blood flow.

Quantitatively, distensibilité is defined as the change in volume divided by the change in pressure: Distensibilité = ΔV / ΔP. A higher value indicates greater distensibilité. Factors influencing distensibilité include the material properties of the organ's walls, such as the amount of elastic tissue and smooth muscle, as well as the presence of external forces or constraints. Pathological conditions can alter distensibilité. For instance, in conditions like emphysema, the lungs lose their elastic recoil and become abnormally distensible, leading to air trapping. Conversely, conditions that stiffen organ walls, such as arteriosclerosis in blood vessels, reduce distensibilité.