Kapillärrekrytering

Kapillärrekrytering refers to the process by which previously non-perfused capillaries become perfused with blood. This phenomenon is particularly important in physiological responses that require increased blood flow to specific tissues, such as during exercise or in response to inflammation.

In a resting state, not all capillaries in a tissue are actively carrying blood. This is a mechanism to conserve blood volume and pressure, and to ensure that blood is preferentially directed to organs with higher metabolic demands. During increased metabolic activity, local factors such as a decrease in oxygen tension, an increase in carbon dioxide, or the release of vasodilator substances like adenosine or nitric oxide, signal the surrounding arterioles to dilate. This dilation reduces resistance to blood flow, allowing blood to enter capillaries that were previously closed off or minimally perfused.

The recruitment of these additional capillaries increases the total surface area available for the exchange of oxygen, nutrients, and waste products between the blood and the tissues. This enhanced exchange capacity is crucial for meeting the elevated metabolic demands of the active tissue. For example, during exercise, kapillärrekrytering in skeletal muscles ensures that sufficient oxygen and glucose are delivered to fuel muscle contraction and that metabolic byproducts are efficiently removed.

The extent and speed of kapillärrekrytering can vary depending on the physiological stimulus and the specific tissue. It is a dynamic process that helps to precisely match blood supply to tissue demand.