metarteriolákból

Metarterioles are small blood vessels that act as a transition between arterioles and capillaries. They are similar in structure to arterioles but are generally smaller in diameter. The primary function of metarterioles is to regulate blood flow into the capillary beds. They possess smooth muscle in their walls that can constrict or dilate, thereby controlling the amount of blood that enters the network of capillaries. This precise control is crucial for meeting the varying metabolic demands of tissues. When a tissue requires more oxygen and nutrients, the precapillary sphincters, which are located at the junction of metarterioles and true capillaries, relax, allowing more blood to flow through. Conversely, when the tissue's metabolic activity is low, these sphincters constrict, diverting blood away from the capillaries. Metarterioles also play a role in shunting blood. In some cases, they can bypass the capillary network entirely, allowing blood to flow more directly back to venules, particularly during periods of low metabolic demand or in specific physiological situations. The wall of a metarteriole is typically composed of endothelium, a layer of smooth muscle, and an outer layer of connective tissue. Their diameter can range from about 10 to 100 micrometers.