Venulák

Venulák is a term used in some Slavic-language medical texts to refer to a small venule, the vessel that drains blood from capillary networks. It is a diminutive form derived from venula and is encountered in descriptions of the microcirculation.

Anatomy and physiology: Venuláky are short, thin-walled vessels that link capillaries to larger venules and veins. Their walls are composed mainly of a single endothelial layer, with a sparse or absent tunica media; pericytes may enwrap portions of the wall in some tissues. This structural simplicity contributes to higher permeability compared with larger vessels and facilitates leukocyte migration during inflammatory responses.

Function: The primary role is to collect blood from capillary beds and transport it toward the venous system. They participate in exchange processes in the postcapillary segment and contribute to regulation of microcirculatory resistance and fluid movement; during inflammation they may dilate and permit leukocyte extravasation.

Distribution and clinical relevance: Venuláky are found throughout the vascular network in most tissues, with higher densities in mucosal surfaces and the skin. Pathologically, venular dilation or increased permeability can contribute to edema and microvascular dysfunction in conditions such as inflammatory diseases, sepsis, and ischemia-reperfusion injury. Imaging and histology can distinguish venules from arterioles by lack of smooth muscle in the wall.

Terminology: The usage of venulák varies by language and publication; in English literature the equivalent term is venule. The diminutive form venulák is mostly encountered in Czech- and Slovak-language texts and is not universally standardized.