Klierunits

Klierunits, or gland units, are the basic structural and functional elements of glands, the organs that produce and release substances such as enzymes, mucus, hormones, or bile. A gland’s activity depends on the organization of its secretory portions, ducts, and supporting tissue, all arranged to deliver secretions to their site of action or into the bloodstream.

In exocrine glands, secretions are transported through ducts to external surfaces or body cavities. Their gland units are often acini (clusters of secretory cells) or tubules. Acinar cells may be serous or mucous, reflecting the composition of the secretion. The secretory cells sit on a basement membrane and can be surrounded by myoepithelial cells that help expel secretions.

In endocrine glands, the secretory units release products directly into the circulatory system. The units may be cords, follicles, or islets, depending on the organ. The pancreas illustrates both patterns, with pancreatic acini secreting enzymes into ducts and the islets of Langerhans releasing hormones into capillaries.

Common features across gland units include a specialized epithelium, a supporting connective tissue framework, and an extensive vascular supply that carries secretions away. The term klierunits is used in some languages or contexts to describe these fundamental building blocks of glandular tissue, regardless of whether the gland is exocrine or endocrine.