Gland
A gland is an organ or tissue composed of specialized secretory cells that produce chemical substances for use within the body or for elimination. Glands can be unicellular, such as goblet cells, or multicellular with organized secretory units. They are typically classified by where their secretions go: exocrine glands release through ducts onto an epithelial surface or into a body cavity; endocrine glands release hormones directly into the bloodstream and lack ducts.
Exocrine glands include the salivary, sweat, lacrimal, and many digestive glands. They secrete enzymes, mucus, or
Structure and secretion mechanisms vary: glands have secretory units (acini or tubules) made of secretory cells,
Regulation of secretion involves neural input and hormonal feedback. Endocrine secretions are often governed by feedback
Clinical notes: gland dysfunction can cause hyper- or hyposecretion, atrophy, or tumors such as adenomas or