glandele

Glandele are glands, organs that synthesize and secrete substances for use inside the body or on external surfaces. In humans and other animals, glands are classified by their mode of secretion into exocrine and endocrine glands. Exocrine glands release secretions through ducts to epithelial surfaces, as seen in the salivary, lacrimal, sebaceous, and sweat glands. Endocrine glands release hormones directly into the bloodstream, with examples including the pituitary, thyroid, adrenal glands, pancreas (islets), and gonads.

Gland structure can be tubular, acinar (alveolar), or tubuloacinar, and glands may be simple or compound. Some glands are unicellular, such as goblet cells, which secrete mucus directly onto mucosal surfaces. Secretory mechanisms include merocrine secretion (via exocytosis), apocrine secretion (loss of a portion of the cell membrane), and holocrine secretion (cell rupture).

Gland activity is regulated by neural input and hormonal signals and adapts to physiological needs. Dysfunction can lead to disorders of secretion, such as hypo- or hypersecretion, autoimmune conditions, inflammatory diseases, or neoplasms. Glandele play essential roles in digestion, lubrication, protection, thermoregulation, and homeostasis, reflecting their diversity across tissues and organisms.