Sekretjon

Sekretjon is a biological process in which cells synthesize and release substances for use inside the organism or for export. It encompasses the secretion of enzymes, hormones, mucus, and other fluids. Secretory cells line glands and epithelia throughout the body, and the substances may be released into ducts, into body cavities, or directly into the bloodstream.

Mechanisms and types: Most secretions are released by exocytosis of secretory vesicles. Secretion can be merocrine, apocrine, or holocrine, depending on how the secretory product is released. The process often involves synthesis in the endoplasmic reticulum and Golgi apparatus, packaging into vesicles, and transport to the plasma membrane. Secretions are regulated by internal signals such as hormones and neural inputs, and by feedback from target tissues.

Examples and functions: Exocrine secretions include saliva, sweat, and digestive enzymes that act locally or within the digestive tract; endocrine secretions such as insulin, cortisol, and thyroid hormones are released into the bloodstream to regulate distant targets. Mucous secretions protect and lubricate surfaces. The balance and timing of sekretjon are essential for digestion, metabolism, immune defense, and tissue maintenance.

Clinical relevance: Abnormal sekretjon is associated with various disorders. Impaired insulin secretion is central to diabetes mellitus; reduced saliva secretion can cause dry mouth; pancreatic enzyme secretion deficits affect digestion. Treatments may include medications that stimulate secretion, enzyme replacement, or therapies that modify gland function.

See also: secretion, exocytosis, endocrine system, exocrine glands.