secretion

A general term used to describe the products of glands in animals and plants. Glands such as the thyroid, testes, ovaries, adrenals, pituitary synthesize hormones which they excrete into the bloodstream. These are endocrine glands. Other glands include sweat, prostate, lachrymal, and Bartholin's glands. These are exocrine glands which excrete their products into places other than the bloodstream. The pancreas and stomach are unusual in that their secretions contain both endocrine (insulin) and exocrine (digestive) hormones. The female breast secretes milk and is an exocrine gland. The testis is a highly specialised mixed gland with both endocrine (testosterone) and exocrine (sperm)functions. The female ovary is a specialised mixed gland also. The word is also used loosely to describe mucous-like substances which are transudates or exudates. These are substances derived from fluid in the tissues and which are driven across a membrane e.g. vaginal wall by a pressure gradient - usually blood pressure but could be osmotic. Secretions may become profuse during illness e.g. common cold as the body attempts to wash away the infective agent.