EXTERNAL SECRETION — the type of secretion, at a cut a secret of glands is allocated through channels or for the surface of skin and mucous membranes, or in a cavity (a stomach, intestines, a nasopharynx, etc.). The pancreas, a liver, glands of a digestive tract, salivary, mammary, sexual, lacrimal, sweat and sebaceous glands, and also glands of mucous membranes of a nasopharynx, a trachea, bronchial tubes, a middle ear possess Vneshnesekretorny function. By means of allocated V.'s products of page there is a digestion of food, other secrets promote protection of bodies and fabrics, continuation of a look, etc.
V. of page arose as a way of removal of products of metabolism unnecessary an organism (excretion). Further improvement of an organism was followed by specialization of glands B. of page — development of ability to produce special secrets (a part of digestive secrets, the lacrimal liquid, a secret of sebaceous and mammary glands). Glands B. of page opening on the surface of skin (except for milk and grease), perform preferential excretory function. V.'s glands of page allocating the products in a cavity (except glands of a nasopharynx, bronchial tubes, a trachea), possess hl. obr. secretory function. However such division is conditional since structure of a secret, so, and fiziol, value of gland can change.
As membranes of glands B. of page have selective permeability and ability to actively transport some substances (see Membranes biological, Transport of ions), the secret of glands B. of page depends on composition of blood. If alien substances get to blood or the maintenance of natural components of plasma increases, then they are allocated with a secret of gland. So iodine, salts of heavy metals, some drugs are removed (Sergosinum, antibiotics, paints, etc.). High concentration them in a secret can cause pathological changes of gland (hypostasis, an inflammation, a hypertrophy). The research of excretion is used by glands of a stomach of paints (a Congo red, methylene blue) as diagnostic reception for assessment of a condition of these glands.
It is possible to explain with selective permeability of membranes of ferruterous cells and their ability to active transport of substances an origin of a secret of a number of glands of V. of page which includes as the cells of substance produced by the ferruterous device (e.g., a pepsinogen of fundal glands of a stomach), and the components passing into a secret from blood in finished form (bilious to - you, albumine, etc.). The special case of allocation by glands B. of page of the proferments (zymogens) which are contained in blood is represented by a rekretion. So, the pepsinogen of a peloric part of a stomach, amylase and a lipase of a stomach have a rekretorny origin.
One glands B. of page function continuously during all life (digestive, grease, stalemate, the lacrimal), others periodically — in connection with defined fiziol, a state (milk, sexual). Change of activity of glands of V. of page happens under the influence of specific and nonspecific influences. Carry irritants, adequate for these glands, to specific influences, napr, strengthening of secretion of digestive glands at meal, increase in secretion of milk during the feeding of a breast, etc. Nonspecific influences are connected with reorganization in all organism (change of secretion of digestive glands at physical. to work, strengthening of sweating at emotional pressure, etc.).
Regulatory influences on glands B. of page are carried out through nervous (c. N of page — the autonomic nervous system) and humoral (c. N of page — closed glands — allocation in blood of biologically active agents) are also expressed to a way finally in change of intensity of products of a secret and its qualitative structure, and also blood supply of gland, etc.
See also Secretion .
Bibliography: Babkin B. P. The secretory mechanism of digestive glands, the lane with English, L., 1960, bibliogr.; Kalantayevskaya K. A. Morphology and physiology of skin of the person, Kiev, 1972, bibliogr.; Korotko G. F. Release of enzymes glands of a stomach, Tashkent, 1971, bibliogr.; Physiology of digestion, under the editorship of A. V. Solovyov, etc., L., 1974, bibliogr.
Yu. V. Uryvayev.