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intestinal juice[in′tes·tən·əl ¦jüs]
the secreta of glands of the small and large intestines; a colorless or yellowish fluid with an alkaline reaction and containing clumps of mucous and cast-off epithelial cells.
Man secretes 1–3 liters of intestinal juice a day, depending on the type of food eaten and the individual’s physical condition. Intestinal juice is secreted continuously, in response to mechanical stimulation of the mucous membrane by the intestinal content, or chyme. The density of the juice in man and animals varies from 1.007 to 1.009. Intestinal juice is composed of water and organic and inorganic substances; the solid residue (1.2–1.5 percent) is similar in composition to the cells of the cast-off epithelium. Small amounts of enzymes are found in intestinal juice: amylase, saccharase, maltase, amino peptidases, enterokinase, monoglyceride lipase, phosphatase, and nucleotidase. These enzymes are absent only in the distal portions of the large intestine.
Intestinal secretion is regulated by nervous and humoral mechanisms. The parasympathetic (cholinergic) division of the autonomic system stimulates intestinal secretion; the sympathetic (adrenergic) division inhibits it.
N. M. TIMOFEEVA