MEDICAL BIOLOGY, HUMAN ANATOMY, PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

CHAPTER 7. THE NUTRITIONAL PROCESS AND ITS PATHOLOGY

ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE ORGANS

SMALL INTESTINE

3. DIGESTION IN THE SMALL INTESTINE

3.1. INTESTINAL SECRETION

Intestinal glands are located in the mucous membrane of the duodenum and the entire Small Intestine. These glands secrete intestinal juice, which is a turbid, viscous, slightly alkaline fluid. About 1.8 liters of juice are produced daily. Intestinal juice contains Enzymes such as peptidases, lipase, amylase, maltase, and lactase. Peptidases break down Polypeptides into Amino Acids. Thus, the final Breakdown of Proteins into amino acids occurs in the intestine.

Intestinal juice contains up to 20 enzymes that participate in The final stage of Hydrolysis.

In addition to its digestive function, intestinal juice protects the mucous membrane, maintains chyme in a fluid state, and promotes an alkaline reaction of the intestinal contents. Intestinal juice is secreted reflexively only when chyme enters the intestine upon irritation of the mechanoreceptors and chemoreceptors of the mucosa.

Local mechanical and chemical irritation of the intestinal mucosa by chyme (products of protein and fat hydrolysis, acids) triggers reflexive juice secretion in the intestine. Parasympathetic nerves serve as the secretory nerves. The secretion of intestinal juice is enhanced by humoral mechanisms, specifically Hormones such as secretin, cholecystokinin-pancreozymin, and motilin.



Last update: 08/08/2026

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