darmsappen

Darmsappen, or intestinal juice, is a watery, alkaline digestive secretion produced by glands of the mucosa in the small intestine, mainly in the crypts of Lieberkühn, with mucus contributed by goblet cells. It is released into the intestinal lumen in response to chyme, neural input, and hormonal signals, and it occurs throughout the duodenum, jejunum, and ileum.

The composition of darmsappen includes water, electrolytes (notably bicarbonate), mucus, and a set of brush-border enzymes. The digestive enzymes present include disaccharidases (such as lactase, sucrase, and maltase) and peptidases (aminopeptidases and dipeptidases) that complete carbohydrate and protein digestion in the lumen. The enzyme enteropeptidase (enterokinase) is also associated with the intestinal mucosa and activates certain pancreatic enzymes. Lipid digestion is primarily carried out by pancreatic enzymes and bile acids, while the intestinal juice provides a suitable luminal environment and mucosal protection.

Functionally, darmsappen supports the final steps of digestion in the small intestine, producing monosaccharides and small peptides that can be absorbed by enterocytes. It works in concert with pancreatic enzymes, bile, and the absorptive processes of the mucosa. The bicarbonate content helps neutralize gastric acid, protecting the mucosa and optimizing enzyme activity.

Regulation of intestinal juice secretion involves secretin (which stimulates bicarbonate-rich fluid), cholecystokinin (which promotes enzyme-rich secretion from the pancreas and slows gastric emptying), and parasympathetic input. Clinically, deficiencies in brush-border enzymes (e.g., lactase) cause intolerance symptoms despite the presence of darmsappen.