Fluid in the small intestine

The "fluid in the small intestine" denotes the aqueous phase consisting predominantly of water, electrolytes (notably sodium, chloride, bicarbonate), mucus, and digestive enzymes present within the lumen of the small intestine. This fluid originates from ingested food and drink, as well as secretions from the intestinal glands (crypts of Lieberkühn), pancreas, liver (bile), and the intestine itself[1][5][3]. It is central to digestive physiology: providing a medium for enzymatic breakdown of nutrients, permitting nutrient and water absorption through transcellular and paracellular routes, and buffering the acidic contents arriving from the stomach[5][1][2]. Fluid balance in the small intestine is tightly regulated by a combination of osmotic gradients (created by active salt transport) and water channels such as aquaporins, as well as specific ion channels and co-transporters (including sodium-glucose cotransporters and chloride channels like CFTR)[2][6][4]. Dysregulation of intestinal fluid secretion or absorption underlies clinical conditions such as diarrhea and constipation[2][4][7]. In summary, "fluid in the small intestine" is a physiological compartment or phase, not a molecule or druggable target. Therefore, most canonical molecular classification fields do not apply.

Other names

Intestinal fluidSmall intestinal fluidLuminal fluid (small intestine)