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Metabolism of gut. Function of the small intestine . Absorption (monosaccharides, fat, aminoacids, vitamines, water, metals and trace elements) Defence against bacteria, toxines and antigen entry Hormone production Motility – transit of nutrients. Jejunum: Glucose and monosaccharides
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Function of the small intestine • Absorption (monosaccharides, fat, aminoacids, vitamines, water, metals and trace elements) • Defence against bacteria, toxines and antigen entry • Hormone production • Motility – transit of nutrients
Jejunum: Glucose and monosaccharides FA, glycerol, mono- acylglycerol,phospholipids Aminoacids Vitamines Electrolytes, Ca, Fe Ileum: Cholic acids B12 vit H2O, Na, K, …. Absorption in small intestine
Investigation of intestinal function: • Test of carbohydrate absorption: monosaccharides (D-xylose, L-rhamnose) are not metabolized in the body are excreted and in the urin is measured the content • Test of fat absorption: normaly is dietary fat absorbed in the small intestine. Pancreatic, hepatic and intestinal disease increased the fat content in faeces( normaly must be lower than 6g/24h). Triolein breath test: 13C-triolein substrate is metabolized and samples of expired 13CO2 : 12CO2 are measured. • Aminoacid absorption: malabsorption of specific AA occures in inherited metabolis diseases
Deficit microvillar enzymes: alactasia,sucrase-isomaltase deficit Pancreatic enzymes deficiency:protein lossing enterophaty Bile salt deficiency: steatorhea Deficit of transport mechanism: Anemia (Fe, folic acid, B12) Osteomalacia (Ca, D vitamin) Aminoacids Decreased absorption of nutrients: malabsorption
Most ingestet food is absorbed in small intestine, the residue passes into large intestine: • Bacteria produce gases: CO2, CH4, H2, H2S, NH3, acetic, lactic, propionic and butyric acid • H2O is absorbed • Ions are absorbed • End material is excreated in form of stool
The main role of the colon is the absorption of water and electrolytes. Input and output of water and electrolytes in the GI over 24 h
Stool • Volume: <200g/d (higher volume is in malabsorption) • Dry weight make 30% • Composition:25% minerals (Na, K, Cl, Ca, PO4, Fe, Cu, Mn, Zn, I) • 25% intestinal flora • 50% organic components
Stool • pH-neutral:(acidic pH 5,5 by microbial dyspepsia) • Color: from bile pigments – urobilin and stercobilin. Newborns – bilirubin • Odour: gases and scatol, indol, thiomethan • Enzymes: trypsin, chymotrypsin, elastase • Toxic and neurotoxic metabolites: H2S, NH3, diamines, tyramin, neurin