metabolism of gut. function of the small intestine absorption (monosaccharides, fat, aminoacids,...
TRANSCRIPT
Metabolism of gut
Function of the small intestine
Absorption (monosaccharides, fat, aminoacids, vitamines, water, metals and trace elements)Defence against bacteria, toxines and antigen entryHormone productionMotility – transit of nutrients
Absorption in small intestine
Jejunum:Glucose and monosaccharidesFA, glycerol, mono- acylglycerol,phospholipidsAminoacidsVitaminesElectrolytes, Ca, Fe
Ileum:Cholic acidsB12 vitH2O, Na, K, ….
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 contentTest 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
Decreased absorption of nutrients: malabsorption
Deficit microvillar enzymes: alactasia,sucrase-isomaltase deficitPancreatic enzymes deficiency:protein lossing enterophaty Bile salt deficiency: steatorhea
Deficit of transport mechanism:Anemia (Fe, folic acid, B12)Osteomalacia (Ca, D vitamin)Aminoacids
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 acidH2O is absorbed
Ions are absorbedEnd 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
INPUT Water ml Na mmol K mmol
Diet 1500 150 80
GI secretion
7500 1000 40
Total 9000 1150 120
Out putFaeces 150 5 12
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 – bilirubinOdour: gases and scatol, indol, thiomethanEnzymes: trypsin, chymotrypsin, elastaseToxic and neurotoxic metabolites: H2S, NH3, diamines, tyramin, neurin