Download Metabolisms of gut

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
Absorption in small intestine
Jejunum:
Glucose and
monosaccharides
FA, glycerol, monoacylglycerol,phospho
lipids
Aminoacids
Vitamines
Electrolytes, Ca, Fe
Ileum:
Cholic acids
B12 vit
H2O, Na, K, ….
Investigation of intestinal
function:
Test of carbohydrate absorption: monosaccharides (D-xylose, Lrhamnose) 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
Decreased absorption of nutrients:
malabsorption
Deficit microvillar
enzymes:
alactasia,sucraseisomaltase 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
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
INPUT Water ml Na mmol K mmol
Diet
1500
150
80
GI
secretion
7500
1000
40
Total
9000
1150
120
150
5
12
Out put
Faeces
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