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FISIOLOGIA DIGESTIVAFISIOLOGIA DIGESTIVA
FISIOLOGÍA DIGESTIVA (BCM II)FISIOLOGÍA DIGESTIVA (BCM II)
Dr. Michel Baró AlisteDr. Michel Baró Aliste
Clase 11: Digestión y absorción de nutrientes
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Oral cavity has important functions in initial processing
TABLE 2 - 4. DIGESTION STARTS IN THE ORAL CAVITY
Mastication–Mechanical disruption of solid food
Increased salivary secretion–Moistening of food particles and mixing with salivary amylase, R - factors, and lingual lipase
Taste of food–Increased stimulation of gastric secretion
Swallowing of food bolus
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Macronutrient digestion and absorption proceed at rapid pace
95%
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The primary bile acids, cholic and chenic acid
Recirculaciónentero-hepáticade las sales biliares:dos veces por cadacomida.
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Lipids have highest energy content of 3 macronutrients
a-grasos esenciales:ac.linoleicoac.linolénico
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The initial event in lipid digestion in the stomach
Formación de gotasde emulsiónpH 4-5,5
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Carbohydrate is the major energy source in the diet
+sucrosa+lactosa
400 g/día
Endoglucosidasas
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Oligopeptides and amino acids generated by intraluminal proteolysis
TABLE 2 - 25. BRUSH - BORDER OLIGOPEPTIDE HYDROLYSIS
Brush - Border Enzymes Substrate Products
Endopeptidases
Enteropeptidase Trypsinogen Trypsin
Endopeptidase 24.11 Hydrophobic AA Peptides
Neutral endopeptidase ? Peptides
Exopeptidases
Aminopeptidase N Neutral AA Neutral AA
Di - and tripeptides
Aminopeptidase A Acidic AA Acidic AA
Dipeptidylpeptidase IV Penultimate proline Dipeptides
Gly - Leu peptidase Dipeptide (Aliphatic) AA
Asp - Lys peptidase Dipeptide (Basic) AA
Folate Conjugase Polyglutamated Folates Folic Acid
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Proteolytic enzymes are secreted in vast excess by pancreas
bás.
arom.
alif.
bás.
neut.
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Amino acid transport systems
TABLE 2 - 28. AMINO ACID TRANSPORTSYSTEMS IN ENTEROCYTES
Brush
BorderBasolateralMembrane
Amino AcidSpecificity
SodiumCoupled
A A Neutral +
ASC ASC Neutral +
B Neutral +
BO,+ Neutral +
bO,+ bO,+ Neutral -
Imino Proline +
L L Branched AA -
X - Asp, Glut +
Y+AG Y+ Arg, Lys -
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Folate is present in food, primarily in polyglutamate form
(exopeptidasa)
(hidrosolubles)
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Trace elements are important constituents of diet
TABLE 2 - 32. TRACE ELEMENT ABSORPTION
Daily Intake, MG Amount Absorbed, %
Zinc 10 - 15 20 - 50
Copper 1 - 3 30 - 70
Selenium 0.1 - 0.2 ?
Manganese 2 - 5 15 - 25
Uptake processes of trace elements are poorly defined–presumably both carrier - mediated transport and passive diffusion play a role.