FISIOLOGIA DIGESTIVA

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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


Nutrients provided by animal and vegetable products


Digestive process is initiated by sensory signals


The effect of discussion, sight, and smell of food


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


The arrival of a swallowed food bolus in the stomach


The emptying of food from the stomach


Passage of acidic, hyperosmolar gastric chyme into duodenum


Cholecystokinin and secretin are of major importance


Macronutrient digestion and absorption proceed at rapid pace

95%


Large bowel: role in carbohydrate digestion and absorption


The primary bile acids, cholic and chenic acid

Recirculaciónentero-hepáticade las sales biliares:dos veces por cadacomida.


Lipids have highest energy content of 3 macronutrients

a-grasos esenciales:ac.linoleicoac.linolénico


The initial event in lipid digestion in the stomach

Formación de gotasde emulsiónpH 4-5,5


Lipid digestion proceeds at a rapid pace in duodenum


Bile acids are amphipaths


Transport of lipolytic products


The lipolytic products are resynthesized

acetil-coA


End products of lipid absorption in the enterocytes


Carbohydrate is the major energy source in the diet

+sucrosa+lactosa

400 g/día

Endoglucosidasas


Products of starch digestion and two dietary disaccharides


Glucose, galactose, and fructose are not lipid soluble


Protein digestion begins in the stomach


Average daily protein intake is about 70-100 g in adults


The proteolytic enzymes secreted by pancreatic acini


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


Proteolytic enzymes are secreted in vast excess by pancreas

bás.

arom.

alif.

bás.

neut.


Dipeptides, tripeptides, and amino acids


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 -


Vitamin B12 is one of water-soluble vitamins


Folate is present in food, primarily in polyglutamate form

(exopeptidasa)

(hidrosolubles)


Daily intake of 3 major minerals in the diet


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.


Fin

FISIOLOGIA DIGESTIVA

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