1-05-GI2stomac

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Cat. de Fiziologie, UMF Bucuresti

2005/2006 – Dr. Dan Ferechide



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Rolurile HCL• Asigura Ph• PG-Pepsina• Activare proteine• Fe activare• B12 activare• Proteine –anemie• Sterilizare• Motilitate• Ionizare AG-tg• Evacuare g-d• Reglare digestiva: Se, CCK,Ga,





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Substantele organice in sucul gastric

Proteinele-enzimePepsinogenul-pepsina

Lipaza gastricaReninaUreaza

A.c. Lizozimul



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Proteine non- E

• Proteine plasmatice: albumine• Imunoglobuline A;M,G• Ag ABO• Mucusul –MPZ,GP (gastrona)• Factor intrinsec,complex R-B12



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FAZA CEFALICA-30-40%HCL

Reflexe cond.: miros,vaz.gust, gandauz,D,MReflexe nec: alimente in CB-X(NMDB)-PS-41-ACH in corp g-MCP-HCL(M3)2-ACHX in corp-corion-M3ECL-HIS-HCL(P3-Antral X-GRP(SNE)-GCel-GastrinaHCL(2)4-Corp si antru X-(-)D Cel –SS(-)Gastrina-HCL

creste si 3o-40% acid pe stomac gol!!Faza e nervoasa 90%, minute





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Gastrina (5O-2OO pg/ml)• Activatori• Ph i.g antral > 3• Proteine tampon->3• His,ser,ala,gli,lis,trip,pp,AI,AII in chim• Vag –ACH-M3• Distensia antrala,-SNE• Ca siCa /Lic• Subst.P si PP• Histamina• Nora, adr, stress, dopa• Saruri biliare, alcool,



INHIBITORI AI ELIBERARII GASTRINEI

• Somatostatina din antru si corp (D)• Scadere pH i.g. antral la 1,5-2-2,5• HCl crescut• Glucagonul si enteroglucagonul (st, D)• Gastrona (glicoproteina – mucus)• PGE1,2 inhiba HCl+Ga• GIP, VIP, secretina• Reflexe inhibitoare antrofundice• Vagolitice, antagonisti CCKB - proglumid



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EFECTE FIZIOLOGICE - GASTRINA

• Creste secretia HCl si de PG • Creste sectretia mucus• Stimuleaza cresterea mucoasei gastrice – efect trofic (ADN)• Regleaza sucul Pa – ecbolic cu CCK• Creste secretia F.intrinsec• Creste fluxul biliar• Stimuleaza motilitatea digestiva (evacuarea G)• Reglarea insulinei• Stimuleaza SEI (tonus), creste fluxul sanguin splanhnic• Creste eliberarea de histamina



HISTAMINA

• Surse: bazofile, mastocite, trombocite si ECL• Actioneaza prin receptori H2 la organe si celule (P, p)• Este eliberata de: AMP ciclic, Ca+2, ACH, gastrina etc.• Mecanism de actiune: H2 – RCPGs – AC – 3,5 AMP – PKA • Raspuns secretor HCl – proportional MCP (Kay)• Blocantii H2 trateaza UD: nizatidina – AXID• Efecte: creste volumul secretiei G, secretia HCl (DAM)• Creste secretia de pepsina, FI, VD in circulatia gastrica



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FAZA GASTRICA -50-55% HCL S

• Intrarebol-2stimuli-distensia si PDP –Efect+• Mecanorec. declansaza,reflexe locale si x-x• Ach+GRP+COT-cele 4 cai vagale:1,2,3,4.• ENS-reflexe locale• PDP, AA, FENAL, TR,PEPTONE, antrale-G17• Ce elibereaza gastrina-cel.P-HCL-PG-PEPSIN-digest-

PDP-GA-Feed-back +• GA-ECL-HIS(IMUN)-HCL-PH scade<2• Efect-Feed-back-; ph<2-3-antral D-SS cell care – G –

GA(-)siHCL scade, ph-ul urca(inhibitie-paracrinaGA-• si endocrin PG si HCL



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ROLUL SNE

• Un minicreier cu neuroni senzitivi, motori, interneuroni• Numar de neuroni – MS dispusi in 5 plexuri• Activitate independenta si modulata de PS si OS• Plexurile mucos si submucos inchid reflexe secretorii• Neuronii senzitivi – variatii luminale: distensie, chinie (pH,

osm, T°, AA) – interneuroni, neuron eferent secreto-motor• Raspunsuri reflexe locale preprogramate• Input de la creier, hipo T, bulb – via nerv vag• Neurotransmitatori: ACH, VIP, Enk, SS, SP, NO, 5HT



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FAZA INTESTINALA – chim in duoden5 – 10 % din HCl total-Evacuare totala

• A) cand pHD>3 – influente stimulatoare• Mecanism predominent umoral declansat de: 1) distensia D – gastrina D (10%) G34

+ 2) AA, PP – gastrina – sange – celule P–HCl; 3) AA, PP absorbite – sange – antru– G antral – celule P – HCl; 4) peptonele, AA stimuleaza celule intestinaleendocrine – enterooxintina – sange – celule P – HCl; 5) GRP, beta – endorfine –SNE – cresc Ga

• B) cand pHD<3(2) – prin consumarea capacitatii de tamponare a chimului de catreduoden (bila, SP)

• Predomina influentele inhibitorii de protectie antiacida – mecanisme umoraleinhibitorii ale secretiei gastrice acide

• 1) pHD (<3-4) inhiba gastrina si HCl• 2) Grasimi si produsi lipidici (MG, AGL cu > 10C) si solutiile hipertone, glucozate• Mecanismele sunt nervoase (simpatic), vagale (NANC), mai ales umorale





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MECANISME UMORALE INHIBITORII – FAZA INTESTINALA

• SS (28AA) inhiba HCl prin doua mecanisme:D Cel-D,J,I• - direct pe celula parietala – scade AC – scade PKA– HCl• - scade efectul ECL pe MCP (endocrin) in stomac(SSSinge• -cuplul celula D-SS-Cel G-Gastrina in duoden –feed-back• Enteroglucagon-L-Celule ileale,colon-singe-HCLscade• Glucagon idem• MG+AG in D si jejun elibereaza GIP, CCK, scad HCL• Hipertonia chimului –Bulbogastrona – HCL scade• Substanta P-11 AA-Colocatar SNE: Ach, Epi, Dopa, glu



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