SISTEMA DIGESTIVO

SISTEMA DIGESTIVO: bioreactores

SISTEMA DIGESTIVOEs un tubo abierto: extensión del medio ambiente!E S

absorción

Digestión: •mecánica (trituración)•química (enzimas hidrolíticas)

- Direccionalidad

- Compartimentalización

- Almacenamiento.

Sistema de Tubos y Esfínteres

EL TRACTO DIGESTIVO

Anatomía del sistema Anatomía del sistema digestivodigestivo

Digestive tractDigestive tract Alimentary tract or Alimentary tract or

canalcanal GI tractGI tract

Accessory Accessory organsorgans Primarily glandsPrimarily glands

RegionsRegions Mouth or oral cavityMouth or oral cavity PharynxPharynx EsophagusEsophagus StomachStomach Small intestineSmall intestine Large intestineLarge intestine AnusAnus

Cavidad oralCavidad oral Mouth or oral Mouth or oral

cavitycavity VestibuleVestibule: Space : Space

between lips or between lips or cheeks and alveolar cheeks and alveolar processesprocesses

Oral cavity properOral cavity proper Lips (labia) and Lips (labia) and

cheekscheeks PalatePalate: Oral cavity : Oral cavity

roofroof Hard and soft Hard and soft

Palatine tonsilsPalatine tonsils TongueTongue: Involved in : Involved in

speech, taste, speech, taste, mastication, mastication, swallowingswallowing

DientesDientes

DientesDientes

Two setsTwo sets Primary, deciduous, Primary, deciduous,

milk: Childhoodmilk: Childhood Permanent or Permanent or

secondary: Adult secondary: Adult (32)(32)

TypesTypes Incisors, canine, Incisors, canine,

premolar and premolar and molarsmolars

Glándulas salivalesGlándulas salivales Produce salivaProduce saliva

Prevents bacterial Prevents bacterial infectioninfection

LubricationLubrication Contains salivary Contains salivary

amylaseamylase Breaks down starchBreaks down starch

Three pairsThree pairs Parotid: LargestParotid: Largest SubmandibularSubmandibular Sublingual: Sublingual:

SmallestSmallest

Producción de saliva

- 99.5 % agua

-HCO3- , ph 6.5

-moco, enzimas

SECRECIONES SALIVALES

1. Secreción serosa: amilasa salival:

hidrólisis -1-4 polisacáridos

2.Secreción mucosa:

lubrica y protege.

3.IgA y lisozima:

antimicrobiana

Reflejo de degluciónReflejo de deglución

Fase voluntaria

Bolo alimenticio desde boca a faringe

Fase refleja

Apertura del esófago, cierre de laringe

Fase refleja

Transporte por esófago

Histología del tracto Histología del tracto digestivodigestivo

Peritoneo y Peritoneo y MesenteriosMesenterios

PeritoneumPeritoneum VisceralVisceral: Covers organs: Covers organs ParietalParietal: Covers interior : Covers interior

surface of body wallsurface of body wall RetroperitonealRetroperitoneal: Behind : Behind

peritoneum as kidneys, peritoneum as kidneys, pancreas, duodenumpancreas, duodenum

MesenteriesMesenteries Routes which vessels Routes which vessels

and nerves pass from and nerves pass from body wall to organsbody wall to organs

Greater omentumGreater omentum Lesser omentumLesser omentum

EstómagoEstómago

OpeningsOpenings GastroesophaGastroesopha

gealgeal: To : To esophagusesophagus

PyloricPyloric: To : To duodenumduodenum

RegionsRegions CardiacCardiac FundusFundus BodyBody PyloricPyloric

Histología del Histología del estómagoestómago

LayersLayers Serosa or visceral Serosa or visceral

peritoneum: peritoneum: OutermostOutermost

Muscularis: Three Muscularis: Three layerslayers

Outer longitudinalOuter longitudinal Middle circularMiddle circular Inner oblique Inner oblique

SubmucosaSubmucosa MucosaMucosa

Gastric pits and Gastric pits and glandsglands: : Contain cellsContain cells

Surface mucous: Surface mucous: MucusMucus

Mucous neck: Mucous neck: Mucus Mucus

Parietal: Parietal: Hydrochloric acid Hydrochloric acid and intrinsic factor and intrinsic factor

Chief: Pepsinogen Chief: Pepsinogen Endocrine: Endocrine:

Regulatory Regulatory hormoneshormones

Secreción de HCl Secreción de HCl en células parietalesen células parietales

Barrera mucus – HCO3Barrera mucus – HCO3--

Fases de la Fases de la secreción secreción gástricagástrica

FASE CEFÁLICAFASE CEFÁLICA- percepción sensorial del alimento- percepción sensorial del alimento

FASE GÁSTRICAFASE GÁSTRICA- presencia del alimento- presencia del alimento

Ondas de mezclaOndas de mezcla

FASE INTESTINALFASE INTESTINAL

VIP

Gastrin

Duodeno y PancreasDuodeno y Pancreas

PancreasPancreas

AnatomyAnatomy EndocrineEndocrine

Pancreatic islets Pancreatic islets produce insulin and produce insulin and glucagon glucagon

ExocrineExocrine Acini produce Acini produce

digestive enzymes digestive enzymes and HCO3-and HCO3-

RegionsRegions: Head, : Head, body, tailbody, tail

SecretionsSecretions Pancreatic juice Pancreatic juice

(exocrine)(exocrine) TrypsinTrypsin ChymotrypsinChymotrypsin CarboxypeptidaseCarboxypeptidase Pancreatic amylasePancreatic amylase Pancreatic lipasesPancreatic lipases ElastaseElastase Nucleases (DNA, Nucleases (DNA,

RNA)RNA) HCO3-, H20HCO3-, H20

Secreción de HCO3-Secreción de HCO3-

EnzimasEnzimas

TrypsinogenTrypsinogen ChymotrysinogenChymotrysinogen CarboxypeptidasCarboxypeptidas

eses Pro-elastasePro-elastase PhospholipasePhospholipase pancreatic lipasepancreatic lipase Pancreatic Pancreatic

amylaseamylase

HígadoHígado LobesLobes

MajorMajor: Left and right: Left and right MinorMinor: Caudate and : Caudate and

quadratequadrate DuctsDucts

Common hepaticCommon hepatic CysticCystic

From gallbladderFrom gallbladder Common bileCommon bile

Joins pancreatic duct Joins pancreatic duct at hepatopancreatic at hepatopancreatic ampullaampulla

Figure 24.20a, b

Histología del hígadoHistología del hígado

triadaportal

Funciones del hígadoFunciones del hígado Bile productionBile production

Salts emulsify fats, contain pigments as bilirubinSalts emulsify fats, contain pigments as bilirubin

StorageStorage Glycogen, fat, vitamins, copper and ironGlycogen, fat, vitamins, copper and iron

Aminoacid synthesisAminoacid synthesis Cholesterol and tryglicerid synthesisCholesterol and tryglicerid synthesis Gluconeogénesis, glucogénesis, Gluconeogénesis, glucogénesis,

glucogenólisisglucogenólisis Hepatocytes remove ammonia and convert to ureaHepatocytes remove ammonia and convert to urea

PhagocytosisPhagocytosis Kupffer cells phagocytize worn-out and dying red and white blood Kupffer cells phagocytize worn-out and dying red and white blood

cells, some bacteriacells, some bacteria

Plasma proteins and hemostatic factorsPlasma proteins and hemostatic factors Albumins, globulins, fibrinogen, heparin, K vitaminAlbumins, globulins, fibrinogen, heparin, K vitamin

Detoxification and drug Detoxification and drug metabolismmetabolism Hormonal secretion: trombopoietin, Hormonal secretion: trombopoietin, angotensinogenangotensinogen

BilisBilis

Bile acidBile acid PhospholipidsPhospholipids CholesterolCholesterol BilirubinBilirubin Waste productsWaste products ElectrolytesElectrolytes MucinMucin HCO3-HCO3-

…each day around 600 ml of bile is produced…

ConductosConductos

Intestino delgadoIntestino delgado Site of greatest Site of greatest

amount of digestion amount of digestion and absorptionand absorption

Divisions Divisions DuodenumDuodenum JejunumJejunum Ileum: Peyer’s patches Ileum: Peyer’s patches

or lymph nodulesor lymph nodules ModificationsModifications

Circular folds or plicae Circular folds or plicae circulares, villi, lacteal, circulares, villi, lacteal, microvillimicrovilli

Cells of mucosaCells of mucosa Absorptive, goblet, Absorptive, goblet,

granular, endocrinegranular, endocrine

Secreciones del int. Secreciones del int. delgadodelgado

Mucus and HCO3-Mucus and HCO3- Protects against digestive enzymes and Protects against digestive enzymes and

stomach acidsstomach acids EnzymesEnzymes

DisaccharidasesDisaccharidases PeptidasesPeptidases Nucleotidases, nucleosidasesNucleotidases, nucleosidases Enteroquinase: tripsinógeno Enteroquinase: tripsinógeno tripsina tripsina

Duodenal glands (Brünner)Duodenal glands (Brünner) Stimulated by vagus nerve, secretin, chemical Stimulated by vagus nerve, secretin, chemical

or tactile irritation of duodenal mucosaor tactile irritation of duodenal mucosa

DuodenoDuodenollegan: quimo ácido, jugos llegan: quimo ácido, jugos

pancreáticos, bilispancreáticos, bilis

Absorción intestinalAbsorción intestinal

MonosacáridosMonosacáridos

LípidosLípidos

LipoproteinasLipoproteinas

TypesTypes ChylomicronsChylomicrons

Enter lymphEnter lymph VLDLVLDL LDLLDL

Transports Transports cholesterol to cellscholesterol to cells

HDLHDL Transports Transports

cholesterol from cholesterol from cells to livercells to liver

Intestino gruesoIntestino grueso

Extends from ileocecal junction to anusExtends from ileocecal junction to anus Consists of cecum, colon, rectum, anal canalConsists of cecum, colon, rectum, anal canal Movements sluggish (Movements sluggish (18-24 hours18-24 hours))

Intestino grueso: Absorción Intestino grueso: Absorción de Hde H22O y DefecaciónO y Defecación

Figure 21-27: Anatomy of the large intestine

Large IntestineLarge Intestine

CecumCecum Blind sac, vermiform appendix attachedBlind sac, vermiform appendix attached

ColonColon Ascending, transverse, descending, sigmoidAscending, transverse, descending, sigmoid

RectumRectum Straight muscular tubeStraight muscular tube

Anal canalAnal canal Internal anal sphincter (smooth muscle) Internal anal sphincter (smooth muscle) External anal sphincter (skeletal muscle) External anal sphincter (skeletal muscle)

Histology of Large Histology of Large IntestineIntestine

Figure 21-28: NaCl reabsorption by colonocytes

Water and Water and electrolyte electrolyte secretion &/or secretion &/or absorptionabsorption

Bacterial Bacterial fermentation of fermentation of HCHC

Bacterial Bacterial synthesis of Vit. synthesis of Vit. K , B.K , B.

Bacterial Bacterial degradation of degradation of bile acids and bile acids and esterolsesterols

Absortion of Absortion of lactate & butyratelactate & butyrate

Prevents Prevents infections and infections and immune immune alterations alterations

Figure 21-29: NaCl secretion by colonic crypt cells

Toxina coléricaToxina colérica- ADP-ribosilación de G G-GTP AC cAMP PKA p-

CFTR

PKA

SecrecionesSecreciones

Mucus provides protectionMucus provides protection Parasympathetic stimulation increases rate Parasympathetic stimulation increases rate

of goblet cell secretionof goblet cell secretion PumpsPumps

Exchange of bicarbonate ions for chloride Exchange of bicarbonate ions for chloride ionsions

Exchange of sodium ions for hydrogen ionsExchange of sodium ions for hydrogen ions Bacterial actions produce gases called Bacterial actions produce gases called

flatusflatus

Reflejos enReflejos en Colon y Colon y RectoRecto

Secreciones del tubo Secreciones del tubo digestivodigestivo

Enzimas del tubo Enzimas del tubo digestivodigestivo

Regulación nerviosa y Regulación nerviosa y hormonalhormonal

Nervous regulationNervous regulation Involves enteric Involves enteric

nervous systemnervous system Types of neurons: Types of neurons:

sensory, motor, sensory, motor, interneuronsinterneurons

Coordinates Coordinates peristalsis and peristalsis and regulates local regulates local reflexesreflexes

Chemical regulationChemical regulation Production of Production of

hormoneshormones Gastrin, secretinGastrin, secretin

Production of Production of paracrine chemicalsparacrine chemicals

Histamine Histamine Help local reflexes in Help local reflexes in

ENS control digestive ENS control digestive environments as pH environments as pH levels levels

Regulating Digestion: CNS Regulating Digestion: CNS and Enteric Nervous and Enteric Nervous

System (ENS)System (ENS)

Figure 21-9: The enteric nervous system

Hormonas gastrointestinalesHormonas gastrointestinales