SISTEMA DIGESTIVO SISTEMA DIGESTIVO bioreactores SISTEMA DIGESTIVO Es

SISTEMA DIGESTIVO

SISTEMA DIGESTIVO: bioreactores

SISTEMA DIGESTIVO Es un tubo abierto: extensión del medio ambiente! S E absorción Digestión: • mecánica (trituración) • química (enzimas hidrolíticas)

Sistema de Tubos y Esfínteres - Direccionalidad - Compartimentalización - Almacenamiento.

EL TRACTO DIGESTIVO

Anatomía del sistema digestivo n Digestive tract n n n Accessory organs n n Alimentary tract or canal GI tract Primarily glands Regions n n n n Mouth or oral cavity Pharynx Esophagus Stomach Small intestine Large intestine Anus

Cavidad oral n Mouth or oral cavity n n Lips (labia) and cheeks Palate: Oral cavity roof n n n Vestibule: Space between lips or cheeks and alveolar processes Oral cavity proper Hard and soft Palatine tonsils Tongue: Involved in speech, taste, mastication, swallowing

Dientes

Dientes n Two sets n n n Primary, deciduous, milk: Childhood Permanent or secondary: Adult (32) Types n Incisors, canine, premolar and molars

Glándulas salivales n Produce saliva n n n Prevents bacterial infection Lubrication Contains salivary amylase n n Breaks down starch Three pairs n n n Parotid: Largest Submandibular Sublingual: Smallest

Producción de saliva - 99. 5 % agua - HCO 3 - , ph 6. 5 - moco, enzimas

SECRECIONES SALIVALES 1. Secreción serosa: amilasa salival: hidrólisis a-1 -4 polisacáridos 2. Secreción mucosa: lubrica y protege. 3. Ig. A y lisozima: antimicrobiana

Reflejo de deglución Fase voluntaria Fase refleja Bolo alimenticio desde boca a faringe Apertura del esófago, cierre de laringe Transporte por esófago

Histología del tracto digestivo

Peritoneo y Mesenterios n Peritoneum n n Visceral: Covers organs Parietal: Covers interior surface of body wall Retroperitoneal: Behind peritoneum as kidneys, pancreas, duodenum Mesenteries n n n Routes which vessels and nerves pass from body wall to organs Greater omentum Lesser omentum

Estómago n Openings n n n Gastroesophageal: To esophagus Pyloric: To duodenum Regions n n Cardiac Fundus Body Pyloric

Histología del estómago n Layers n n Serosa or visceral peritoneum: Outermost Muscularis: Three layers n n n Outer longitudinal Middle circular Inner oblique Submucosa Mucosa

n Gastric pits and glands: n Contain cells n n n Surface mucous: Mucus Mucous neck: Mucus Parietal: Hydrochloric acid and intrinsic factor Chief: Pepsinogen Endocrine: Regulatory hormones

Secreción de HCl en células parietales

Barrera mucus – HCO 3

Fases de la secreción gástrica

FASE CEFÁLICA - percepción sensorial del alimento

FASE GÁSTRICA - presencia del alimento

Ondas de mezcla

FASE INTESTINAL VIP Gastrin

Duodeno y Pancreas

Pancreas n Anatomy n Endocrine n n Exocrine n n Pancreatic islets produce insulin and glucagon Acini produce digestive enzymes and HCO 3 - Regions: Head, body, tail n Secretions n Pancreatic juice (exocrine) n n n n Trypsin Chymotrypsin Carboxypeptidase Pancreatic amylase Pancreatic lipases Elastase Nucleases (DNA, RNA) HCO 3 -, H 20

Secreción de HCO 3 -

Enzimas n n n n Trypsinogen Chymotrysinogen Carboxypeptidases Pro-elastase Phospholipase pancreatic lipase Pancreatic amylase

Hígado n Lobes n n n Major: Left and right Minor: Caudate and quadrate Ducts n n Common hepatic Cystic n n From gallbladder Common bile n Joins pancreatic duct at hepatopancreatic ampulla

Histología del hígado triada portal Figure 24. 20 a, b

n Funciones del hígado Bile production n n Storage n n Glycogen, fat, vitamins, copper and iron Aminoacid synthesis Cholesterol and tryglicerid synthesis Gluconeogénesis, glucogenólisis n n Salts emulsify fats, contain pigments as bilirubin Hepatocytes remove ammonia and convert to urea Phagocytosis n Kupffer cells phagocytize worn-out and dying red and white blood cells, some bacteria Plasma proteins and hemostatic factors n Albumins, globulins, fibrinogen, heparin, K vitamin n Detoxification and drug metabolism n Hormonal secretion: trombopoietin, angotensinogen n

Bilis …each day around 600 ml of bile is produced… n n n n Bile acid Phospholipids Cholesterol Bilirubin Waste products Electrolytes Mucin HCO 3 -

Conductos

Intestino delgado n n Site of greatest amount of digestion and absorption Divisions n n Modifications n n Duodenum Jejunum Ileum: Peyer’s patches or lymph nodules Circular folds or plicae circulares, villi, lacteal, microvilli Cells of mucosa n Absorptive, goblet, granular, endocrine

Secreciones del int. delgado n Mucus and HCO 3 n n Enzymes n n n Protects against digestive enzymes and stomach acids Disaccharidases Peptidases Nucleotidases, nucleosidases Enteroquinase: tripsinógeno tripsina Duodenal glands (Brünner) n Stimulated by vagus nerve, secretin, chemical or tactile irritation of duodenal mucosa

Duodeno llegan: quimo ácido, jugos pancreáticos, bilis

Absorción intestinal

Monosacáridos

Lípidos

Lipoproteinas n Types n Chylomicrons n n n VLDL n n Enter lymph Transports cholesterol to cells HDL n Transports cholesterol from cells to liver

Intestino grueso n n n Extends from ileocecal junction to anus Consists of cecum, colon, rectum, anal canal Movements sluggish (18 -24 hours)

Intestino grueso: Absorción de H 2 O y Defecación Figure 21 -27: Anatomy of the large intestine

Large Intestine n Cecum n n Colon n n Ascending, transverse, descending, sigmoid Rectum n n Blind sac, vermiform appendix attached Straight muscular tube Anal canal n n Internal anal sphincter (smooth muscle) External anal sphincter (skeletal muscle)

Histology of Large Intestine

n n n Water and electrolyte secretion &/or absorption Bacterial fermentation of HC Bacterial synthesis of Vit. K , B. Bacterial degradation of bile acids and esterols Absortion of lactate & butyrate Prevents infections and immune alterations Figure 21 -28: Na. Cl reabsorption by colonocytes

Figure 21 -29: Na. Cl secretion by colonic crypt cells

Toxina colérica - ADP-ribosilación de Ga - G-GTP AC c. AMP PKA p-CFTR PKA

Secreciones n Mucus provides protection n n Parasympathetic stimulation increases rate of goblet cell secretion Pumps Exchange of bicarbonate ions for chloride ions n Exchange of sodium ions for hydrogen ions n n Bacterial actions produce gases called flatus

Reflejos en Colon y Recto

Secreciones del tubo digestivo

Enzimas del tubo digestivo

Regulación nerviosa y hormonal n Nervous regulation n Involves enteric nervous system n n Types of neurons: sensory, motor, interneurons Coordinates peristalsis and regulates local reflexes n Chemical regulation n Production of hormones n n Gastrin, secretin Production of paracrine chemicals n n Histamine Help local reflexes in ENS control digestive environments as p. H levels

Regulating Digestion: CNS and Enteric Nervous System (ENS) Figure 21 -9: The enteric nervous system

Hormonas gastrointestinales