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DIGESTIVE SYSTEM

DIGESTIVE SYSTEM. FUNCTION??. MAKE FOOD SMALL ENOUGH TO BE ABSORBED MONOMERS. DIGESTIVE SYSTEM. kidshealth.org. DIGESTIVE SYSTEM. www.nlm.nih.gov. DIGESTIVE SYSTEM. arbl.cvmbs.colostate.edu. MICROANATOMY OF THE DIGESTIVE TUBE. arbl.cvmbs.colostate.edu. MUCOSA.

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DIGESTIVE SYSTEM

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  1. DIGESTIVE SYSTEM

  2. FUNCTION?? • MAKE FOOD SMALL ENOUGH TO BE ABSORBED • MONOMERS

  3. DIGESTIVE SYSTEM kidshealth.org

  4. DIGESTIVE SYSTEM www.nlm.nih.gov

  5. DIGESTIVE SYSTEM arbl.cvmbs.colostate.edu

  6. MICROANATOMY OF THEDIGESTIVE TUBE arbl.cvmbs.colostate.edu

  7. MUCOSA • SURFACE EPITHELIUM; CONNECTIVE TISSUE; SMOOTH MUSCLE; SOME HAVE FOLDINGS TO ?; TUBULAR GLANDS: • MUCUS; DIGESTIVE ENZYMES • LUMEN • PROTECTS LAYERS & BODY; SECRETION AND ABSORPTION

  8. SUBMUCOSA • LOOSE CONNECTIVE TISSUE; GLANDS; BLOOD VESSELS; LYMPH VESSELS; NERVES; • TO NOURISH AND TRANSPORT MATERIAL AWAY

  9. MUSCULAR LAYER • INNER COAT: CIRCULAR SMOOTH MUSCLE FIBERS: DIAMETER DECREASES • OUTER COAT: LONGITUDINAL FIBERS: TUBE SHORTENS • FOR MOVEMENTS

  10. SEROSA/SEROUS LAYER • OUTER COVERING: VISCERAL PERITONEUM; CONNECTIVE TISSUE WITH EPITHELIUM ON TOP (OUTSIDE); • PROTECT TISSUES BELOW; SECRETE SEROUS FLUID: MOISTENS AND LUBRICATES SO ORGANS SLIDE FREELY

  11. MUCOSAL EPITHELIUM arbl.cvmbs.colostate.edu

  12. MOVEMENTS • MIXING: • MOVEMENT OF STOMACH, OR SEGMENTS (SEGMENTATION); MIXES FOOD AND DIGESTIVE ENZYMES • PROPELLING: • PERISTALSIS: RING OF CONTRACTION & CAUSES RECEPTIVE RELAXATION

  13. SEGMENTATION arbl.cvmbs.colostate.edu

  14. PERISTALSIS arbl.cvmbs.colostate.edu

  15. PERISTALSIS www.nlm.nih.gov

  16. INNERVATION • USUALLY WHICH ONE ? • PARASYMPATHETIC • BY PLEXUSES ? • INCREASE ACTIVITY; VAGUS NERVE & SACRAL POTION OF S.C. • SYMPATHETIC • DECREASE • FIGHT OR FLIGHT

  17. MOUTH • CHEEK & LIPS: SKELETAL MUSCLES • TONGUE: • LINGUAL FRENULUM: TO FLOOR • PAPILLAE • FRICTION, TASTE BUDS • HYOID BONE • LINGUAL TONSILS: OF WHICH SYSTEM?

  18. PALATE • ANTERIOR: HARD • POSTERIOR: SOFT • UVULA • SWALLOWING: CLOSE NASAL PASSAGES • PALATINE TONSILS • PHARYNGEAL TONSILS: ADENOIDS

  19. TEETH • HARDEST STRUCTURES OF BODY • NOT BONE ? • PRIMARY: 10; 6 Mo TO 4y • SECONDARY: 32; 6 y TO 22y • FUNCTION: ? WHY? • INCISORS: BITE • CANINES: GRAB AND TEAR • PREMOLARS, MOLARS: GRINDING

  20. TEETH en.wikipedia.org

  21. CROWN • ENAMEL: CALCIUM; HARDEST SUBSTANCE; NOT REPLACED, WEARS DOWN • ROOT • DENTIN: HARDER THAN BONE • CENTRAL CAVITY: PULP • BLOOD VESSELS, NERVES, CONNECTIVE TISSUE • ROOT CANALS: CEMENTUM AROUND ROOT • PERIDONTAL LIGAMENT: COLLAGEN; CEMENTUM TO JAW

  22. SALIVARY GLANDS • PRODUCE ? FOR? • MOISTENS, BINDS, STARTS CHEMICAL DIGESTION OF FOOD; SOLVENT: DISSOLVES FOOD = TASTE; BICARBONATE IONS: BUFFER: BALANCE pH FOR ENZYME ACTION; 3 PAIR AND MANY MINOR GLANDS • 3 PAIR AND MANY MINOR GLANDS • SEROUS GLANDS • SALIVARY AMYLASE • STARCH AND GLYCOGEN • MUCOUS GLANDS • BINDS; LUBRICATES

  23. SALIVARY CONTROL • PARASYMPATHETIC • LARGE AMOUNT OT WATERY SALIVA • REFLEX: PAVLOV’S DOGS • SYMPATHETIC • SMALL AMOUNT OF VISCOUS SALIVA • UNPLEASANT LOOK, TASTE, SMELL • LESS SALIVA= HARD TO SWALLOW WHY?

  24. SALIVARY GLANDS www.entassociates.com

  25. MAJOR SALIVARY GLANDS • PAROTID • LARGEST; CLEAR WATERY; LOTS OF AMYLASE • SUBMANDIBULAR • EQUALLY SEROUS AND MUCOUS • SUBLINGUAL • SMALLEST OF 3 • MOSTLY MUCOUS

  26. PHARYNX • CONNECT NASAL AND ORAL CAVITY TO LARYNX AND ESOPHAGUS • NASOPHARYNX • BEHIND SOFT PALATE • AIR PASSAGEWAY • EUSTACHIAN CANAL OPENING • OROPHARYNX • END OF MOUTH TO EPIGLOTTIS • LARYNGOPHARYNX • EPIGLOTTIS TO LARYNX

  27. PHARYNX 1) Nasopharynx 2) Nasal Septum 3) Hard Palate 4) Tongue 5) Oropharynx 6) Laryngopharynx anatomy.med.umich.edu

  28. CIRCULAR MUSCLES= CONSTRICTOR MUSCLES • SUPERIOR; MIDDLE; INFERIOR • SOME OF INFERIOR CONSTRICTOR MUSCLES ARE USUALLY CONTRACTED TO KEEP AIR OUT OF ESOPHAGUS • SKELETAL MUSCLES BUT MOSTLY A REFLEX

  29. SWALLOWING STEPS • 1: VOLUNTARY; CHEWING AND TURNING FOOD INTO BOLUS; TONGUE FORCES TO PHARYNX • 2: SWALLOWING REFLEX STIMULATED • SOFT PALATE RAISES ? • EPIGLOTTIS BLOCKS TRACHEA ? • TONGUE PRESSES ON SOFT PALATE ? • LONGITUDINAL MUSCLES CONTSTRICT ? • INFERIOR CONSTRICTOR MUSCLE RELAXES ? • SUPERIOR CONSTRICTOR MUSCLE CONTRACTS • 3: PERISTALSIS: FOOD THROUGH ESOPHAGUS TO STOMACH

  30. ESOPHAGUS • 25 CM; COLLAPSIBLE ?; WHICH STATE (COLLAPSED/UNCOLLAPSED) USUALLY? WHY? • HOW DOES FOOD GET TO ABDOMEN ? • HIATUS • MUCOUS GLANDS ? • LOWER ESOPHAGEAL SPHINCTER ? • USUALLY CLOSED ? • PERISTALSIS OPENS SPHINCTER ?

  31. STOMACH • 25-30 CM; CAVITY ~ 1L; RUGAE ? • JUST BELOW DIAPHRAGM • TYPE OF DIGESTION ? • BOTH; • MIXES FOOD WITH GASTRIC JUICE; STARTS PROTEIN DIGESTION; SOME ABSORPTION; FOOD TO INTESTINES • REGULAR 2 SMOOTH MUSCLE LAYERS: PLUS OBLIQUE MUSCLES (ESPECIALLY FUNDUS AND BODY); • STRONGER; MORE MIXING

  32. PARTS • CARDIA: NEAR ESOPHAGEAL OPENING • FUNDUS: BALLOON AREA AT START: STORAGE • BODY: DILATED AREA; MIDDLE; • PYLORIC ANTRUM: FUNNEL SHAPED; AT END TO ? • PYLORIC CANAL: BEFORE SMALL INTESTINE • PYLORIC SPHNCTER: THICK CIRCULAR MUSCLE; VALVE: CONTROLS EMPTYING

  33. GASTRIC SECRETIONS • GASTRIC PITS: GASTRIC GLANDS: TUBULAR: OR 3 SECTRETORY CELL TYPES • MUCOUS: NEAR OPEININGS OF PITS; • CHIEF CELLS: DEEPER; DIGESTIVE ENZYMES • PARIETAL CELLS: DEEPER; HCl • ALL= GASTRIC JUICE • CHIEF CELLS RELEASE PEPSINOGEN: INACTIVE FORM OF PEPSIN WHY INACTIVE? • PEPSINOGEN AND HCl= PEPSIN • GASTRIC LIPASE: MOSTLY ON BUTTERFAT BECAUSE OF LOW pH

  34. MUCUS PROTECTS FROM PEPSIN • PARIETAL CELLS ALSO SECRETE INTRINSIC FACTOR: HELPS ABSORB VITAMIN B12

  35. CONTROL OF GASTRIC SECRETIONS • PRODUCED CONTIUOUSLY BUT IN VARYING AMOUNTS • CELLS OF GASTRIC GLANDS SECRETE SOMATOSTATIN: INHIBITS ACID SECRETION • PARASYMPATHETIC: ACh SUPRESSES SOMATOSTATIN AND MORE GASTRIC JUICE PRODUCED • GASTRIN ALSO INCREASES SECRETION • CAUSE HISTAMINE TO BE RELEASED= INCREASES GASTRIC SECRETION

  36. THREE STAGES • CEPHALIC PHASE: • BEFORE FOOD ENTERS STOMACH: SMALL, TASTE, LOOK, THOUGHT OF FOOD BY PARASYMPATHETIC STIMULATION • GREATER HUNGER = GREATER SECRETION • 30-50% OF SECRETION • GASTRIC PHASE: • 40-50%; WHEN FOOD ENTERS STOMACH • DISTENSION OF STOMACH = RELEASE OF GASTRIN = PRODUCTION OF MORE GASTRIC SECRETION • pH AT 3.0 = GASTRIN INHIBITED; 1.5 = GASTRIC SECRETION STOPS • H+ FOR HCl COMES FROM BLOOD REPLACED BY BICARBONATE ION

  37. INTESTINAL PHASE: • 5%; WHEN FOOD ENTERS SMALL INTESTINES RELEASES INTESTINAL GASTRIN FROM INTESTINES • MORE FOOD ENTERS SMALL INTESTINES AND SYMPATHETIC IMPULSES = INHIBITS SECRETION • PROTEIN AND FAT RELEASES CHOLECYSTOKININ WHICH SLOWS MIXING OF STOMACH • FATS CAUSE RELEASE OF INTESTINAL SOMATOSTATIN WHICH DECREASES GASTRIC SECRETION

  38. GASTRIC ABSORPTION • A LITTLE BIT • WATER, SOME SALTS, SOME LIPID-SOLUBLE DRUGS, ALCOHOL

  39. MIXING/EMPTYING • STOMACHACHE FROM TOO MUCH FOOD • MIXING: BOLUSCHYME • PERISTALSIS SLOWLY MOVES CHYME INTO SMALL INTESTINES • PASSING THROUGH DEPENDS ON TYPE OF FOOD: FATS UP TO 6 HOURS • AS FOOD ENTERS SMALL INTESTINES THE PRESSURE BUILDS UP AND ENTEROGASTRIC REFLEX INHIBITS STOMACH PERISTALSIS AND SLOWS INTESTINAL FILLING • CHOLECYSTOKININ RELEASED TO DECREASE PERISTALSIS

  40. VOMITTING: REVERSE PERISTALSIS BY VOMITTING CENTER OF MEDULLA CONTRACTS ON STOMACH TO EXPELL STOMACH

  41. PANCREAS • DUCT TO DUODENUM • CELLS: • PANCREATIC ACINAR CELLS

  42. PANCREATIC JUICE • PANCREATIC ACINAR CELLS: • PANCREATIC AMYLASE: ? • PANCREATIC LIPASE: ? • TRYPSIN, CHYMOTRYPSIN, CARBOXYPEPTIDASE: SPECIFIC PEPTIDE BONDS • STORED AND RELEASED IN INACTIVE FORMS ? • TRYPSINOGEN ACTIVATED BY ENTEROKINASE THEN TRYPSIN ACTIVATES THE OTHER 2 NUCLEASES: ? BICARBONATE: ALKALINE; NEUTRALIZES HCl

  43. CONTROL OF SECRETION • NERVOUS AND ENDOCRINE SYSTEMS • DURING CEPHALIC AND GASTRIC PHASES PARASYMPATHETIC STIMULATES PANCREAS • SECRETIN STIMULATES RELEASE WHEN CHYME ENTERS DUODENUM: MOST;LY BICARBONATE IONS • PROTEIN & FAT STIMULATES RELEASE OF CHOLECYSTOKININ STIMULATES SECRETION

  44. LIVER • FIBROUS CAPSULE; TWO MAJOR LOBES; TWO MINOR LOBES • HEPATIC LOBULES: FUNCTIONAL UNIT • HEPATIC CELLS; HEPATIC SINUSOIDS; • KUPFFER CELLS: REMOVE BACTERIA • COMMON HEPATIC DUCT

  45. FUNCTIONS: • CARBOHYDRATE METABOLISM, GLYCOGEN; GLUCONEOGENESIS; OXIDIZING FATTY ACIDS; SYNTHESIS OF MOLECULES; DEAMINATION OF AMINO ACIDS, FORMATION OF UREA AND OTHER AMINO ACIDS; STORAGE: GLYCOGEN, IRON, VITAMINS A, D, B12; DESTROY DAMAGED RBCs; REMOVES TOXIC MATERIAL; PHAGOCYTIZE PATHOGENS; BLOOD RESERVOIR; SECRETES BILE

  46. BILE • COMPOSITION: WATER, BILE SALTS, BILE PIGMENTS, CHOLESTEROL, ELECTROLYTES

  47. GALL BLADDER • DEPRESSION IN LIVER • STORES, CONCENTRATES AND RELEASES BILE • RELEASED WHEN STIMULATED BY CHOLECYSTOKININ • RELEASED THROUGH BILE DUCT TO HEPATOPANCREATIC SPHINCTER • CHOLESTEROL COULD FORM GALL STONES

  48. BILE SALT FUNCTION • EMULSIFICATION • AIDS LIPASE • AIDS ABSORBTION • FATTY ACIDS, GLYCEROL, & FAT SOLUBLE VITAMINS: A, D, E, K MOST OF BILE SALTS ARE REABSORBED IN SMALL INTESTINES

  49. SMALL INTESTINE • 9-10 FT LONG • RECEIVES DIGESTIVE ENZYMES FROM LIVER AND PANCREAS; FINISHES CHEMICAL DIGESTION; ABSORBTION; MOVES MATERIAL TO LARGE INTESTINES

  50. PARTS • DUODENUM: • SHORTEST (25cm); MOST FIXED; • JEJUNUM: • PROXIMAL 2/5THS; MOBILE • ILEUM: • REST; MOBILE; USUALLY NO DISTINCT BREAK BUT JEJUNUM HAS LARGER DIAMETER; THICKER WALL, MORE ACTIVE, MORE VASCULAR, MORE LYMPH MATERIAL HELD BY MESENTERY

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