Lecture Digestive Anatomy & Physiology Digestive Anatomy ...
THE DIGESTIVE SYSTEM II D. C. Mikulecky Professor of Physiology Virginia Commonwealth University.
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Transcript of THE DIGESTIVE SYSTEM II D. C. Mikulecky Professor of Physiology Virginia Commonwealth University.
PANCREATIC SECRETIONS
THE PANCREAS IS BOTH ENDOCRINE AND EXOCRINE
THE EXOCRINE PANCREAS SECRETES DIGESTIVE ENZYMES AND AN AQUEOUS ALKALINE FLUID
PANCREATIC SECRETION IS HORMONALLY REGULATED
PANCREATIC SECRETIONS REACH THE SMALL INTESTINE VIA THE COMMON BILE DUCT
THE ENDOCRINE PANCREAS
INSULIN AND GLUCAGON
IMPORTANT IN THE CONTROL OF GLUCOSE, FAT AND PROTEIN METABOLISM
ACT IN OPPOSITE WAYS
AQUEOUS COMPONENT OF PANCREATIC SECRETION
COMPOSITION CHANGES WITH SECRETION RATE (TRANSIT TIME)
DUCTILE CELLS SECRETE BICARBONATE AND WATER
CHLORIDE AND BICARBONATE VARY RECIPROCALLY
SODIUM AND POTASSIUM ARE LIKE IN PLASMA
HORMONAL CONTROL OF PANCREATIC SECRETION
ACID IN DUODENAL LUMEN >SECRETIN: STIMULATES PANCREATIC DUCT CELLS TO PRODUCE SIGNIFICANT QUANTITES OF AQUEOUS ALKALINE SECRETION
FAT AND PROTEIN IN DUODENAL LUMEN>CHOLECYSTOKININ (CCK):STIMULATES PANCREATIC ACINAR CELLS TO SECRETE DIGESTIVE ENZYMES
SECRETIN
ENDOCRINE CELLS IN DUODENAL MUCOSA ACID IN DUODENAL LUMEN INHIBITS GASTRIC EMPTYING INHIBITS GASTRIC SECRETION STIMULATES AQUEOUS BICARBONATE
SECRETION BY PANCREAS STIMULATES BICARBONATE RICH BILE
SECRETION BYLIVER
CHOLECYSTOKININ
ENDOCRINE CELLS IN DUODENAL MUCOSA FAT AND PROTEIN IN DUODENAL LUMEN INHIBITS GASTRIC EMPTYING INHIBITS GASTRIC SECRETION CAUSES GALL BLADDER CONTRACTION CAUSES RELAXATION OF THE SPHINCTER OF
ODDI CONTRIBUTES TO SATIETY
FUNCTIONS OF THE LIVER
METABILIC PROCESSING OF ABSORBED FOOD
DETOXIFICATION2SYNTHESIS OF PLASMA PROTEINSSTORAGE OF GLYCOGEN AND FAT, ETC.REMOVAL OF BACTERIA AND WORN-OUT
RBCEXCRETION OF CHOLESTEROL AND
BILIRUBIN
BILE SECRETION, STORAGE, AND CIRCULATION
SECRETED BY THE LIVERRECYCLED THROUGH
ENTEROHEPATIC CIRCULATIONSTORED IN GALL BLADDER
LIVER BLOOD FLOW
HEART
LIVER
STOMACHANDSMALLINTESTINE
HEPATICPORTALVEIN
HEPATICVEIN
INFERIORVENA CAVA AORTA
HEPATICARTERY
ARTERIES TODIGESTIVE TRACT
SEGMENTATION CONTRACTIONS
INITIATED BY PACEMAKER CELLSMIXING ACTIONMOVES CHYME DOWNWARDILEOCECAL VALVE
MAINLY IN THE SMALL INTESTINE
SALIVARY AMYLASE
ACID AND PEPSIN IN THE STOMACH
ENZYMES COME FROM PANCREAS
PANCREATIC ENZYMES
PROTEOLYTIC: BREAK PROTEINS DOWN TO SMALLER PEPTIDE FRAGMENTS AND/OR AMINO ACIDS
PANCREATIC AMYLASE BREAKS STARCH DOWN TO OLIGOSACHHARIDES AND DISACCHARIDES
PANCREATIC LIPASE, PHOSPHOLIPASE AND OTHERS
OTHERS
ENZYME PRECURSORS ARE A WAY OF PROTECTING THE GUT FROM SELF-DIGESTION
PEPSIN IN THE SOMACH AND PROTEOLYTIC ENZYMES IN THEM PANCREAS
SECRETED IN AN INACTIVE FORM, LONGER MOLECULE
REMOVAL OF A SEGMENT ACTIVATES THEM
BRUSH BORDER ENZYMES
CARBOHYDRATES: DISACCARIDASES IN BRUSH BORDER MEMBRANE FINISH THE JOB
PROTEINS: ALSO POLY AND DI-PEPTIDASES
TRANSPORT SYSTEMS ARE NEAR-LESSENS THE OSMOTIC EFFECT?
ABSORPTION: THE SMALL INTESTINE IS THE ABSORBING ORGAN
LARGE SURFACE AREAACTIVE SODIUM TRANSPORTFLUID AND ELECTROLYTESSUGARS AND AA BY SECONDARY
ACTIVE TRANSPORTFATVITAMINS AND MINERALS
FLUID AND ELECTROLYTE ABSORPTION IS BY A SPECIAL PROCESS: ISOTONIC TRANSPORT
THE WHOLE TISSUE (SODIUM TRANSPORTING EPITHELIUM) IS INVOLVED
SODIUM/POTASSIUM ATPASE PUMPS ONLY ON BASOLATERAL CELL MEMBRANES
TIGHT JUNCTIONS VS LOOSE SEROSAL SIDE (6-PACK ANALOGY)
A Network Model of Coupled Salt and Volume Flow Through an Epithelium
AM TJ
BM
BL
CL PL
CB PB
CELL
LUMEN
BLOOD
THE CURRAN-MACINTOSH MODEL
A B C
FLUID MOVESR ---> L
HYPERTONIC FLUID
INJECTED
MEMBRANES: TIGHT LOOSE
SOURCES OF WATER AND ELECTROLYTES IN GUT(ML/DAY), EXCLUDING INTESTINAL
SECRETIONS
IMBIBED: 2,000 SECRETIONS:
SALIVA 1,500GASTRIC JUICE 2,000PANCREATIC JUICE 1,500BILE 500INTESTINAL 1,500
-----------------------------------------------------------TOTAL: SECRETED + IMBIBED 9,000