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Digestive System AnatomyDigestive System Anatomy
Digestive tractDigestive tract Alimentary tract orAlimentary tract or
canalcanal
GI tractGI tract
Accessory organsAccessory organs Primarily glandsPrimarily glands
RegionsRegions Mouth or oral cavityMouth or oral cavity
PharynxPharynx
EsophagusEsophagus StomachStomach
Small intestineSmall intestine
Large intestineLarge intestine
AnusAnus
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Digestive Tract HistologyDigestive Tract Histology
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Digestive System RegulationDigestive System Regulation
Nervous regulationNervous regulation
Involves enteric nervousInvolves enteric nervous
systemsystem
Types of neurons: sensory,Types of neurons: sensory,motor, interneuronsmotor, interneurons
Coordinates peristalsisCoordinates peristalsis
and regulates localand regulates local
reflexesreflexes
Chemical regulationChemical regulation
Production of hormonesProduction of hormones
Gastrin, secretinGastrin, secretin
Production of paracrineProduction of paracrine
chemicalschemicals
HistamineHistamine
Help local reflexes in EN
SHelp local reflexes in EN
Scontrol digestivecontrol digestive
environments as pH levelsenvironments as pH levels
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Peritoneum and MesenteriesPeritoneum and Mesenteries
PeritoneumPeritoneum VisceralVisceral: Covers organs: Covers organs
ParietalParietal: Covers interior: Covers interior
surface of body wallsurface of body wall
RetroperitonealRetroperitoneal: Behind: Behindperitoneum as kidneys,peritoneum as kidneys,
pancreas, duodenumpancreas, duodenum
MesenteriesMesenteries
Routes which vessels andRoutes which vessels andnerves pass from body wall tonerves pass from body wall to
organsorgans
Greater omentumGreater omentum
Lesser omentumLesser omentum
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Oral CavityOral Cavity
Mouth or oral cavityMouth or oral cavity VestibuleVestibule: Space: Space
between lips or cheeksbetween lips or cheeksand alveolar processesand alveolar processes
Oral cavity properOral cavity proper
Lips (labia) andLips (labia) andcheekscheeks
PalatePalate: Oral cavity: Oral cavityroofroof Hard and softHard and soft
Palatine tonsilsPalatine tonsils TongueTongue: Involved in: Involved in
speech, taste,speech, taste,mastication,mastication,swallowingswallowing
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TeethTeeth
Two setsTwo sets
Primary, deciduous,Primary, deciduous,
milk: Childhoodmilk: Childhood
Permanent orPermanent or
secondary: Adult (32)secondary: Adult (32)
TypesTypes
Incisors, canine,Incisors, canine,
premolar and molarspremolar and molars
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Tooth structure:Tooth structure:
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Salivary GlandsSalivary Glands
Produce salivaProduce saliva
Prevents bacterialPrevents bacterial
infectioninfection
LubricationLubrication
Contains salivaryContains salivary
amylaseamylase
Breaks down starchBreaks down starch
Three pairsThree pairs
Parotid: LargestParotid: Largest
SubmandibularSubmandibular
Sublingual: SmallestSublingual: Smallest
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Pharynx and EsophagusPharynx and Esophagus
PharynxPharynx
NasopharynxNasopharynx
Oropharynx: TransmitsOropharynx: Transmitsfood normallyfood normally
Laryngopharynx:Laryngopharynx:
Transmits foodTransmits food
normallynormally
EsophagusEsophagus
Transports food fromTransports food frompharynx to stomachpharynx to stomach
Passes through esophagealPasses through esophageal
hiatus (opening) ofhiatus (opening) ofdiaphragm and ends atdiaphragm and ends atstomachstomach Hiatal herniaHiatal hernia
SphinctersSphincters UpperUpper
LowerLower
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Deglutition (Swallowing)Deglutition (Swallowing)
Three phasesThree phases
VoluntaryVoluntary
Bolus of food moved by tongue from oral cavity toBolus of food moved by tongue from oral cavity to
pharynxpharynx PharyngealPharyngeal
ReflexReflex: Upper esophageal sphincter relaxes, elevated: Upper esophageal sphincter relaxes, elevatedpharynx opens the esophagus, food pushed intopharynx opens the esophagus, food pushed intoesophagusesophagus
EsophagealEsophageal
ReflexReflex: Epiglottis is tipped posteriorly, larynx elevated: Epiglottis is tipped posteriorly, larynx elevatedto prevent food from passing into larynxto prevent food from passing into larynx
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Phases of DeglutitionPhases of Deglutition
(Swallowing)(Swallowing)
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FunctionsFunctions
IngestionIngestion: Introduction of food into stomach: Introduction of food into stomach MasticationMastication: Chewing: Chewing
PropulsionPropulsion
Deglutition: SwallowingDeglutition: Swallowing
Peristalsis: Moves material through digestive tractPeristalsis: Moves material through digestive tract
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Stomach Anatomy:Stomach Anatomy:
OpeningsOpenings GastroesophagealGastroesophageal::
To esophagusTo esophagus
PyloricPyloric: To: To
duodenumduodenum RegionsRegions
CardiacCardiac
FundusFundus
BodyBody
PyloricPyloric
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Stomach Histology:Stomach Histology:
LayersLayers
Serosa or visceralSerosa or visceral
peritoneum:peritoneum:
OutermostOutermost
Muscularis: ThreeMuscularis: Threelayerslayers
Outer longitudinalOuter longitudinal
Middle circularMiddle circular
Inner obliqueInner oblique SubmucosaSubmucosa
MucosaMucosa
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Stomach HistologyStomach Histology
RugaeRugae: Folds in: Folds instomach when emptystomach when empty
Gastric pitsGastric pits: Openings: Openingsfor gastric glandsfor gastric glands
Contain cellsContain cells Surface mucous: MucusSurface mucous: Mucus
Mucous neck: MucusMucous neck: Mucus
Parietal: HydrochloricParietal: Hydrochloricacid and intrinsic factoracid and intrinsic factor
Chief: PepsinogenChief: Pepsinogen
Endocrine: RegulatoryEndocrine: Regulatoryhormoneshormones
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Hydrochloric Acid ProductionHydrochloric Acid Production
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Phases of GastricPhases of Gastric
SecretionSecretion
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Movements in StomachMovements in Stomach
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Small IntestineSmall Intestine
Site of greatest amount ofSite of greatest amount ofdigestion and absorptiondigestion and absorption
DivisionsDivisions DuodenumDuodenum
JejunumJejunum
Ileum: Peyers patches orIleum: Peyers patches orlymph noduleslymph nodules
ModificationsModifications Circular folds or plicaeCircular folds or plicae
circulares, villi, lacteal,circulares, villi, lacteal,
microvillimicrovilli Cells of mucosaCells of mucosa
Absorptive, goblet, granular,Absorptive, goblet, granular,endocrineendocrine
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Small Intestine SecretionsSmall Intestine Secretions
MucusMucus Protects against digestive enzymes and stomach acidsProtects against digestive enzymes and stomach acids
Digestive enzymesDigestive enzymes Disaccharidases: Break down disaccharides toDisaccharidases: Break down disaccharides to
monosaccharidesmonosaccharides
Peptidases: Hydrolyze peptide bondsPeptidases: Hydrolyze peptide bonds
Nucleases: Break down nucleic acidsNucleases: Break down nucleic acids
Duodenal glandsDuodenal glands Stimulated by vagus nerve, secretin, chemical or tactileStimulated by vagus nerve, secretin, chemical or tactile
irritation of duodenal mucosairritation of duodenal mucosa
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Duodenum and PancreasDuodenum and Pancreas
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Duodenum Anatomy andDuodenum Anatomy and
HistologyHistology
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LiverLiver
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 atJoins pancreatic duct at
hepatopancreatic ampullahepatopancreatic ampulla
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Functions of the LiverFunctions of the Liver
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
Nutrient interconversionNutrient interconversion
DetoxificationDetoxification Hepatocytes remove ammonia and convert to ureaHepatocytes remove ammonia and convert to urea
PhagocytosisPhagocytosis Kupffer cells phagocytize wornKupffer cells phagocytize worn--out and dying red and white blood cells,out and dying red and white blood cells,
some bacteriasome bacteria
SynthesisSynthesis Albumins, fibrinogen, globulins, heparin, clotting factorsAlbumins, fibrinogen, globulins, heparin, clotting factors
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Blood and Bile FlowBlood and Bile Flow
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Duct SystemDuct System
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GallbladderGallbladder
Bile is stored and concentratedBile is stored and concentrated
Stimulated by cholecystokinin and vegalStimulated by cholecystokinin and vegal
stimulationstimulation Dumps into small intestineDumps into small intestine
Production of gallstones possibleProduction of gallstones possible
Drastic dieting with rapid weight lossDrastic dieting with rapid weight loss
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PancreasPancreas
AnatomyAnatomy
EndocrineEndocrine
Pancreatic islets producePancreatic islets produce
insulin and glucagoninsulin and glucagon ExocrineExocrine
Acini produce digestiveAcini produce digestive
enzymesenzymes
RegionsRegions: Head, body, tail: Head, body, tail
SecretionsSecretions
Pancreatic juice (exocrine)Pancreatic juice (exocrine) TrypsinTrypsin
ChymotrypsinChymotrypsin
CarboxypeptidaseCarboxypeptidase
Pancreatic amylasePancreatic amylase
Pancreatic lipasesPancreatic lipases
Enzymes that reduce DNAEnzymes that reduce DNAand ribonucleic acidand ribonucleic acid
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Bicarbonate Ion ProductionBicarbonate Ion Production
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Gastric hormones:Gastric hormones:
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Movement in small intestine:Movement in small intestine:
Mixing: Segmental contraction that occurs in small intestineMixing: Segmental contraction that occurs in small intestine Secretion: Lubricate, liquefy, digestSecretion: Lubricate, liquefy, digest
Digestion: Mechanical and chemicalDigestion: Mechanical and chemical
Absorption: Movement from tract into circulation or lymphAbsorption: Movement from tract into circulation or lymph
Elimination: Waste products removed from bodyElimination: Waste products removed from body
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Large Intestine:Large Intestine:
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 (1818--24 hours24 hours))
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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)
Hemorrhoids: Vein enlargement or inflammationHemorrhoids: Vein enlargement or inflammation
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Secretions ofLarge IntestineSecretions ofLarge Intestine
Mucus provides protectionMucus provides protection
Parasympathetic stimulation increases rate of gobletParasympathetic stimulation increases rate of goblet
cell secretioncell secretion
PumpsPumps
Exchange of bicarbonate ions for chloride ionsExchange of bicarbonate ions for chloride ions
Exchange of sodium ions for hydrogen ionsExchange of sodium ions for hydrogen ions
Bacterial actions produce gases called flatusBacterial actions produce gases called flatus
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Histology ofLarge IntestineHistology ofLarge Intestine
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Movement in Large IntestineMovement in Large Intestine
Mass movementsMass movements Common after mealsCommon after meals
Local reflexesLocal reflexes in enteric plexusin enteric plexus
GastrocolicGastrocolic: Initiated by stomach: Initiated by stomach DuodenocolicDuodenocolic: Initiated by duodenum: Initiated by duodenum
Defecation reflexDefecation reflex Distension of the rectal wall by fecesDistension of the rectal wall by feces
DefecationDefecation Usually accompanied by voluntary movements to expel fecesUsually accompanied by voluntary movements to expel feces
through abdominal cavity pressure caused by inspirationthrough abdominal cavity pressure caused by inspiration
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Reflexes inReflexes in
Colon andColon andRectum:Rectum:
Di ti Ab tiDi ti Ab ti
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Digestion, Absorption,Digestion, Absorption,
TransportTransport
DigestionDigestion
Breakdown of food molecules for absorption intoBreakdown of food molecules for absorption into
circulationcirculation
MechanicalMechanical: Breaks large food particles to small: Breaks large food particles to small
ChemicalChemical: Breaking of covalent bonds by digestive: Breaking of covalent bonds by digestive
enzymesenzymes
AbsorptionAbsorption andand transporttransport Molecules are moved out of digestive tract and intoMolecules are moved out of digestive tract and into
circulation for distribution throughout bodycirculation for distribution throughout body
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Figure 24.20a, b
Liver HistologyLiver Histology
portal
triad
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3. Architecture of the Hepatic3. Architecture of the Hepatic
ParenchymaParenchymaThe hepatic lobuleThe hepatic lobule is the structural unit of the liver.is the structural unit of the liver.
Central vein
Portal vein
Bile duct
Sinusoids
Liver cells (Hepatocytes)
Hepatic arteryP
ortal area
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BileBile
Bile acidBile acid
PhospholipidsPhospholipids CholesterolCholesterol
BilirubinBilirubin
Waste productsWaste products
ElectrolytesElectrolytes
MucinMucin
each day around 600 ml of bile is produced
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Functions of the LiverFunctions of the Liver
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
Nutrient interconversionNutrient interconversion
DetoxificationDetoxification Hepatocytes remove ammonia and convert to ureaHepatocytes remove ammonia and convert to urea
PhagocytosisPhagocytosis Kupffer cells phagocytize wornKupffer cells phagocytize worn--out and dying red and white blood cells,out and dying red and white blood cells,
some bacteriasome bacteria
SynthesisSynthesis Albumins, fibrinogen, globulins, heparin, clotting factorsAlbumins, fibrinogen, globulins, heparin, clotting factors
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Exocrine PancreasExocrine PancreasEnzymesEnzymes
TrypsinogenTrypsinogen
ChymotrysinogenChymotrysinogen
CarboxypeptidasesCarboxypeptidases
ProPro--elastaseelastase
PhospholipasePhospholipase
pancreatic lipasepancreatic lipase
Pancreatic amylasePancreatic amylase
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Bicarbonate Ion ProductionBicarbonate Ion Production
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LipoproteinsLipoproteins
TypesTypes
ChylomicronsChylomicrons
Enter lymphEnter lymph
VLDLVLDL
LDLLDL
Transports cholesterolTransports cholesterol
to cellsto cells
HDLHDL Transports cholesterolTransports cholesterol
from cells to liverfrom cells to liver
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W d IW d I
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Water and Ions:Water and Ions:
WaterWater
Can move in either directionCan move in either direction
across wall of small intestineacross wall of small intestine
depending on osmoticdepending on osmotic
gradientsgradients
IonsIons
Sodium, potassium, calcium,Sodium, potassium, calcium,
magnesium, phosphate aremagnesium, phosphate are
actively transportedactively transported
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Effects of AgingEffects of Aging
Decrease in mucus layer, connective tissue,Decrease in mucus layer, connective tissue,
muscles and secretionsmuscles and secretions
Increased susceptibility to infections and toxicIncreased susceptibility to infections and toxicagentsagents
Ulcerations and cancersUlcerations and cancers
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