digestive system anatomy
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Digestive System Digestive System AnatomyAnatomy
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
FunctionsFunctions IngestionIngestion: Introduction of food into stomach: Introduction of food into stomach MasticationMastication: Chewing: Chewing PropulsionPropulsion
Deglutition: SwallowingDeglutition: Swallowing Peristalsis: Moves material through digestive Peristalsis: Moves material through digestive
tracttract
Digestive Tract Digestive Tract HistologyHistology
Digestive System Digestive System RegulationRegulation
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
Peritoneum and Peritoneum and MesenteriesMesenteries
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
Oral CavityOral Cavity 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
TeethTeeth
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
Tooth structure:Tooth structure:
Salivary GlandsSalivary Glands 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
Pharynx and EsophagusPharynx and Esophagus
PharynxPharynx NasopharynxNasopharynx Oropharynx: Oropharynx:
Transmits food Transmits food normallynormally
Laryngopharynx: Laryngopharynx: Transmits food Transmits food normallynormally
EsophagusEsophagus Transports food from Transports food from
pharynx to stomachpharynx to stomach Passes through Passes through
esophageal hiatus esophageal hiatus (opening) of (opening) of diaphragm and ends diaphragm and ends at stomachat stomach
Hiatal herniaHiatal hernia SphinctersSphincters
UpperUpper LowerLower
Deglutition Deglutition (Swallowing)(Swallowing)
Three phasesThree phases VoluntaryVoluntary
Bolus of food moved by tongue from oral Bolus of food moved by tongue from oral cavity to pharynxcavity to pharynx
PharyngealPharyngealReflexReflex: Upper esophageal sphincter : Upper esophageal sphincter
relaxes, elevated pharynx opens the relaxes, elevated pharynx opens the esophagus, food pushed into esophagusesophagus, food pushed into esophagus
EsophagealEsophageal ReflexReflex: Epiglottis is tipped posteriorly, : Epiglottis is tipped posteriorly,
larynx elevated to prevent food from larynx elevated to prevent food from passing into larynxpassing into larynx
Phases of Deglutition Phases of Deglutition (Swallowing)(Swallowing)
Stomach Anatomy:Stomach Anatomy:
OpeningsOpenings GastroesophaGastroesopha
gealgeal: To : To esophagusesophagus
PyloricPyloric: To : To duodenumduodenum
RegionsRegions CardiacCardiac FundusFundus BodyBody PyloricPyloric
Stomach Histology:Stomach Histology: 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
Stomach HistologyStomach Histology RugaeRugae: Folds in : Folds in
stomach when emptystomach when empty Gastric pitsGastric pits: :
Openings for gastric Openings for gastric glandsglands Contain cellsContain cells
Surface mucous: Surface mucous: MucusMucus
Mucous neck: Mucus Mucous neck: Mucus Parietal: Hydrochloric Parietal: Hydrochloric
acid and intrinsic acid and intrinsic factor factor
Chief: Pepsinogen Chief: Pepsinogen Endocrine: Regulatory Endocrine: Regulatory
hormoneshormones
Hydrochloric Acid Hydrochloric Acid ProductionProduction
Movements in StomachMovements in Stomach
Phases of Gastric Phases of Gastric SecretionSecretion
Small IntestineSmall Intestine 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
Small Intestine Small Intestine SecretionsSecretions
MucusMucus Protects against digestive enzymes and Protects against digestive enzymes and
stomach acidsstomach acids Digestive enzymesDigestive enzymes
Disaccharidases: Break down disaccharides Disaccharidases: Break down disaccharides to monosaccharidesto monosaccharides
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 Stimulated by vagus nerve, secretin, chemical
or tactile irritation of duodenal mucosaor tactile irritation of duodenal mucosa
Duodenum and Duodenum and PancreasPancreas
Duodenum Anatomy Duodenum Anatomy and Histologyand Histology
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 Joins pancreatic duct at hepatopancreatic at hepatopancreatic ampullaampulla
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 worn-out and dying red and Kupffer cells phagocytize worn-out and dying red and
white blood cells, some bacteriawhite blood cells, some bacteria
SynthesisSynthesis Albumins, fibrinogen, globulins, heparin, clotting factorsAlbumins, fibrinogen, globulins, heparin, clotting factors
Blood and Bile FlowBlood and Bile Flow
Duct SystemDuct System
GallbladderGallbladder
Bile is stored and concentratedBile is stored and concentrated Stimulated by cholecystokinin and Stimulated by cholecystokinin and
vegal stimulationvegal stimulation 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
PancreasPancreas
AnatomyAnatomy EndocrineEndocrine
Pancreatic islets Pancreatic islets produce insulin and produce insulin and glucagon glucagon
ExocrineExocrine Acini produce Acini produce
digestive enzymesdigestive enzymes RegionsRegions: Head, : Head,
body, tailbody, tail
SecretionsSecretions Pancreatic juice Pancreatic juice
(exocrine)(exocrine) TrypsinTrypsin ChymotrypsinChymotrypsin CarboxypeptidaseCarboxypeptidase Pancreatic amylasePancreatic amylase Pancreatic lipasesPancreatic lipases Enzymes that Enzymes that
reduce DNA and reduce DNA and ribonucleic acidribonucleic acid
Bicarbonate Ion Bicarbonate Ion ProductionProduction
Gastric hormones:Gastric hormones:
Movement in small Movement in small intestine:intestine:
Mixing: Segmental contraction that occurs in small Mixing: Segmental contraction that occurs in small intestineintestine
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
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 (18-24 hours18-24 hours))
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
Secretions of Large Secretions of Large IntestineIntestine
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
Histology of Large Histology of Large IntestineIntestine
Movement in Large Movement in Large IntestineIntestine
Mass movementsMass movements Common after mealsCommon after meals
Local reflexesLocal reflexes in enteric plexus in 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 Usually accompanied by voluntary movements to
expel feces through abdominal cavity pressure expel feces through abdominal cavity pressure caused by inspirationcaused by inspiration
Reflexes inReflexes in Colon and Colon and Rectum:Rectum:
Digestion, Absorption, Digestion, Absorption, TransportTransport
DigestionDigestion Breakdown of food molecules for Breakdown of food molecules for
absorption into circulation absorption into circulation MechanicalMechanical: Breaks large food particles to : Breaks large food particles to
smallsmall ChemicalChemical: Breaking of covalent bonds by : Breaking of covalent bonds by
digestive enzymes digestive enzymes
AbsorptionAbsorption and and transporttransport Molecules are moved out of digestive tract Molecules are moved out of digestive tract
and into circulation for distribution and into circulation for distribution throughout bodythroughout body
LipoproteinsLipoproteins
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
Water and Ions:Water and Ions:
WaterWater Can move in either Can move in either
direction across wall direction across wall of small intestine of small intestine depending on osmotic depending on osmotic gradientsgradients
IonsIons Sodium, potassium, Sodium, potassium,
calcium, magnesium, calcium, magnesium, phosphate are actively phosphate are actively transportedtransported
Effects of AgingEffects of Aging
Decrease in mucus layer, connective Decrease in mucus layer, connective tissue, muscles and secretionstissue, muscles and secretions
Increased susceptibility to infections Increased susceptibility to infections and toxic agentsand toxic agents Ulcerations and cancersUlcerations and cancers
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