Digestive System Anatomy Digestive System Anatomy Digestive tract Digestive tract Alimentary tract or Alimentary tract or canal canal GI tract GI tract Accessory Accessory organs organs Primarily glands Primarily glands Regions Regions Mouth or oral Mouth or oral cavity cavity Pharynx Pharynx Esophagus Esophagus Stomach Stomach Small intestine Small intestine Large intestine Large intestine Anus Anus
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Digestive System Anatomy Digestive tract Alimentary tract or canal GI tract Accessory organs Primarily glands Regions Mouth or oral cavity Pharynx Esophagus.
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Digestive System Digestive System AnatomyAnatomy
Digestive tractDigestive tract Alimentary tract or Alimentary tract or
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
FunctionsFunctions
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
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
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:
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))
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:
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