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27 Cards in this Set
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What are the contents of the gastric juice in the stomach?
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Cations: H+, Na+, K+, Mg+
Anions: Cl-, HPO4, SO4 volume: 2-3 L/day Organic substances: -Enzymes -Mucin -Intrinsic Factor |
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What are the enzymes in the Gastric Juice?
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Pepsinogen:
-inactive form of pepsin (zymogens) -converted to active enzymes by: HCl and autocatalytically -inactivated in duodenum -digestion of pepsin is incomplete in stomach and finishes in small intestine Gastric Lipase: -optimum pH between 4.5 and 5.5 but stable at pH of 2.0 -more active against triglycerides containing short FA (tributyrin of butter fat) -contribute to fat digestion more when pancreatic function decreases Gelatinase: -liquefies gelatin (faster than pepsin) Rennin: -milk clotting factor |
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What is the function of HCl and what is the mechanism of its secretion?
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Functions:
-non specific defense mechanism -pepsinogen activation -optimal low pH for pepsin actions -denatures proteins, breaks down CT and muscle fibers -absorption of Ca2+ and iron Secretion: Source of H+ ions: -NOT from carbonic acid, rather produced by dissociation of water or respiratory chain enzymes -OH- is neutralized by CO2 combined with carbonic anhydrase -H+ pumped out by proton pump (H+/K+ exchanger) -HCO3 produced by carbonic anhydrase moves out on blood side in exchange for Cl- -Cl- goes by facilitated diffusion into the canaliculi -transport of Cl- and H+ are closely linked but secreted separately -H2O osmosis out of cell |
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How is Gastric secretion controlled?
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Ach - stimulates secretion by all secretion cell types, reaches mast cells by diffusion (NO PSNS)
Histamine and gastrin - mainly stimulate parietal cell secretion PSNS stimulates direct secretion of gastrin by GRP (neurotransmitter) and indirectly by decrease somatostatin release by D cells |
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What is the Gastric Mucosa Barrier?
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mixture of HCl and pepsins is corrosive
First line of defense -water insoluble gel of mucus and bicarbonate: -decrease flow of H+ but permeable to Pepsin (mucus can be degraded by pepsins) -bicarbonate provides buffer, making enzymes less active -mucus + fibrin = possibility of tissue repair Mucosal phospholipids (hydrophobic): -decrease permeability of epithelium to H+ Natural foods containing phospholipids or similar (banana) provide additional protection |
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What are the different types of Gastric and Peptic Ulcers?
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Peptic Ulcers:
-HCl erodes mucus membrane of stomach or duodenum Zollinger-Ellison syndrome: -ulcer of duodenum by excessive gastric acid secretions Helicobacter pylori: -bacterium in GI tract that may produce ulcers Acute gastritis: -histamine released by tissue damage, inflammation causes further acid secretion |
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What is the digestive phase of Gastric motility and how is the stomach emptied?
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Receptive relaxation of proximal stomach:
-opening of UES and food enters into stomach --> relaxation of stomach --> increase in gastric volume WITHOUT increase in P --> storage with little mixing Accommodation reflex: -vago vasal reflexes by swallowing center Tonic contraction of proximal stomach: -increase intragastric pressure -proximo-distal pressure gradient -content goes to distal stomach Peristalsis: -propulsion toward antrum -pyloric sphincter contracts and gastric content is pressed toward pylorus and compressed -increase in pressure of the antrum --> small portion of content moves into duodenum Retropulsion: -contraction of pyloric sphincter -antrum churns trapped material and moves back into body of stomach Emptying: -increase basal tone of proximal stomach -propulsive peristalsis -systolic contraction --> pumping actions force pyloric sphincter to open -receptive relaxation of duodenal bulb Consequences: -too rapid gastric emptying --> duodenal ulcer -too slow --> exacerbation of gastric ulcers -regurgitation of duodenal content (bile) into stomach --> gastric ulceration |
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What happens in Vomiting?
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Act:
-deep inspiration -closing of glottis -contraction of abdominal muscles -contraction of pylorus and antrum -relaxtion of LES and UES -antiperistalsis Importance: -removal of ingested toxic substances -protective conditioning Danger of excessive: -loss of large amounts of water & electrolytes --> dehydration, metabolic alkalosis |
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What are parts of the Pancreas structure?
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Exocrine acini:
-secrete pancreatic juice Endocrine Islet of Langerhans: -secrete hormones |
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What is the max package size the USPS will accept for shipment (length & girth)?
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- weight limit of 70 lbs
- size limit of 108" - size limit of 130" depenging on whether it is sent by priority or package service |
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What are the main enzymes in pancreatic juice?
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Trypsin:
-Zymogen = Trypsin -Activator = Enterokinase -cleaves internal peptide bonds Chymotrypsin: -Zymogen = Chymotrypsinogen -Activator = Trypsin -cleaves internal peptide bonds Elastase: -Zymogen = Protease -Activator = Trypsin -Cleaves internal peptide bonds Carboxypeptidase: -Zymogen = Procarboxypeptidase -Activator = Trypsin -cleaves C Terminal AA Phospholipase: -Zymogen = Prophospholipase -Activator = Trypsin -cleaves FA such as Lecithin Pancreatic Trypsin inhibitor attaches to trypsin and inhibits activity in the pancreas - prevents pancreatic autodigestion |
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How is Pancreas Secretion Regulated?
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Stimulation of acinar cells - secretion of enzymes
-Ach -Gastrin -CCK-PZ (upper small intestine) Stimulation of ductal cells - secertion of Sodium Bicarbonate and water: -Secretin -HCl in duodenum --> entero-pancreatic vago-vagal reflex --> bicarbonate secretion |
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What are Lobules?
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Functional units of the liver
Components: -Hepatocytes -Capillary sinusoids -Kuppfer Cells -Bile Canaliculi |
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What is the path of the Hepatic Artery and Hepatic Portal Vein?
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Oxygenated blood from artery and nutrient rich deoxygenated blood from vein --> liver sinusoids --> central vein --> hepatic vein --> IVC --> right atrium of heart
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What is the flow of Bile from the Liver?
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Right Hepatic duct and Left Hepatic duct --> Common Hepatic duct from liver --> common bile duct (along with cystic duct from galbladder) --> duodenum (along with pancreatic duct from pancreas)
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What are the functions of the Liver?
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Detoxification of blood:
-phagocytosis by Kupffer cells -production of urea, uric acid -excretion of molecules in bile Carbohydrate Metabolism: -conversion of blood glucose to glycogen and fat -secretion of glucose in blood Lipid Metabolism: -synthesis of triglycerides and cholesterol -excretion of cholesterol in bile -production of ketone bodies from FA Protein Synthesis: -production of albumin -production of plasma transport proteins -production of clotting factors Secretion of Bile: -synthesis of bile salts -excretion of bile pigment (bilirubin) Storage: -Vit A, E, K, B12 |
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What is Bile composed of?
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Bile is secreted CONTINUALLY but delivered INTERMITTENLY into duodenum when sphincter of Oddi is opened
when sphincter cloes bile flows to galbladder Galbladder: Function: -storage of bile (decreases volume due to concentration of bile) -concentration of bile - active transport of Na+ --> passive transport of Cl, HCO3, and water -ejection of bile by contraction of smooth muscle (following meal) Bile: -components - water, electrolytes (bicarbonate --> pH 7.6 - 8.6, lecithin, cholesterol, bile acids and salts |
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What are characteristics of Bile Acids/Salts and functions?
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Bile acids are derived from cholesterol
Principal Bile Acids: -Cholic acid -Chenodeoxycholic acid Production of bile salts: cholesterol --> bile acids --> conjugation of taurine and glycine --> formation of Na+ and K+ salts in alkaline hepatic bile Advantages of Conjugation: -increase solubility of small intestine -decrease passive reabsorption in Upper small intestine Recycling of Bile Salts: -95 % conjugated bile acids absorbed in terminal ileum of small intestine --> enterhepatic circulation --> resecretion into bile Functions: -Emulsification of Fats - decrease size of fat droplets --> increase SA available for pancreatic lipase action -Hydrotropic effects - increase micelle formation in small intestine which keep fat digestion in water soluble form; increase lipid transport -Activation of Pancreatic Lipase - alteration of pH optimum from 8.9 - 6.7 Choleretic action - stimulation of bile flow Increase water and electrolyte secretion in colon - osmotic diarrhea |
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How is Bile Secretion regulated?
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Choleretics - increase bile secretion
-secretin -bile acids -PSNS (increase in secretion), SNS - decrease (vasoconstriction) Cholagogues - cause contraction of galbladder (CCK is most potent stimulator of galbladder) Relaxation of sphincter of Oddi |
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What is Jaundice?
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excessive bilirubin in plasma and body fluids
3x normal for color Pre-hepatic - before liver excessive bilirubin production Hepatic - in liver, damage to liver cells Post-hepatic - blockage to bile flow from liver |
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What are Gallstones?
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2 types:
-cholesterol stones -calcium bicarbonate stones How stones are formed: -increase absorption of water in galbladder -increase absorption of bile acids (decrease solubility of cholesterol) -increase cholesterol concentration (fatty diet) -inflammation of epithelium |
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What are the parts of the Small Intestine?
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Duodenum
Jejunum Ileum - joins large intestine at ileocecal sphincter Walls: -Circular folds - plicae circularis of mucosa and submucosa; function to increase SA and enhance reabsorption, increase chyme mixing -Villi - fingerlike projections of the mucosa; increase SA Microvilli - contain actin filaments and make up the brush border; increase SA of plasma membrane and contain digestive enzymes |
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What is in the Intestinal Wall of the Small Intestine?
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Absorptive cells - absorb nutrients
Goblet cells - secrete mucus Enterendocrine cells - secrete secretin, cholecystokinin, or GIP Paneth cells - secrete lysozyme and is capable of phagocytosis duodenum contains Brunner's gland (located in submucosa) that secretes alkaline mucus Crypts of Liberkuhn - glandular epithelium lining deep intestinal crevices MALT - peyer's patches in the ileum |
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What are the parts of the Large Intestine?
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cecum, colon, rectum, anal canal
extends from ileocecal valve to anus cecum: -contains an ileocecal flap that is a fold of mucous membrane that allows content of small intestine to pass into large intestine Ileocecal valve: Sphincter: -tonically constricted -relaxes when chyme leaves stomach and when ileum fills and contracts -contracts when cecum is filled Valve: -prevents reflux of cecal content into ileum Anal Canal: -has anal columns which are folds of mucous membrane, contain blood vessels Internal Anal Sphincter: -circular smooth muscle -SNS innervation = inferior hypogastric nerves causing tonic contraction -PSNS innervation = pelvic nerves --> relaxation External Anal Sphincter: -striated muscle fibers -Innervation = somatic pudendal nerve Rectum: factors that maintain empty state of rectum: -sharp angle between sigmoid colon and rectum -weak function sphincter between these segments -periodic character of mass peristalsis of colon |
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What are characteristics of the Histology of the Large Intestine?
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4 layers: mucosa, submucosa, muscularis, serosa
Tunica muscularis: -muscle forms 3 bands = teniae coli -runs entire length of colon, sacculations of the colon |
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What is the Mechanism of Defecation?
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Intrinsic (local) reflex:
-movement of feces --> distension of rectal wall -activation of stretch receptors -myenteric plexus -peristalsis waves -feces moves towards anus -relaxation of internal sphincter Spinal Parasympathetic Reflex: -Stimulus = distension of rectum -Receptors = rectal stretch receptors -Afferents = parasympathetic fibers -Integrative center = sacral segments of spinal cord -Efferent = pelvic nerves -Effectors = descending colon, sigmoid, and rectum --> peristalsis, distends from rectum and increases intrarectal pressure; involuntary relaxation of internal sphincter |
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What are the Somatic and Voluntary Components of Defecation?
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Voluntary inhibition of urge and postponement:
-contraction of external sphincter -relaxation of rectum -contraction of levator ani mm Conscious decision to defecate: -relaxation of external sphincter -contraction of rectal longitudinal mm -proximo-distal pressure gradient causes defecation Factors that facilitate defecation: -contraction of abdominal mm, deep inspiration --> increase intraabdominal pressure -relaxation of pelvic floor, flexure of hip minimizes angle between rectum and anus |
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