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GERD

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alchemist04's version from 2018-06-15 05:17

Section

TermDefinition/function
4 Secretion cells of the stomach1) Mucous 2) Parietal 3) Chief 4) Endocrine (G cells)
Location and function of Mucous cellsCardia and Antrum, Secrete Mucous
Location and function of Parietal CellsFundus and Body, Gastric Acid secretion
Location and function of Chief cellsFundus and Body, Secretion of Lipase and Pepsinogen
Location and function of Endocrine (G cell)Antrum, Gastrin Secretion
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TermDefinition/function
What are the 3 ways Parietal cells are stimulated to secrete H+Thru 1) ACh 2) Histamine 3) Gastrin
How does Parietal Cells secrete HCl?The venous blood vessel carries CO2 which diffuses thru the Parietal Cells. In the Parietal Cells, the CO2 combines with H20 to form carbonic acid and with the help of Carbonic anhydrase (H2CO3), dissociation takes place and H+ with bicarbonate (HCO3-) are formed. The H+ passes into the lumen of the stomach via H+/K+ ATPase pump. As H+ moves into the lumen, the K+ moves into the Parietal Cell. The bicarbonate ion is diffused back into the venous blood vessel causing alkaline tide and in exchange for Cl-. The Cl- is then diffused into the lumen where it combines with H+ and form HCl.
Why do we need to know the formation of HCl in the Parietal cells Cells?Because H+ causes acidic state in the stomach and it passes into the lumen via H+/K+ ATPase Pump which is also known as Proton Pump. Hence, Proton Pump Inhibitors (the Prazoles) for acid reflux or GERD
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TermDefinition/function
What are the 2 ways the stomach is prevented from gastric acid?1) Tight junctions prevent leakage 2) Bicarbonate rich mucus lining the stomach and maintain pH of 6-7
How does G cell affect HCl secretion?G cell produces Gastrin which stimulates the release of Histamine in the ECL cells. This induce the insertion of H+/K+ ATPase pumps into the apical membrane of parietal cells. Hence, increase the amount of H+ crossing into the stomach.
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TermDefinition/function
How does ACh (Acetylcholine) effect gastric secretion?ACh is released by stimulation of Val and Intramucosal reflex, which act directly on parietal cell. The stimulation of these parasympathetic nervous system causes Muscranic receptors to bind to ACh. The binding of ACh and Muscarinic receptors causes an increase in intracellular Ca2++. The Ca2++ causes increase in Protein Kinases. The increase in Protein Kinases cause increase in H+/K+ ATPase
What is the PGE2 role in Gastric Secretion and mechanism?PGE2 acts in opposition to Histamine by decreasing intracellular cAMP
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TermDefinition/function
Receptive relaxationIt is when stomach relaxes to allow food to enter as food moves down esophagus. Gastric fundus dilates as food move thru the esophagus.
What increases the magnitude and frequency of stomach contractions while mixing food?Gastrin and ACh
How does food move from stomach to small intestine?Gastrin and ACh influence contraction of the muscles while pyloric sphincter filters food, 3 meals at a time
What moves more readily?Carb moves more readily than fats
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TermDefinition/function
What is LES?Lower Esophageal Sphincter
What is the relationship btw GERD and LES?In normal digestion, the LES opens to allow food to pass into the stomach and closes to prevent food and acidic stomach juices from flowing back into the esophagus. GERD occurs when the LES is weak or relaxes inappropriately, allowing the stomach's content to flow up into the esophagus
What are the conditions that can decrease LES sphincter tone and cause abnormal pressure?1) Alcohol/Tobacco 2) Delayed gastric emptying 3) Increased gastric volume
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