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28 Cards in this Set
- Front
- Back
- 3rd side (hint)
actions of gastrin?
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(G cells of antrum) inc'd gastric H+; stim growth of gastric mucosa
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what stimulates release of gastrin?
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sm peptides, amino acids in stomach lumen; stomach distention; vagus (via GRP)
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where is CCK from?
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I cells of duodenum
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5 actions of CCK
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1. stim gallbladder contraction and Oddi relaxation; 2) stim pancreatic enzyme secretion; 3) potentiates secretin-induced stim of pancreatic bicarb secretion; 4) stim growth of exocrine pancrease; 5) inhibits gastric empyting
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what stimulates release of CCK from duodenum?
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small peptides, amino acids; fatty acids and monoglycerides (not TGs b/c can't cross intestinal membrane)
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actions of secretin?
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1. stim pancreatic bicarb (potentiated by CCK) and inc'd growth of exocrine pancrease; 2) stim bicarb and H2O secretion by liver and inc'd bile production; 3) inhibits H+ by gastric parietal cells
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None
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what stimulates release of secretin from S cells of duodenum?
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H+ and fatty acids in duodenum
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actions of GIP (gastric inhibitory peptide)
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1. stimulates insulin release (this is why oral glucose better!) 2. inhibits H+ secretion
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what stimulates release of GIP from K cells?
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fatty acids, amino acids, oral glucose (only GI hormone that responds to fat, protein, and carbs!)
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what inhibits release of somatostatin?
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vagal stimulation
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effect of His on GI
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increased H+ secretion directly and indirectly by potentiating effects of gastrin and vagal stim
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actions of VIP?
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relaxation of GI smooth mm (LES!); stimulate pancreatic bicarb; inhibits H+
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basal electric rhythm of a) stomach b) duodenum c) ileum
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a) 3 Hz; b) 12 Hz; c) 8-9 Hz
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gastroileal reflex?
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food in stomach--> increased peristalsis in ileum and relaxation of ileocecal sphincter
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gastrocolic reflex?
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food in stomach--> increased colon motility and frequency of mass movements
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composition of saliva
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high K+, HCO3-; low NaCl (hypotonic, unless made rapidly); alpha amylase, lingual lipase, kallikrein
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parasympathetic regulation of saliva production?
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CN VII, IX (via muscarinic R IP3 or Ca); inc'd production
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sympathetic regulation of saliva production
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increased production, via beta adrenergic stim (cAMP)
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composition of aq part of pancreatic secretions?
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always ISOTONIC, more bicarb than in plasma; if low flow rate--high Na Cl; if high flow rate--high Na HCO3-
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what does sucrase do?
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degrades sucrose to glucose and fructose
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what does SLGT 1 in intestine do?
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transports glucose and galactose into cells, Na+-dependent
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how is fructose transported into intestinal cells?
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facilitated diffusion
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optimum pH for pepsin activity?
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1-3 (in pH>5, denatures)
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(hypothetical) deficiency of enterokinase--> ?
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no activation of pancreatic proteases b/c it converts tyrpsinogen into trypsin and tryspin then cleaves all the others
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None
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why might hypersecretion of gastrin cause steatorrhea?
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low duodenal pH inactivates pancreatic lipase
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what would a lack of apoprotein B do in intestine?
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cause steatorrhea b/c apo B necessary for transporting chylomicrons out of intestinal cells
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what happens to K+ in GI?
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dietary K+ absorbed paracellularly; activly secreted in colon (similar to in kidney)
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None
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how does Vibrio Cholerae cause diarrhea?
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toxin binds R in luminal membrane, activates AC which causes increase cAMP--> lumenal Cl- channels open. Na and H2O follow Cl--> secretory diarrhea!!
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