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28 Cards in this Set

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