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Chapter 19: Small Bowel

Which of the following is true of cholecystokinin (CCK)?

(A) Its release stimulates pancreatic acinar cell secretion, pancreatic growth, and insulin release.

(B) It is a peptide hormone.

(C) Its release stimulates gallbladder contraction and sphincter of Oddi relaxation.

(D) It is released by the small bowel in response to contact with amino acids.

(E) All of the above.

(E) Cholecystokinin is a peptide hormone predominantly produced by I cells in the duodenum and jejunum in response to the ingestion of fats, peptides, and amino acids. Trypsin and bile acids inhibit its release. The overall function of CCK is to improve digestion and absorption of key nutrients.

Cholecystokinin stimulates contraction of the gallbladder and relaxation of the sphincter of Oddi, making it useful in assessing for biliary dyskinesia with CCK hepatic iminodiacetic acid (HIDA) scans. It also stimulates secretion of enzymes by pancreatic acinar cells and slows gastric emptying by affecting muscular contraction of the pylorus. CCK has a trophic effect on small bowel mucosa and on pancreas cells, and it may also play a role in intestinal motility and insulin release. Finally, CCK acts to produce a sense of satiety.



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A 45-year-old woman presents to the emergency department with 18 h of nausea, vomiting, and cramping abdominal pain. The pain is not constant, and she denies any associated fevers. She underwent hysterectomy and bilateral oophorectomy 2 years ago. An abdominal series is consistent with a small bowel obstruction. Which of the following is true regarding the natural physiologic barrier that prevents bacterial translocation in this clinical scenario?

(A) The gastrointestinal (GI) tract contains minimal, if any, lymphoid tissue.

(B) The nonimmunologic defenses of the gut include epithelial tight junctions, endogenous bacteria, mucin production, gastric acid, proteolytic enzymes, and peristalsis.

(C) Secretory immunoglobulin (Ig) A prevents colonization of bacteria in the small bowel by stimulating their adherence to the ...

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