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Chapter 28: Small Intestine

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Where is the largest number of hormone-producing cells found in the body?

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A. The pituitary

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B. The small intestine

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C. The pancreas

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D. The liver

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Answer: B

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The small intestine is the body’s largest reservoir of hormone-producing cells. Multiple specialized cells within the intestinal mucosa respond to luminal stimuli and secrete over 30 peptide hormones which regulate the functions of the intestine, other organs in the gastro-entero-pancreato-biliary system, the heart, and the brain (See Schwartz 10th ed., p. 1145.)

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Which of the following features is characteristic of the ileum, as opposed to the jejunum?

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A. The presence of valvulae conniventes

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B. The presence of Peyer patches

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C. Larger vasa recta

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D. Less fatty mesentery

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Answer: B

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The entire small intestine contains valvulae conniventes, also known as plicae circularis. The jejunum has larger vasa recta, a larger diameter, and a less fatty mesentery. The ileum contains prominent lymphoid follicles called Peyer patches. (See Schwartz 10th ed., p. 1138.)

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Within the intestine, epithelial cells originate from stem cells, proliferate in the crypts, and migrate up the villus in 2 to 5 days. This process replaces cells that are removed due to apoptosis or exfoliation. This rapid turnover makes the small intestine susceptible to

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A. Radiation damage

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B. Starvation

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C. Exogenous steroids

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D. Hypothermia

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Answer: A

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The high cellular turnover rate of enterocytes makes the small intestine susceptible to damage by inhibitors of proliferation such as radiation and cytotoxic chemotherapy. (See Schwartz 10th ed., p. 1138.)

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A pocket- or sock-like outpouching on the anti-mesenteric side of the distal ileum, called a Meckel diverticulum, is caused by

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A. Excessive traction on the intestine during childbirth.

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B. Increased intraluminal pressure.

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C. A persistent vitelline duct.

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D. A mutation of the c-Mec gene.

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Answer: C

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The embryonic gut communicates with the yolk sac by mean of the vitelline duct. Failure of this structure to obliterate by the end of gestation can ...

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