Where is the largest number of hormone-producing cells found in the body?
The small intestine is the body's largest reservoir of hormoneproducing 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.
Which of the following features is characteristic of the ileum, as opposed to the jejunum?
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.
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:
The high cellular turnover rate of enterocytes makes the small intestine susceptible to damage by inhibitors of proliferation such as radiation and cytotoxic chemotherapy.
A pocket- or sock -like outpouching on the anti-mesenteric side of the distal ileum, called a Meckel diverticulum, is caused by:
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 result in a Meckel diverticulum.
How much fluid normally enters the adult small intestine each day?
Eight to nine liters of fluid enters the small intestine daily, of which over 80% is absorbed. This includes 2 L from oral intake, 1.5 L of saliva, 2.5 L of gastric juice, 1.5 L of biliopancreatic secretions, and 1 L of fluid secreted by the small intestine.
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