High School

Which of the following are caused by the release of cholecystokinin by duodenal enteroendocrine cells in response to protein- and fat-rich chyme? Select all that apply.

A. Increased production of HCO₃⁻ by pancreatic duct cells
B. Increased secretion of pancreatic juice by acinar cells
C. Increased bile secretion by the liver
D. Suppression of gastric emptying
E. Relaxation of the hepatopancreatic sphincter
F. Gall bladder contraction

Answer :

Cholecystokinin (CCK) causes 2) increased secretion of pancreatic juice, 4) suppression of gastric emptying, 5) relaxation of the hepatopancreatic sphincter, and 6) gallbladder contraction. CCK's role is distinct from secretin, which stimulates bicarbonate secretion by pancreatic duct cells.

Cholecystokinin (CCK) is a hormone released by duodenal enteroendocrine cells in response to protein- and fat-rich chyme. The effects of CCK include:

  • 2) Increased secretion of pancreatic juice by acinar cells due to the enzymatic component.
  • 4) Suppression of gastric emptying to allow time for digestive enzymes and bile to act.
  • 5) Relaxation of the hepatopancreatic sphincter, allowing pancreatic juice and bile to flow into the duodenum.
  • 6) Gallbladder contraction, pushing bile into the intestine for fat digestion.

Though CCK stimulates secretion of enzyme-rich pancreatic juice, it is secretin that stimulates pancreatic duct cells to produce bicarbonate (HCO₃). Increased bile secretion is due to the liver receiving signals to increase production and release of bile, which is then stored in the gallbladder until CCK stimulates its contraction. It's important to differentiate between the roles of CCK and secretin in the digestive process.

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