Question

Match each statement to an answer in the key. Answers may be used more than once. Some may have more than one answer. a. gastrin b. secretin c. \(\mathrm{CCK}\) d. All of these are correct. e. None of these is correct. Stimulates gallbladder to release bile

Short answer

The correct answer is c) CCK (Cholecystokinin) as it promotes gallbladder contraction, stimulating the release of bile.

Step-by-step solution

Find the hormone responsible for gallbladder bile release

Upon analyzing the function of each hormone: a) Gastrin primarily stimulates acid secretion in the stomach b) Secretin stimulates the pancreas to release digestive enzymes and bicarbonate, and the liver to secrete bile c) CCK (Cholecystokinin) promotes gallbladder contraction, thus stimulating the release of bile

Select the correct answer

According to the functions of these hormones, CCK (Cholecystokinin - c.) is the hormone that stimulates the gallbladder to release bile. The correct answer is c) CCK.

Key concepts

Gastrin

Gastrin is a hormone that plays a critical role in the digestive system. It's produced by 'G' cells in the lining of the stomach and duodenum when food, especially protein, enters the stomach.

Once released into the bloodstream, gastrin has several important functions. Primarily, it stimulates the parietal cells of the stomach to secrete hydrochloric acid (HCl), which is crucial for the digestion of food as it denatures proteins and activates pepsinogen into pepsin.

Gastrin also has a role in gastric motility, encouraging the stomach muscles to contract, which helps in churning food to mix it with gastric juices for digestion. While gastrin does influence the digestive tract, it does not directly act on the gallbladder to release bile, thus, for the specific exercise regarding bile release, gastrin is not the correct answer.

Secretin

Secretin, produced by the 'S' cells of the duodenum, is another hormone with a specific role in digestion but not in the direct stimulation of bile release from the gallbladder. When acidic food from the stomach enters the small intestine, secretin is released into the bloodstream.

The key functions of secretin include:

• Stimulating the pancreas to secrete pancreatic juice that is rich in bicarbonate ions. This helps neutralize the acid coming into the small intestine from the stomach.
• Encouraging the liver to produce bile more rich in water and bicarbonate, making it more effective in neutralizing stomach acid, but not in increasing bile release from the gallbladder.

Despite its significant contributions to the digestive process, secretin's role is more to prepare for the arrival of chyme (the mix of digested food and stomach acid) into the intestines and not the contraction of the gallbladder.

Cholecystokinin

Cholecystokinin, commonly abbreviated as CCK, is the primary hormone responsible for stimulating the gallbladder to contract and release stored bile. Produced by the 'I' cells of the duodenum and jejunum primarily in response to fats and amino acids in food, CCK has several key functions which include:

• Stimulating the gallbladder to contract, which pushes bile into the cystic duct, and then into the common bile duct, leading to the small intestine.
• Inducing the pancreas to secrete digestive enzymes that help in the digestion of fats and proteins.
• Slowing down the rate of gastric emptying to allow more time for digestion of fats and proteins.

In the exercise, the match for the hormone that stimulates the gallbladder to release bile is CCK. This is because CCK directly targets the gallbladder, causing it to contract and dispense its bile into the small intestine, where it emulsifies fat, making it easier for lipases to break the fats down into fatty acids and glycerol for absorption by the body.