Certified Neuroscience Registered Nurse (CNRN) Practice Exam

What stimulates the secretion of bile from the gallbladder?

1. Cholecystokinin

2. Secretin

3. Gastrin

4. Insulin

The correct answer is: Cholecystokinin

Cholecystokinin is the correct choice as it plays a crucial role in the digestive process, particularly in the response to food intake. When fats and proteins enter the small intestine, the presence of these macronutrients stimulates the cells in the intestinal mucosa to release cholecystokinin. This hormone then promotes the contraction of the gallbladder, leading to the release of bile into the small intestine. Bile is essential for the emulsification and digestion of dietary fats. Therefore, cholecystokinin not only alerts the gallbladder to release bile but also enhances the overall digestive process by stimulating the secretion of pancreatic enzymes, which further aids in the digestion of the fats and proteins present in the food. In contrast, secretin primarily regulates the pH levels in the small intestine by stimulating the pancreas to release bicarbonate, while gastrin stimulates gastric acid secretion in the stomach. Insulin, on the other hand, is a hormone that primarily regulates glucose metabolism and has no direct role in stimulating bile secretion from the gallbladder. Thus, cholecystokinin is specifically responsible for the contraction of the gallbladder and the timely secretion of bile, making it the accurate answer.