Final answer:
The hormone that controls the release of bile from the gallbladder is cholecystokinin (CCK). CCK is released when fat enters the small intestine, triggering the gallbladder to contract and secrete bile, which is crucial for the digestion and absorption of fats.
Step-by-step explanation:
Control of Bile Release by Hormones
The process of digestion involves the breakdown of food into its constituent nutrients, which can be absorbed by the body. An important aspect of this process is the emulsification and digestion of fats, which is aided by bile. Bile is a digestive fluid produced by the liver, stored in the gallbladder, and released into the small intestine. The release of bile is critical for the digestion of fats and is controlled by hormonal signals.
The Role of Cholecystokinin (CCK)
When fat is present in the chyme (the partially digested food that moves from the stomach to the small intestine), the hormone responsible for signalling the release of bile from the gallbladder is cholecystokinin (CCK). CCK is produced by cells in the intestinal mucosa in response to the presence of fatty acids in the small intestine. Once released, CCK stimulates the gallbladder to contract and release stored bile into the duodenum through a series of ducts. Additionally, CCK prompts the secretion of pancreatic lipase from the pancreas, which is an enzyme crucial for the further breakdown of fats.
The action of CCK is essential for lipid metabolism, as it ensures that bile is secreted to meet with the fats as they enter the small intestine, facilitating their digestion. This process not only aids in digestion but also in the absorption of fat-soluble vitamins and the elimination of excess cholesterol from the body.
The hormone secretin also plays a role in bile production by stimulating hepatocytes in the liver during the presence of fatty chyme in the duodenum. However, it is primarily CCK that triggers the gallbladder to release bile. Understanding the role of these hormones in the digestion process is important for comprehending how the body manages and utilizes nutrients.