Advanced Dental Admission Test (ADAT)

What is the primary function of I Cells in the small intestine?

1. To produce HCl

2. To secrete pepsinogen

3. To produce cholecystokinin (CCK)

4. To increase surface area

The correct answer is: To produce cholecystokinin (CCK)

The primary function of I Cells in the small intestine is to produce cholecystokinin (CCK). These cells are located in the duodenum, which is the first part of the small intestine. CCK plays a crucial role in the digestive process by stimulating the gallbladder to contract and release bile, which is essential for the emulsification and digestion of fats. Additionally, CCK signals the pancreas to secrete digestive enzymes, aiding in the digestion of proteins and carbohydrates. This function is vital for proper digestion and nutrient absorption, especially after the consumption of a meal high in fats. By producing CCK, I Cells help coordinate the digestive process, ensuring that the necessary enzymes and bile are released at the right time. In contrast, other options refer to functions that are not associated with I Cells. For instance, the production of hydrochloric acid (HCl) is primarily attributed to parietal cells in the stomach, while the secretion of pepsinogen is related to chief cells, also in the stomach. The role of increasing surface area pertains to the structure of the intestine itself, such as villi and microvilli, rather than a specific cell type.