What is the role of bile salts produced by the gallbladder?

Bile salts, produced by the liver and stored in the gallbladder, play a critical role in the digestion and absorption of fats. They are amphipathic molecules, meaning they have both hydrophilic (water-attracting) and hydrophobic (water-repelling) properties. When fats enter the small intestine, bile salts emulsify them, breaking them down into smaller droplets. This emulsification increases the surface area for enzymes, such as pancreatic lipase, to effectively act on the fat molecules, leading to their breakdown into fatty acids and glycerol, which can then be easily absorbed by the intestinal lining.

The other options do not accurately describe the primary function of bile salts. Enhancing blood circulation is not a function of bile salts; rather, this is affected by the cardiovascular system. Although bile salts aid in the absorption of fatty acids, they do not directly aid in protein digestion; that process is primarily facilitated by different enzymes. Similarly, while they assist in nutrient absorption, their specific role is more focused on the digestion of fats rather than nutrients in general. Thus, the emphasis on breaking down fats aligns directly with the established understanding of the function of bile salts.