Q. What is the substance produced in the liver that acts in the small intestine during digestion? How does that substance act in the digestive process?

Bile is an emulsifier liquid it is made by the liver and later stored within the gallbladder and released in the duodenum.

Bile is composed of bile salts, bile pigments and cholesterol. Bile salts are detergents, amphiphilic molecules that are molecules with a polar water-soluble portion and a non-polar fat- soluble portion. This feature allows bile salts to enclose fats inside water-soluble micelles in a process called as emulsification for them to be in contact with intestinal lipases, enzymes that break fats into simpler glycerol and fatty acids.