What role does the pancreas play in the enzymatic digestion that occurs in the small intestine? Describe how bile is produced and what role it plays in the breakdown of fats.
When the stomach contents enter the small intestine, the acidity stimulates the pancreas to secrete its digestive enzymes. The pancreas, which is connected to the small intestine by the pancreatic duct, secretes two digestive enzymes, pancreatic amylase and lipase. Pancreatic amylase breaks starches into double sugars. Despite the fact that lipase is the principal fat-digesting enzyme, it is able to hydrolyze only a small percentage of the fats present in food into fatty acids and glycerol. Fat can be absorbed across cell membranes without being completely broken down into fatty acids and glycerol because fat is lipid soluble. Fat is further acted upon by bile which is produced in the liver and stored in the gall bladder, a small organ on the liver's surface. When food enters the small intestine, the gall bladder contracts and forces bile down the bile duct into the small intestine. Bile, which is not an enzyme but a solution containing bile salts, bile pigment, and cholesterol, emulsifies fats into small droplets, increasing the surface area on which lipase can act. Bile also aids in the absorption of fats by the small intestine wall.
