This document summarizes gastrointestinal secretions from several organs. The pancreas secretes enzymes like lipase, amylase and proteases to digest fat, carbohydrates and proteins. The gallbladder stores and concentrates bile produced by the liver which contains bile salts that emulsify fats to aid digestion. The small intestine produces mucus, enzymes to further break down nutrients, and bicarbonate to neutralize acid. The large intestine secretes mucus and bicarbonate to protect its walls. Hormones like CCK and secretin regulate secretions from the pancreas and bile ducts.