This document discusses digestion and absorption of carbohydrates, proteins, and lipids in the gastrointestinal tract. It describes how carbohydrates, proteins, and lipids are broken down by digestive enzymes into smaller molecules that can be absorbed. Carbohydrates are broken into monosaccharides like glucose and fructose. Proteins are broken into amino acids, dipeptides and tripeptides. Lipids are emulsified, formed into micelles, and broken into fatty acids and monoglycerides which are absorbed and resynthesized into triglycerides for transport. The key sites of digestion and enzymes involved are also outlined.