This source offers an overview of the digestive system, starting from the mouth and tracing the path of food through the stomach, where initial protein breakdown occurs and the acidic environment eliminates pathogens. It highlights the lack of absorption in the stomach and how the speed of gastric emptying is influenced by food composition (carbohydrates being fastest, fats slowest). The majority of digestion and absorption, it explains, takes place in the small intestine, emphasizing its extensive surface area created by villi and microvilli, the role of brush border enzymes in final digestion, and the unique absorption pathways for fats via the lymphatic system. Finally, the source briefly touches upon the large intestine's function in water absorption and the crucial role of the gut microbiome in digestion and protection against pathogens.