Topic overview

Start with the big picture

Digestion begins with enzymes such as salivary amylase and continues through pancreatic and brush-border activity. The resulting nutrients cross the intestinal lining through distinct transport pathways: for example, SGLT1 carries glucose and galactose, while GLUT5 carries fructose. Protein fragments and fats follow different routes, with long-chain fatty acids packaged for lymphatic transport and shorter-chain fatty acids entering portal blood. The topic also maps where selected micronutrients are absorbed, including vitamin B12 in the terminal ileum and iron in the duodenum, and explains the roles of bile-acid recycling, water movement, and gastrointestinal hormones such as secretin and CCK. These pathways provide a framework for understanding digestion and absorption alongside related clinical disorders.