Nutrition in Humans

What you'll learn

How the digestive system breaks food down and absorbs it, what each organ does, how villi are built for absorption, and how the liver processes absorbed nutrients.

• Four separate stages: ingestion, digestion, absorption, assimilation, egestion
• Peristalsis pushes food along the gut
• The mouth and salivary glands start digestion mechanically and chemically
• The stomach churns food and starts protein digestion
• The duodenum receives secretions from the pancreas, liver and gall bladder
• Digestive enzymes each break down one type of substrate
• Bile is not an enzyme, it physically breaks fat into droplets
• The ileum's villi are built for absorbing digested food
• The hepatic portal vein sends absorbed nutrients straight to the liver
• The liver processes nutrients and breaks down harmful substances
• The colon, rectum and anus complete the process