Skip to content
Human Body Study

Small Intestine

A long, coiled tube — around 6 meters — where most digestion is completed and almost all nutrients are absorbed.

The digestive tract The GI tract from mouth through oesophagus, stomach, small intestine and large intestine, with liver, gallbladder and pancreas as accessory organs. Each label links to the article for that part. Mouth Esophagus Liver Stomach Gallbladder Pancreas Small intestine Large intestine The digestive tract and its accessory organs — schematic, not to scale.

Three sections

Section titled “Three sections”
  • Duodenum — receives chyme and mixes in bile and pancreatic enzymes.
  • Jejunum — the main site of nutrient absorption.
  • Ileum — completes absorption.

Structure for absorption

Section titled “Structure for absorption”

The inner surface is folded and covered in finger-like villi and microvilli, multiplying the absorbing surface enormously.

What it does

Section titled “What it does”

Finishes chemical digestion and absorbs sugars, amino acids, fats, vitamins, and minerals into the blood and lymph.

Key idea

Section titled “Key idea”

Despite the name, the small intestine is where digestion’s real payoff happens — its vast inner surface is the body’s main nutrient gateway.