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Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Key diagram
A villus is a finger-like projection lining the ileum. It has a thin epithelium (one cell thick), a dense network of blood capillaries, a lacteal for absorbing fats, microvilli for increased surface area, and a good blood supply to maintain concentration gradients.
The villus diagram combines structure and function in a way examiners love. Every adaptation must be linked to how it increases the rate or efficiency of absorption of digested food molecules.
Drawing the villus
Draw an elongated finger-like projection. The outer surface is a single layer of epithelial cells: draw these as thin rectangular cells. On the surface of each epithelial cell, draw tiny projections called microvilli. Inside the villus, draw a network of blood capillaries close to the epithelial surface and a central tube called the lacteal (part of the lymphatic system).
Adaptations for absorption
(1) Large surface area: millions of villi and microvilli vastly increase the surface area of the ileum wall. (2) Thin epithelium: the wall is one cell thick, giving a short diffusion distance. (3) Rich blood supply: the dense capillary network carries absorbed molecules away quickly, maintaining a steep concentration gradient. (4) Lacteal: absorbs the products of fat digestion (fatty acids and glycerol) into the lymphatic system.
What is absorbed and how
Glucose and amino acids are absorbed into the blood capillaries, mostly by active transport (with some diffusion). They travel in the blood to the liver via the hepatic portal vein. Fatty acids and glycerol are absorbed into the lacteal and enter the lymphatic system before eventually joining the blood. Absorption of water also occurs throughout the small intestine.
Label checklist
Check these labels are present and correctly positioned before finishing your drawing.
✓Villus (finger-like projection)
✓Epithelial cells (one cell thick)
✓Microvilli
✓Blood capillary network
✓Lacteal
✓Goblet cell (mucus-secreting)
Try a diagram question (4 marks)
Explain how the structure of a villus is adapted for the efficient absorption of digested food. [4]
Show the answer and marking guidance
Villi and microvilli provide a large surface area for absorption.
The epithelium is one cell thick, giving a short diffusion distance.
A rich network of blood capillaries maintains a steep concentration gradient by carrying absorbed substances away.
The lacteal absorbs fatty acids and glycerol from fat digestion.
Original Cambridge-style practice written for this site.
Common diagram mistakes
Check these against your own drawing before moving on.
Drawing the villus wall as thick: it must be one cell thick.
Forgetting the lacteal inside the villus.
Stating that fats are absorbed into the blood capillaries: they enter the lacteal.
Not mentioning microvilli, which further increase surface area.
Writing "large surface area" without explaining how (villi and microvilli).