Villi and microvilli

Human nutrition · Absorption · note 2 of 2

Spec 7.5.3, 7.5.4, 7.5.5

Supplement

Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean

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Villi and microvilliSpec 7.5.3, 7.5.4, 7.5.5

In short

Villi are tiny finger-like projections lining the small intestine, and the cells on their surface have even smaller projections called microvilli. Together they greatly increase the internal surface area for absorption. Each villus has a wall one cell thick, a network of capillaries that absorb glucose and amino acids, and a lacteal that absorbs fatty acids and glycerol.

The inside of the small intestine is covered in tiny finger-like projections called villi (singular: villus). The cells on the surface of each villus have even smaller projections called microvilli.

Villi and microvilli greatly increase the internal surface area of the small intestine. A larger surface area means more nutrients can be absorbed into the blood in a given time.

Structure of a villus

The wall is a single layer of epithelial cells, so the distance for nutrients to travel is short.
The epithelial cells have microvilli, which increase the surface area further.
Inside the villus there is a network of capillaries and a lacteal.

Section through a villus showing the epithelium one cell thick with microvilli on its surface, a network of blood capillaries and a central lacteal; glucose and amino acids move into the blood capillaries and fatty acids and glycerol move into the lacteal. — A villus: microvilli and a thin epithelium give fast absorption; **glucose and amino acids** enter the capillaries, **fatty acids and glycerol** enter the lacteal.

Roles of capillaries and lacteals

Capillaries and lacteals
Structure	Role
Capillaries	Absorb glucose and amino acids (and other nutrients) into the blood; the flowing blood carries them away, which keeps absorption going
Lacteal	A lymph vessel in the centre of the villus that absorbs fatty acids and glycerol and carries them away in the lymph

Exam tip:

For a 'how is a villus adapted' question: large surface area (villi and microvilli), thin wall (one cell thick) and a good blood supply (capillaries). Always link the feature to absorption.

Quick check

Where are nutrients absorbed?
Show answer
The small intestine.
Where is most water absorbed?
Show answer
The small intestine (some is absorbed in the colon).
Supplement What is the role of villi and microvilli?
Show answer
They increase the internal surface area of the small intestine.
Supplement What does the lacteal absorb?
Show answer
Fatty acids and glycerol.

Written and checked against the Cambridge IGCSE Biology (0610) specification · Updated October 2026

Frequently asked questions

How is the small intestine adapted for absorption?

Supplement The small intestine is lined with villi, and the cells on each villus have microvilli, which greatly increase the surface area for absorption. Each villus has a wall only one cell thick, so the distance is short, and a network of capillaries gives a good blood supply that carries nutrients away and keeps absorption going.

Where is water absorbed in the digestive system?

Most water is absorbed from the small intestine, and some is also absorbed from the colon. The small intestine also absorbs nutrients such as glucose, amino acids, fatty acids and glycerol, vitamins and mineral ions. In an exam, say 'mostly in the small intestine and some in the colon', not 'colon only'.

What is the function of the lacteal in a villus?

Supplement The lacteal is a lymph vessel in the centre of each villus. It absorbs fatty acids and glycerol and carries them away in the lymph. The capillaries in the villus absorb glucose and amino acids into the blood instead, and the flowing blood carries them away so absorption keeps going.

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