Intestinal villus facts for kids

Structure of a villus

Intestinal villi (say "VILL-eye") are tiny, finger-shaped bumps found inside your small intestine. Think of them like tiny, soft bristles lining the walls of your intestine. Each villus (that's the singular form) is very small, about half a millimeter to one and a half millimeters long in humans. That's about the size of a tiny grain of rice!

Each villus has even tinier structures on its surface called microvilli. These microvilli are super small, about 1,000 times smaller than a single villus. The villi themselves are much smaller than the larger folds you might see inside the intestine.

Why are villi important for digestion?

Villi play a super important role in your body. They help your body get the good stuff from the food you eat!

Increasing surface area

The main job of villi is to make the inside surface of your small intestine much, much bigger. Imagine if your intestine was a smooth tube. It wouldn't have much space to absorb nutrients. But with all these tiny villi and microvilli, the surface becomes huge! It's like crumpling up a large piece of paper into a small ball. The paper still has the same big surface area, even though it takes up less space.

This huge surface area is key for absorbing nutrients. When you eat, your food is broken down into tiny nutrient molecules. These molecules need to move from your intestine into your blood.

How nutrients get absorbed

Nutrients move into the villi through a process called diffusion. Diffusion is how tiny particles spread out from an area where there are many of them to an area where there are fewer. It works best over very short distances.

Because the villi create such a large surface area, the nutrient molecules don't have far to travel to reach the villi. This makes diffusion very efficient. Once the nutrients are inside the villi, they quickly pass into tiny blood vessels. Your blood then carries these important nutrients all over your body, giving you energy and helping you grow.

Images for kids

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  Different stages of coeliac disease

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  Vertical section of a villus from the dog's small intestine. X 80. (Simple columnar epithelium labeled at right, third from top.)

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  Transverse section of a villus, from the human intestine. X 350. a. Basement membrane, here somewhat shrunken away from the epithelium. b. Lacteal. c. Columnar epithelium. d. Its striated border. e. Goblet cells. f. Leucocytes in epithelium. f’. Leucocytes below epbithelium. g. Blood vessels. h. Muscle cells cut across.

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  Cross-section histology of small intestinal villi of the human terminal ileum.

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  MicroCT-based volume projection of the jejunal mucosa of a chicken. Virtual volume block with vertically truncated villi in oblique view. Scalebar = 0.2 mm.

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  MicroCT-based volume projection of the jejunal mucosa of a chicken. Virtual horizontal cut through villi. Scalebar = 0.2 mm.

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  Microvilli (shaggy hair) show electron dense plaques (open arrow) at their apices.

See also

In Spanish: Vellosidad intestinal para niños