Villus

Villus is a type of small projection that is found in the lining of the small intestine. It is part of the intestinal mucosa and plays a crucial role in the absorption of nutrients from the intestine.

Structure

Each villus is approximately 0.5-1.6 mm in length, and has many microscopic microvilli projecting from the cells of its epithelium. This structure increases the surface area of the intestine and facilitates the absorption of nutrients.

The villi are covered with a single layer of columnar epithelial cells, which are responsible for the absorption of nutrients. These cells have a brush border of microvilli, which further increases the surface area for absorption.

Inside each villus, there is a network of capillaries and a central lacteal, which is a lymphatic vessel. The capillaries absorb most of the nutrients, while the lacteal absorbs fats and fat-soluble vitamins.

Function

The main function of the villi is to increase the surface area of the intestine, which allows for more efficient absorption of nutrients. The villi and microvilli can increase the surface area of the small intestine by 30 times.

The columnar epithelial cells on the villi have enzymes on their surfaces that break down nutrients. Once the nutrients are broken down, they can be absorbed into the capillaries and lacteal.

Clinical significance

Damage to the villi can lead to malabsorption of nutrients, which can cause various health problems. For example, in celiac disease, the immune system damages the villi in response to gluten, leading to malabsorption of nutrients.

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