The Intestinal Villi Explained || Absorption

One of the functions of the small intestine is to take digested food molecules from the digestive system and transfer them into the blood, so that they can be transported to the parts of the body that need them. The digested food in the small intestine contains molecules such as glucose from the digestion of starch, amino acids from proteins, fatty acids and glycerol from lipids, as well as lots of other essential materials. These must be absorbed into the blood stream so that your body can use them.

The walls of the small intestine are lined with intestinal villi. And FYI, it’s one villus, many villi. Villus is singular, villi is plural.

The villi increase the surface area of the wall of the small intestine to maximise the rate of absorption of digested food.

Picture one flat line between points A and B, and image that material has to transfer across it. If you measure this line (the length of the surface for materials to transfer) you’ll see its 10 cm long. Now picture a line between the same points A and B, but on this new line there are finger-like projections all the way along. If you measure along the surface of this line, you’ll find it’s far longer than 10 cm. The version with the projections has a larger surface area, meaning more material can be transferred in the same amount of time.

Here’s a simplified diagram showing a single villus. Food molecules are transferred from the central space in the small intestine into the villi.

The epithelial cells of its lining have many microvilli on them. This further increases the surface area.

Villi have a good blood supply constantly flowing in and out through many blood capillaries. Most materials are transferred to the blood capillaries. There’s also a structure inside each villus called a lacteal, and the products of lipid digestion are absorbed into this part, and from there they’ll also eventually reach the blood stream at a different point.One of the functions of the small intestine is to take digested food molecules from the digestive system and transfer them into the blood, so that they can be transported to the parts of the body that need them. The digested food in the small intestine contains molecules such as glucose from the digestion of starch, amino acids from proteins, fatty acids and glycerol from lipids, as well as lots of other essential materials. These must be absorbed into the blood stream so that your body can use them.

The walls of the small intestine are lined with intestinal villi. And FYI, it’s one villus, many villi. Villus is singular, villi is plural.

The villi increase the surface area of the wall of the small intestine to maximise the rate of absorption of digested food.

Picture one flat line between points A and B, and image that material has to transfer across it. If you measure this line (the length of the surface for materials to transfer) you’ll see its 10 cm long. Now picture a line between the same points A and B, but on this new line there are finger-like projections all the way along. If you measure along the surface of this line, you’ll find it’s far longer than 10 cm. The version with the projections has a larger surface area, meaning more material can be transferred in the same amount of time.

Here’s a simplified diagram showing a single villus. Food molecules are transferred from the central space in the small intestine into the villi.

The epithelial cells of its lining have many microvilli on them. This further increases the surface area.

Villi have a good blood supply constantly flowing in and out through many blood capillaries. Most materials are transferred to the blood capillaries. There’s also a structure inside each villus called a lacteal, and the products of lipid digestion are absorbed into this part, and from there they’ll also eventually reach the blood stream at a different point.
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