Every organ and cell of the body comprises smaller structures to help them with their functions and maintain every individual’s health. The intestines in the human body are responsible for digestion and finally a breakdown of the food particles consumed.
The nutrition absorption in the small intestines is the most important function that helps sustain life. Like all other organs, they also have small structures that help their smooth functioning, like villi and microvilli.
Though the names of these structures are similar, they are different in every other aspect.
Key Takeaways
- Villi are finger-like projections found in the small intestine, while microvilli are even smaller projections on the surface of each villus.
- Villi increase the surface area of the small intestine for nutrient absorption, while microvilli increase the surface area even further.
- Villi are visible to the naked eye, while microvilli can only be seen under a microscope.
Villi vs Microvilli
Vali is finger-like projections in the lining of the small intestine that increase the intestine’s surface area for efficient absorption of nutrients. Microvilli are small finger-like projections found on the surface of certain cells, made up of bundles of actin filaments.
Villi are big finger-like projections in the walls of the small intestines that extend to the lumen. They have a length of 0.5 to 1.6 millimetres. Their main function is to increase the surface area to absorb the various nutrients that reach the small intestines.
Microvilli are cellular structures that are not only found on top of villi but also on many other organs to help them with their functions. They are found only on the cell membrane of epithermal cells. Microvilli are minute projections, much like the villi, but smaller.
Comparison Table
| Parameters of Comparison | Villi | Microvilli |
|---|---|---|
| Size | It is big | It is smaller than the villi |
| Structure | They have a finger-like projection structure | They are a large number of minute projections |
| Found in | They are found on the walls of intestines only | They are found on the walls or cells of the intestines and many other cell membranes |
| Occurrence | They occur in the small intestines and extend to the lumen of these intestines. | They only occur on the cell membranes of epithermal cells |
| Function | Increase the surface area for absorption | They are used for increasing the surface area for diffusion and many other functions like absorption. |
| Formation | They do not form anything but have a layer of microvilli on top, forming a brush border. | They bundle up to form a brush border. |
What is Villi?
The small finger-like structures found on the walls of the small intestines are called villi. They are only present in the small intestines and are found to extend to the lumen of these intestines.
Since their main function is to increase the surface area for the absorption of nutrients in the small intestines, they are formed by folding the mucosa on the walls of these intestines.
Though they mainly absorb nutrients, they also absorb electrolytes and minerals. They are not permeable to diffusion. They also have a layer of digestive enzymes on their surface.
Each villus has a layer of microvilli over them, forming a brush border. They also have blood vessels and lymph vessels to help transmit the absorbed nutrients, minerals and electrolytes.
What is Microvilli?
Microvilli are many-minute projections that occur on the surface of the cell membranes of many epithermal cells. Though they are found to be forming a layer of brush border on villi, they are also found on many other organs.
Their main function is increasing surface area for diffusion, but their function depends on the cell membrane they are present on. So their functions also include absorption, secretion and forming brush borders.
The boundary of microvilli is formed with the plasma membrane, and the inside is filled with cytoplasm. This also means that microvilli are cellular structures, whereas villi are not. But they are microscopic; therefore, they do not contain any other cell organelles.
The core of each microvillus contains cross-linked actin filaments.
Main Differences Between Villi and Microvilli
- Villi have a large size when compared to microvilli. Villi have a length of 0.6 to 1.6 mm, whereas microvilli, as the name suggests, are measured in micrometres. They measure approximately 1 micrometre in length.
- Villi are finger-like structured projections, whereas microvilli are minute projections in large numbers on cell membranes.
- Villi are only found on the cell membranes of the walls of the intestines. On the other hand, microvilli are found on top of the villi, forming layers as well as in many other cell membranes of the body.
- Villi occur in the small intestines only. They are found to be extending to the lumen of the small intestines. Microvilli make occurrence at the cell membranes of the only epithermal cell.
- The only function of villi is to increase the surface area of absorption in the intestines. Besides increasing the surface area, microvilli are also used for many other functions, which depend on the membrane on which they are present.
- The microvilli bundle up to form brush borders on top of the cell membranes where they are present. The villi do not form such borders but rather have a bundle of microvilli on top of them, forming these brush borders.
- https://www.ncbi.nlm.nih.gov/pmc/articles/pmc1166384/
- https://onlinelibrary.wiley.com/doi/abs/10.1002/jemt.1060160107
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
