Every organ and cells of the body comprise smaller structures to help them with their functions and to maintain the health of every individual. The intestines in a human body are responsible for the digestion and finally a breakdown of the food particles consumed.
The nutrition absorption that occurs in the small intestines is the most important function that helps to sustain life. Like all other organs, they also have small structures that help with their smooth functioning like villi and microvilli. Though the names of these structures are similar, they are different in every other aspect.
Villi vs Microvilli
The main difference between Villi and Microvilli is that villi are found only with the small intestines whereas microvilli are found on the cell membranes of many organs of the body, along with the small intestines.
Villi are big finger-like projections in the walls of the small intestines that extends to the lumen. They have a length of 0.5 to 1.6 millimetres. Their main function is to increase the surface area for absorption of 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 in size.
Comparison Table Between Villi and Microvilli
| Parameters of Comparison | Villi | Microvilli |
| Size | It is big | Is smaller than 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 intestines and many other cell membranes |
| Occurrence | They occur in the small intestines and extend to the lumen of this 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 but also 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 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 that is 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 a digestive enzyme on their surface.
Each villus has a layer of microvilli over them forming a brush border. They also have blood vessels and lymph vessels in between to help in the transmission of the absorbed nutrients, minerals and electrolytes.
What is Microvilli?
Microvilli are a large number of minute projections that occur on the surface of 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, is measured in micrometres. They approximately measure 1 micrometre in length.
- Villi are finger-like structured projections whereas microvilli are minute projections that are present in large numbers on cell membranes.
- Villi are only found on the cell membranes of walls on the intestines. On the other hand, microvilli are found on top of the villi, forming layer as well as in many other cell membranes of the body.
- Villi occur at 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. Whereas, along with increasing the surface area, microvilli are also used for many other functions and these functions 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.
Conclusion
Microvilli and villi are structures that are found in the small intestines and are often mistaken for one another. Though they both have similar structures, it is important to know the difference because they have different functions.
Villi are finger-like structures found in the small intestines. Their main function is the absorption of nutrients provided by the food particles that enter the small intestines. They are layered with bundle fo microvilli forming brush borders.
Microvilli are cellular structures, unlike villi and are found on the cell membrane of many epithermal cells. They have different functions depending on the cell membrane they are present on. Microvilli also have a size of just 1 micrometre and are usually present in large numbers.
Microvilli and villi are both present in the small intestines, but the difference is that microvilli are also present in other cell organelles along with the walls of the small intestines.
References
- https://www.ncbi.nlm.nih.gov/pmc/articles/pmc1166384/
- https://onlinelibrary.wiley.com/doi/abs/10.1002/jemt.1060160107