There are two kinds of projections on the plasma membrane. They are called cilia and microvilli. These can also be found on the outside of the epithelial cells.
But microvilli and cilia are not the same thing because they do different things inside the cell. Also, each of these has a different location and structure. Read on to learn more about how they are different.
What is Cilia?
Cilia are long extensions of the plasma membrane that look like hair and have microtubules in the middle. The length of a cilium is usually between 5 and 10 m, and its width is about 0.2 m.
These structures can move and beat in one direction to push the tangled particles away from the surface. Some specialized cells, like the sensory cells in the ear of a vertebrate, also have cilia.
These cilia are surrounded by actin-based stereocilia and are important for providing the first sensory information for hearing.
The core of the cilium is made up of microtubules that are always arranged in what is called (9+2) orientation, or longitudinal orientation. 9+2 means that each cilium’s core is made up of nine doublet microtubules around the outside and two single microtubules in the middle.
The basal body is the part from which each cilium grows directly. The structure of the microtubules in the basal body is different.
In the cilium core, fine microtubules are spread out around the edges. In the basal body, there are nine microtubule triplets, but there are no microtubules in the middle.
What is Microvilli?
Microvilli are long projections from the plasma membrane that look like fingers and are made up of thin microfilaments in the middle.
Bundles of these microfilaments are held together by proteins called villin and fimbrin that link to each other. The main purpose of the microvilli is to take in certain chemicals.
Cells make microvilli mainly to increase the surface area for absorption (the surface of the intestine), move nutrients that have been taken in, and help break down carbohydrates.
A microvillus is about 0.5 to 1 m in length and about 0.1 m in width. Brushboards are made up of surfaces with a lot of microvilli. You can see these brush borders on the inside of many epithelia, including the intestine, which is designed to absorb.
Key Differences Between Cilia and Microvilli
|Structure||Cilia are made up of microtubules that are coated by a plasma membrane. Each cilium makes an axoneme structure in which nine pairs of microtubules form an outside ring with two central microtubules.||Microvilli are small finger-like projections that are 90nm in diameter and 1mm in length. In microvilli, bundles of parallel actin filaments are held together through a cross-linking protein, fimbrin, and villin. These proteins held them in a bundle.|
|Function||The main function of cilia is to move water relative to the cell. Multiple cilia move In a rhythmic motion and keep the internal passageways free from any kind of foreign agent or mucus.||Microvilli on the surface of epithelial cells increase the cell’s surface area and facilitate the absorption of water molecules and ingested food.|
|Types||Cilia can be divided into two types: motile and non-motile cilia. Non-motile cilia are also known as primary cilia.||Microvilli are divided into three types according to their function: absorptive microvilli, microvilli for immune cells, and microvilli for inner ear cells.|
|Location||Motile cilia are located on the epithelial cells of several organs like the lungs, digestive system, and trachea. And non-motile cilia can be found on olfactory neurons.||A thousand amounts of microvilli can be found on the apical surface of human small intestine cells. It can also occur in cells of taste buds and cells of the inner ear.|
|Glycocalyx||Cilia shafts are not covered with glycocalyx. Each cilium is covered with a cell membrane and originates near a basal body.||Microvilli are covered with glycocalyx, which contains peripheral glycoproteins to attach themselves to the membrane.|
|Ultra Structure||In the ultrastructure of cilia, cilia show a few subregions, which are transition zones to link these cilia to a basal body.||In the ultrastructure of microvilli, each microvillus consists of a bundle of actin filaments, which work as its structural core.|
Cilia vs. Microvilli Similarities
- Cilia or microvilli both are microscopic structures that are present in the plasma membrane.
- Both grow outside of the cells
- Both consist of protein fiber
Cilia vs. Microvilli Pros and Cons
Cilia Pros and Cons
Pros of Cilia
- Motile cilia in the respiratory tract and inner ear move in a rhythm that keeps the inner channel free of dirt and mucus.
- Cia are also important for replication and the cell cycle in both people and animals.
Cons of Cilia
- If, for some reason, the cilia don’t work well, bacteria can stay in the respiratory system and cause an infection.
- Damage to the cilia can make it hard to breathe and lead to problems with the lungs.
Microvilli Pros and Cons
Pros of Microvilli
- Microvilli can make a cell’s surface area bigger, which makes it take in and send out more things.
- By making the surface area of the intestine bigger, microvilli can help the body absorb more nutrients and other substances.
Cons of Microvilli
- When microvilli are damaged, the intestines don’t work right. This can lead to diarrhea and other problems.
- In people with celiac disease, eating foods with gluten can cause the immune system to attack the villi and microvilli in the intestines.
Both cilia and microvilli are protrusions made by the plasma membrane. Compared to microvilli, cilia are longer and have more mass.
Cilia can help move the whole cell or things like microbes, dirt, and mucus over the surface of the cell in a rhythmic way. On the other hand, microvilli don’t move.
They make the surface area of the intestine bigger, which makes it easier for the body to absorb nutrients. So, the main difference between cilia and microvilli is how they work.