Stratified squamous epithelium is a type of tissue that makes up skin layers and lines some body cavities and organs. Its structure makes it an excellent protective layer. Learn more about this tissue and take a short quiz at the end.
What is Stratified Squamous Epithelium?
When you think of the word tissue, you most likely imagine a colorful box sitting on your counter that you reach for after you sneeze. However, in the world of science, ’tissue’ tends to have an entirely different meaning. For example, you and I are made up of different types of tissue, but clearly not the kind in which you blow your nose.
In our bodies, cells with common structures and functions group together to form what we know as body tissue.Tissue in our bodies comes in four major types: epithelial, connective, muscle and nervous. In this lesson, we will examine one type that consists of flattened cells that are joined and stacked together, known as stratified squamous epithelium. This protective tissue can be found in several different locations in the body. Learn more as we closely examine this important layer.
Structure of Stratified Squamous Epithelium
In order to better understand this tissue type, we first need to break down this somewhat long and scientific name. Let’s first define epithelium. Epithelial tissue is made up of cells that are packed tightly together, forming one continuous sheet. Epithelium functions as both a cover and a lining for various parts of our body.For example, epithelial tissue covers our bodies in the form of skin layers.
Because the cells are stuck together so tightly, this tissue provides a mostly impermeable and highly protective barrier for our bodies. Epithelial tissue also lines some internal cavities and organs. This sheet of epithelial cells provides a smooth and continuous lining for these areas.
Now let’s look at the word squamous, which defines the shape of the actual cells that make up the tissue. Squamous means that the cells are flattened. You can think of them as being squashed. Let’s visualize this concept. Imagine taking a bag of soft fruit candies and squashing each one flat. You then stick them together side-by-side and end-to-end. This is a visual representation of a single sheet of squamous epithelium.
We are almost finished defining our long scientific term. We now have sheets of flattened cells that are packed closely together. So how does the word ‘stratified’ change our tissue? Stratified means that the cells are not only in one layer, but are stacked. Think of the word strata, meaning layered. Adding to our visual, you can take another bag of fruit candy, squash them, stick them closely together, and then stack that sheet onto your original. You now have a complete representation of stratified squamous epithelium.
Function of Stratified Squamous Epithelium
As mentioned previously, stratified squamous epithelium is found both covering and lining parts of the body.
The main function of this tissue type is protection, as it is typically found in areas that undergo significant wear-and-tear. This tissue is designed to withstand the abrasive sloughing off of the outer layer. Deeper layers simply produce more cells to replace those that have been lost. For example, our skin cells are constantly sloughing off, but are always replaced to keep the outer layer healthy.We find stratified squamous epithelium in two major types: keratinized and non-keratinized. The tissue that is keratinized contains the protein keratin, which can make the tissue tough and even scale-like.
Let’s take a look at our outer layer of skin, which contains keratinized stratified squamous epithelium. These cells are hardy and tough, able to withstand the abrasive nature of the outside world. The keratin also adds a waterproofing quality, essential to the health of our body. These qualities create a strong protective layer akin to the outer layer of a warm parka.
Internally, stratified squamous epithelium has no need to be keratinized because it is not in contact with the outside world. So in areas such as the esophagus and the lining of the mouth, we find non-keratinized tissue. However, this tissue still provides a protective layer against the harsh chemical environment caused by stomach acid. Additionally, there is a great deal of abrasion in our mouth and esophagus as we chew and swallow food.
Cells that slough off in these areas are also replaced by fresh cells.
Stratified squamous epithelium is a type of tissue found covering and lining parts of the body. In this tissue, cells are flattened, joined tightly together, and stacked. The major function of this tissue type is protection, as it is found in areas that undergo wear-and-tear.
This tissue comes in two types, keratinized and non-keratinized. We find keratinized tissue in our skin, and non-keratinized tissue internally.