Structural Naming of Epithelial Tissue - Online Tutor, Practice Problems & Exam Prep

Human epithelial tissue is categorized into eight main types, primarily using a two-word naming system. The first word indicates the number of cell layers: "simple" for one layer and "stratified" for multiple layers. The second word describes cell shape: "squamous" (flat), "cuboidal" (cube-like), or "columnar" (tall and narrow). Notable exceptions include pseudostratified columnar, which is simple, and transitional epithelial tissue, which is stratified. Understanding these classifications is essential for studying tissue structure and function in anatomy and histology.

Structural Naming of Epithelia

So now that we've covered the characteristics and functions of epithelial tissue, in this video, we're going to begin our lesson on the structural naming of epithelial tissue. Structurally, humans have 8 main types of epithelial tissue. Most of them, in fact, 6 out of 8 of them are named using a two-word naming system, where both the first and the second words of this system reveal structural characteristics of the tissue. The first word of this two-word naming system indicates the number of cell layers in the tissue, specifically whether the tissue has just one layer of cells or if it has multiple layers of cells.

The second word of this two-word naming system indicates the cell shape. Let's take a look at our image below to start piecing things together. To orient you with this diagram, notice across the top, we have the first word of our two-word naming system and across the side, the second word. Below, we have the 2 naming exceptions to this system. We'll talk about these exceptions a little later toward the end of this video. For now, let's focus on these two words. Once again, the first word will tell us the number of cell layers—either "simple" for one layer or "stratified" for multiple layers.

For the second word, there are three possibilities: "squamous," "cuboidal," or "columnar." The term "squamous," meaning scales in Latin, suggests that the cells are flat. If we look at the diagram, you can see these flattened cells, somewhat reminiscent of fried eggs. "Cuboidal" implies that the cell shape is cube-like, as shown in the diagram. Finally, "columnar" indicates that the shape of the cells is tall and narrow, like a column, which is evident in how the cells appear elongated in the diagram.

We can pair first words with second words to describe the epithelial tissues. For instance, pairing "simple" with "squamous" would suggest one layer of flat cells, as shown here. Simple squamous epithelial tissue will appear with one layer of these flat cells. Now, consider "stratified" paired with "squamous", which would indicate multiple layers of these flat cells. This arrangement shows many cell layers, each appearing flat.

Remember, for stratified tissues, the naming focuses on the cell shapes at the apical surface, facing the open space. We can continue to match these words to define other epithelial tissues. Pairing "simple" with "cuboidal" results in one layer of cube-shaped cells. "Stratified" with "cuboidal" reveals multiple layers of cube-shaped cells. Similarly, "simple" with "columnar" delivers one layer of tall, column-shaped cells, and "stratified" with "columnar" multiple layers of column-shaped cells.

This leads to six types of epithelial tissues: simple squamous, simple cuboidal, simple columnar, stratified squamous, stratified cuboidal, and stratified columnar. The two exceptions are "pseudostratified columnar", a simple epithelial tissue with seemingly multiple layers but actually just one, and "transitional epithelial tissue", a stratified type with multiple layers of cells. The term "pseudo" indicates a false or fake layer, thus explaining the presence of only a single layer in pseudostratified columnar epithelial tissue.

Moving forward in our course, we will delve into each of these 8 epithelial tissues in separate videos, discussing their characteristics and features extensively. This concludes our brief lesson on the structural naming of epithelial tissue. I'll see you all in our next video.

Structural Naming of Epithelial Tissue Example 1

So here we have an example problem that's asking, what are the names of the following tissues? And notice down below, we have tissue a over here and tissue b over here. And so recall from our last lesson video that most epithelial tissue is going to be named using a two-word naming system, where the first word will indicate whether there's just one or multiple layers of cells, and the second word will indicate the cell shape. And so looking at this tissue a over here on the left, we can clearly see that there are multiple layers of cells. In fact, it looks like there are 3 layers of cells.

And so, we know that there are multiple layers of cells because not all of the cells are touching the basement membrane, which is at the bottom. And so, because there are multiple layers of cells here, we know that the first word must be stratified, which indicates that there are multiple layers of cells. Now, the second word we know is going to indicate the cell shape. And when we're looking at stratified tissue that has multiple layers, it's best to look at the shape of the cells that are closest to the apical surface. And so, recall that the apical surface of the tissue is going to be facing the open space.

And so, that would be the open spaces up above here because the basement membrane is down below. And so, the cells closest to the apical surface would be up here and notice that they take this box-like or cube-like shape, which tells us that the second word is going to be cuboidal. And so, what we have here is stratified cuboidal tissue. So, now moving on to tissue b over here, notice that we have just a single layer of cells. And we can tell that because all of these cells appear to be touching the basement membrane that we see down below.

And so, because all of the cells are touching that basement membrane, we know that we have one layer of cells and so the first word must be simple, indicating that there's just one layer of cells. And so now we want to focus on the second word, which is going to indicate the cell shape And notice looking at the shape of these cells that they are very long and narrow and they look column-like. And so that means that the second word here is going to be columnar. And so this tissue b here is going to be simple columnar tissue. And so that here concludes this example and we'll be able to get some practice applying these concepts moving forward.

So I'll see you all in our next video.

You look at a slide under the microscope & the tissue has a single layer of cells next to an open surface. The indicated cells are roughly as tall as they are wide. How would you identify these cells?

• A. Simple cuboidal epithelium. 
• B. Simple squamous epithelium.
• C. Stratified cuboidal epithelium.
• D. Stratified squamous epithelium.

Of the following tissue types, which is likely to be the thinnest overall? 

• A. Stratified cuboidal epithelium. 
• B. Simple columnar epithelium.
• C. Stratified columnar epithelium.
• D. Simple cuboidal epithelium.

True or false: stratified squamous epithelium is thicker than simple squamous epithelium. 

• A. True.
• B. False.

You look at a slide under the microscope & the tissue has a double layer of cells next to an open surface. The indicated cells are tall and narrow. How would you identify these cells? 

• A. Stratified columnar epithelium.
• B. Stratified cuboidal epithelium.
• C. Simple columnar epithelium.
• D. Stratified squamous epithelium.

Here’s what students ask on this topic:

What are the main types of epithelial tissue based on structural naming?

Human epithelial tissue is categorized into eight main types using a two-word naming system. The first word indicates the number of cell layers: 'simple' for one layer and 'stratified' for multiple layers. The second word describes the cell shape: 'squamous' (flat), 'cuboidal' (cube-like), or 'columnar' (tall and narrow). The six main types are simple squamous, simple cuboidal, simple columnar, stratified squamous, stratified cuboidal, and stratified columnar. Additionally, there are two exceptions: pseudostratified columnar, which is actually a type of simple epithelial tissue, and transitional epithelial tissue, which is a type of stratified epithelial tissue.

How does the two-word naming system for epithelial tissue work?

The two-word naming system for epithelial tissue reveals structural characteristics. The first word indicates the number of cell layers: 'simple' means one layer, and 'stratified' means multiple layers. The second word describes the cell shape: 'squamous' indicates flat cells, 'cuboidal' indicates cube-like cells, and 'columnar' indicates tall, narrow cells. For example, 'simple squamous' refers to a single layer of flat cells, while 'stratified cuboidal' refers to multiple layers of cube-shaped cells. This system helps in identifying and understanding the structure and function of different epithelial tissues.

What are the exceptions to the two-word naming system in epithelial tissue?

There are two exceptions to the two-word naming system in epithelial tissue: pseudostratified columnar and transitional epithelial tissue. Pseudostratified columnar appears to have multiple layers but is actually a type of simple epithelial tissue with just one layer of cells. The term 'pseudo' means false, indicating that it falsely appears stratified. Transitional epithelial tissue, on the other hand, is a type of stratified epithelial tissue with multiple layers of cells. It is unique because it can stretch and change shape, commonly found in the urinary bladder.

What is the difference between simple and stratified epithelial tissue?

The primary difference between simple and stratified epithelial tissue lies in the number of cell layers. Simple epithelial tissue has only one layer of cells, making it ideal for functions like absorption, secretion, and filtration. Examples include simple squamous, simple cuboidal, and simple columnar. Stratified epithelial tissue, on the other hand, has multiple layers of cells, providing more protection against abrasion and wear. Examples include stratified squamous, stratified cuboidal, and stratified columnar. The naming system helps in identifying the specific type and function of the epithelial tissue.

How can you identify squamous, cuboidal, and columnar cells in epithelial tissue?

Squamous, cuboidal, and columnar cells can be identified based on their shapes. Squamous cells are flat and thin, resembling scales or fried eggs, and are often found in tissues where diffusion or filtration occurs. Cuboidal cells are cube-shaped, with equal height, width, and depth, and are typically found in glandular tissues and ducts. Columnar cells are tall and narrow, resembling columns, and are commonly found in the digestive tract lining, where they aid in absorption and secretion. Recognizing these shapes helps in identifying the specific type of epithelial tissue and its function.