Epithelial Tissue (Nursing)

00:00 So now let's discuss the different types of tissues that we find in the body. So, in general we're going to talk about the first 2 that I said before, connective tissue and epithelial tissue. So starting with epithelial tissue, these are going to be cells that are arranged in sheets and are very densely packed. There is very little extracellular matrix associated with epithelial cells. They usually have multiple types of cell junctions and this is important because again these cells are very tightly packed with each other and these cells are usually connected to each other by the cell junctions. If you are talking about certain types of cells especially ones that are covering or lining parts of the body, they are usually attached to a basement membrane or basically anchored to a surface in the body. Epithelial tissue does not contain blood vessels. It is an avascular tissue although it can contain some nerve cells. And finally, mitosis is going to occur frequently in epithelial tissue as there are numerous cells.

01:17 So the way that we classify the different types of epithelial tissue found in the body is by the way that these cells are arranged as well as the shape of the cells. So, in this way we have cells that are arranged in a single layer in which we call it a simple epithelium or if the cells are arranged in multiple layers we call it stratified. There is also a 3rd arrangement referred to as pseudostratified and this arrangement is a little different in that it is a single layer but it appears to be multiple layers because the nuclei of the cell are at different layers in this epithelial tissue. Now when it comes to arranging them by shape, we arranged them according to squamous which is a flattened type of cell, cuboidal which is like a box, and then columnar which is a longer type of cell. Each of these arrangements and shapes is important for the function of the tissue where these different types of epithelial cells are found. When naming epithelial tissue, we name them based on both of the categories. So we're going to use both the arrangement of the cells as well as the shape of the cells. So for example, in the epidermis of the skin we have multiple layers of epithelial cells. We referred to this as a stratified squamous epithelium. Whereas in the respiratory tract, we have a single layer of columnar cells and we referred to this as a simple columnar epithelium. So now, let's switch gears and talk about the different types of epithelia that we find in the body. There are 2 major types of epithelia in the body. You have surface epithelia also referred to as covering and lining epithelia and then you have glandular. Your covering and lining or surface epithelia are going to cover the outer portions of the body or the inner linings of certain organs in the body.

03:33 You're glandular epithelia are specialized for secretion and are going to secrete substances into the extracellular fluid.