 epithelial tissues, types and functions, first the contents, epithelial tissues, basement membrane and the functions of epithelial tissues. So first the definition of epithelial tissues, epithelial tissues are actually the renewable sheets of cells which covering the outermost layer or surface of different organs or they are lining the inner body parts. So students if we talk about epithelial tissues, the word epica means the outer one, the upper one. And thelium is called a layer. Epithelial tissues are basically the type of cells or tissues which line the outermost boundary of different body parts. And similarly the tubular portions of the body with the outermost boundary like the stomach or the lungs or the tubular portions of the body with the hollow spaces, the tubular portions of the body are also lined by the epithelial tissues. So if we look at the example of epithelial tissues, our skin is made up of epithelium, the outermost layer of our skin is covering the entire body. So the visceral organs like the internal body, the heart, the lungs, the kidneys, the outer layer that is also epithelium, if there is space or cavity in it, the lining of the cavity is basically epithelial tissues. Epithelial tissues, the special thing is that they are continuously dividing cells. So the cells on the upper epithelium, if the slough of the upper epithelium is removed, especially the digestive tract epithelium, it is continuously removed. When we eat food, the cells of the digestive tract come along with our food, the cells of the membrane are removed. So it means that the epithelium is removed from the upper epithelium and the new epithelium is removed from the lower epithelium. The other cells that separate the epithelium from the lower epithelium, the boundary that is the basement membrane, the basement membrane is basically epithelium and the endothelium is the other cells that separate it from the connective tissues. In the diagram, you can see that the long columnar cells, column-like pink-colored cells are epithelial tissues and the lower epithelium is the layer of the connective tissues. The lower epithelium is the base of the membrane and the lower epithelium is the base of the membrane. So the base of the membrane is basically a matrix, which is a different non-cellular material that usually separates the epithelium from the other types of tissues. What are the functions of epithelium? If we talk about the functions of epithelium, we should first know where the epithelium is. Number one, epithelium is the layer of the outer most of the body. Now when the outer most is the layer, the functions of the skin will perform on the epithelium. What are the functions? It is a sensation. As we have touched, we can feel that there is a sensory organ in the skin, the part of the sensation that will perform on the epithelium. Similarly, our test words, the relevant work of the test, if we look at the internal body organs, we can see that the work of the intestine is to absorb the nutrients. The small intestine is the large intestine, they are absorbing. So if we look at the collective leg, there are many functions of epithelium, which if we have a few functions, we have absorption, then transportation, then excretion, then protection, then sensory functions and the secretion. Now if we look at the work of protection, it is skinning. Similarly, the secretion is our glands, digestive glands, like we have salivary glands, there are glands in the stomach or the glands of the intestine, all of these glands are basically the modifications of epithelium. Similarly, excretion, in the sweat gland, there are many toxic materials, not salt that excrete from the body. So sweat gland is basically an modification of epithelium, which is performing on the function of excretion. So similarly, transportation. In transportation, if we look at blood vessels, arteries, capillaries and veins, which when the blood flows, the lines of the blood vessels are actually the epithelial in nature and the epithelium is formed. Here we have some diagrams. In this, the top is the diagram of nephron. In this, this tubular structure, the nephron basically is made up of the single layer of epithelium of the cell, which has different functions, in the kidney. In its important functions, one is the urine, whose formation is that the urine will travel through the nephron and go into the urinary tract. Kidneys. So the second function is in the intestine. The second top, which you can see in the picture, is basically the structure of the small intestine. It is called cross-section. So the small intestine is making microvillage and village in epithelium, and its function is absorption. If you look at the bottom like this, then there are gills. Gills are for gaseous exchange. What are gills basically? There is epithelium on it. In this, we have the lungs of the kidneys, which we are looking at, which has to play a role in gaseous exchange. In this, in the next diagram, you have two test birds. The test bird's sensory function is epithelium. Similarly, in the next cross-section, you are looking at the wall of the stomach. What are the gastric glands on the stomach basically? They are epithelium. They are made up of epithelium, which gives secretion.