Endothelial cells cover the inner surface of the blood vessel, and epithelial cells cover the inner surface of the internal organs. The epithelial cells also cover the outer surface of the human body. If a large number of epithelial cells are found in the urine during urine testing, it indicates a urinary tract infection.
The endothelial cells and epithelial cells that make up the tissue are derived from the epithelium, but the two are different in location, structure, and function (as the table). In addition, both cells form the interface between the inner and outer environments. Endothelial cells are located “inside” the body, such as the interior of blood vessels, while epithelial cells are often described as covering the “outside” of the body, such as the outer layer of the skin (epidermis, epidermis).
Comparison of endothelia cells and epithelial cells:
|Items||Endothelial cells||Epithelial Cells|
|Location||Endothelial cells form endothelium, a thin layer that covers the inner surface of the blood vessel. Briefly, the cells cling to the blood vessel wall. Therefore, the inner wall of the entire circulatory system is covered by endothelial cells. These cells form the interface between the blood vessel wall and the blood. They close to the inner surface of the heart. They are a thick layer of single cells.||The epithelial cells that make up the epithelial tissue cover not only the outer surface of the body, but also the outer surface of all internal organs of the body. For example, the epidermis of the outermost layer of the skin is the epithelial cell. The skin on the surface is thus covered by epithelial cells, which provide a protection for the body. Epithelial cells also cover the surface of internal organs, such as the liver, stomach, intestines, lungs, urethra, bladder, and the like. In other words, epithelial cells cover the surface and internal tissues of the body.|
|functions||Endothelial cells covering the vessel wall regulate blood flow in the blood vessels, which release NO. NO is a vasodilator that promotes blood circulation and helps control blood pressure. Endothelial cells can also secrete a variety of proteins that cause blood disorders, but they also stop bleeding. The inside of the glomerulus contains endothelial cells, which act to filter blood.||The epithelial cells that make up the skin protect the subcutaneous tissue from damage, bacterial intrusion, dangerous chemicals, and avoid excessive loss of moisture. When necessary, the skin’s epithelial cells also secrete sweat to regulate body temperature. Epithelial cells covering the pancreas secrete enzymes to promote digestion. In addition, epithelial cells on the surface of the small intestine absorb nutrients from the digested food. Epithelial cells on the surface of the respiratory tract form mucous membranes that secrete mucus to prevent inhaled bacteria and viruses from entering the lungs. Specialized epithelial cells are secreted on organs that are in contact with nerve endings such as skin, nose, tongue, eyes, etc., which recognize sensory stimuli. In summary, the main functions of epithelial cells involve secretion, absorption, and protection.|
|Features||The endothelial cells that make up the endothelial tissue are monolayer structures, and water molecules and oxygen molecules easily pass through the endothelial cells and enter the tissues surrounding the endothelial cells. In addition, endothelial cells lack a packed epithelial morphology, and there are gaps between endothelial cells, which contribute to the passage of liquids and the diffusion of substances.||The epithelial cells that make up the epithelial tissue have a variety of structures to protect the body from the external environment. Epithelial cells are tightly bound, similar to bricks, with few gaps between cells.|
|Intermediate Filaments||Some proteins, referred to herein as intermediate filaments, support the cells and form the shape of the cells. Simply speaking, the intermediate filaments provide the cellular structure. Endothelial cells contain vimentin filaments.||Keratin filaments provide the structure of epithelial cells.|
|Surface layer||The surface of endothelial cells is a non-thrombogenic, soft surface that does not coagulate during normal blood circulation.||Epithelial tissues composed of different types of epithelial cells exhibit irregular papillary projections.|
Schematic diagram of endothelial cells (Figure 1) and epithelial cells (Figure 2):
Endothelium is a kind of epithelium. The endothelial cells are distributed on the inner surface of the blood vessels. In the lumen, the endothelial tissues form the interface between the circulatory system or the lymphatic system and other parts of the blood vessels. The structure is as follows:
Figure 1. Schematic diagram of endothelial cells
Figure 2 shows the morphology of epithelial cells. Epithelial cells can be arranged in a single layer of cell structure, or in two layers, or even a multi-layered cell structure. As shown in Figure 2, all glands are composed of epithelial cells. The function of epithelial cells includes secretion, absorption, protection, and transmembrane transport.
Figure 2. Morphology of epithelial cells