Epithilia are cells from the glandular and connective tissues. The name represents a collective term, which is also known as “surface covering cell layer”. In this context, the tissue exhibits important functions, which can be affected by various diseases.
What are epithilias?
Epithilias can consist of one or more layers of cells. Different cell types exist and are differentiated based on various characteristics. For example, multilayered epithelial cells can be found in the esophagus and vagina, whereas single-layered epithilia are localized in the gastric and intestinal mucosa. Multi-layered epithelial cells are found in the respiratory tract, transitional epithelium in various elements of the urinary system. All body surfaces are surrounded by epithilia on the inner and outer sides in humans. Only the joint capsules as well as the bursa are excluded from this rule. The cells represent another type of tissue besides muscle, nervous and connective tissue. The epithelial tissue normally contains only a small amount of blood vessels. It is important in the overall health of the skin.
Anatomy and structure
Epithelial cells are separated from connective tissue by a basement membrane, which is composed of certain proteins. Adjacent epithelial cells, on the other hand, are in contact with each other throughout. If a single cell is observed, it is noticeable that it contains only a very small amount of intercellular substance. Epithelial cells are polarized, they can partially distinguish directions from each other. Decisive for this property is their location: either epithelial cells are located between body and air or within the organism between connective tissue and lumen. In principle, they are responsible for always separating two areas from each other. Thereby the outer side is called apical. It tends to the external part, like to the skin or the lumen. The basal side, on the other hand, is in contact with the tissue, which is located below the epithelial tissue. In this case, the connection is made through another membrane.
Function and tasks
The functions and tasks of epithelial cells vary widely and depend on several factors. Epithelial cells within glandular tissue have differentiated steps of work than cells located in surfaces. In addition, the surrounding organ also determines the tasks of the tissue. Nevertheless, the spectrum of tasks can be divided into protective, sensory, secretory, as well as transport function. The protective function is especially obvious in the case of the skin surface: in order to prevent injuries and cracks, the skin must be elastic and firm. In addition, the epithelial cells ensure that the connective tissue does not detach from the skin, but is firmly anchored in it. At the same time, organs are sealed by the epithelial cells. Only in this way is it possible for the stomach contents to remain in the stomach and the food residue in the intestine. But also with regard to internal organs, the tissue is responsible for protecting against mechanical stimuli. In the context of sensory function, it is noticeable that the majority of cells in sensory organs can be localized within epithelial tissue. Here, epithelial cells are useful in that they can connect internal and external elements. Accordingly, epithelial cells help with vision, smell, and taste. They are found in the human retina, on the back of the tongue, and in the olfactory mucosa. In addition, they transmit mechanical stimuli such as temperature and pain sensations to the brain. Via very fine hairs, so-called cilia, the epithelial cells are also able to remove foreign bodies. The body’s own secretion in the form of sweat or other substances is carried out by glandular epithelial cells. In addition to secretions such as tears, hormones are also secreted here, such as thyroid hormones. Epithelial cells thus perform numerous and important tasks. If their function is restricted, various symptoms and complaints can occur. That is why a speedy visit to the doctor is recommended.
Diseases
Different viruses and bacteria have the potential to invade and damage epithelial tissue. In viral diseases, this often involves infection with the herpes virus. Herpes viruses can cause cells to swell and accumulate fluid.A high level of leukocytes can often be detected in this. Bacterial infections often occur via streptococci and staphylococci. The invasion and multiplication of the bacteria can cause inflammation. In this way, wound roses develop, for example. The bacteria get into the epithelial tissue in different ways and cause swelling and pain due to an area-wide inflammation. The following treatment also depends on the time of diagnosis. Even if this could be successfully completed, a recurrence of the disease cannot be ruled out perfectly. Apart from pathogens, tumors can also affect the epithelial layer. These are benign or malignant changes in the tissue. They can be carcinomas, but also basaliomas. While basaliomas do not metastasize, they still have the potential to spread to surrounding tissue and cause further damage. The epithelium surrounds various organs. If disease occurs in the vessels that are supplied by the epithelial cells, vascular epithelial disease may appear. For example, capillary loops of the skin can damage the basement membrane and be responsible when blood enters the epithelial tissue. In addition, autoimmune diseases can cause dissolution of the epithelial layers. This can lead to allergies, itching, wheals or swelling. Immunologic reactions may be responsible for the separation between epithelium and underlying tissue.
Typical and common skin disorders
- Vitiligo (white spot disease).
- Skin rash
- Skin fungus
- Rosacea (rosacea)
- Systemic lupus erythematosus (SLE)
- Skin cancer
