Basic introduction of Epithelium

Epithelium is composed of dense epithelial cells and a very small amount of interstitial cells constitute the basic organization of animals. Generally connected to each other into a film-like, covered in the body surface, or lining the body of the hollow cavity surface, and body cavity surface. The arrangement of a single layer and multi-layer points. According to the characteristics of the function and structure can be divided into epithelial epithelial epithelium, glandular epithelium, sensory epithelium and other three categories. Which covered epithelium is generally referred to as theEpithelium, the most widely distributed.

Epithelial cells arranged closely, single or multi-layer, less interstitial cells. Covering the body surface or the body of the surface of the organs and the inner surface of the lumen, with protection, secretion, absorption and other functions.

Epithelium is the first occurrence of an organization in the organization, from the inside, outside the three germ layers formed. But mainly from the ectoderm and endoderm. Epithelial differentiation of the epithelium are: the epidermis and its derivatives (hair, gland, etc.), the body of all the openings (mouth, nose, anus) coated epithelium and nerve wall epithelium and so on. Endodermal epithelial epithelium: digestive tract, respiratory epithelium, gastrointestinal acinar and catheter; bladder and thyroid, parathyroid epithelium and so on. Mesodermal differentiation of the epithelium; cardiovascular system of the endothelium; lining in the abdominal cavity, chest, pericardial cavity and some organs on the surface of the skin, as well as kidney, adrenal cortex and gonadal epithelium. With protection, secretion and other functions.

General structural features of Epithelium

① cell tightly combined, there is a layer of cell cell coat cell coat is composed of cell membrane glycoprotein exposed sugar chain, with a strong adhesion, cell gap in the calcium ions, and cell-specific cell-to-cell Adhesion also plays an important role.

② obvious polarity, the two ends of the cell in the structure and function are different, one end of the surface to the body surface or body tube, cavity, capsule cavity surface, called the free surface; and free and the other end, called the base surface The Distribution of cells in different parts of the Epithelium free surface, often with different special structure and its specific function to adapt. Such as intestinal epithelium has a dense microvilli to expand the absorption surface; respiratory epithelium can swing the cilia, can be exposed to the invasion of dust and other foreign matter. Basal surface generally by a layer of basement membrane and its deep connective tissue connected. Some epithelial cells also have a base surface that also extends the cell surface area of the cell membrane or enhances the structure of the basement membrane.

③ generally no blood vessels, the nutrition from the deep connective tissue in the capillary through the base membrane supply. The basement membrane plays a selective role in the exchange of material between the blood and the Epithelium.

④ the distribution of nerve endings in Epithelium is more abundant, so feel more sensitive. For example, the skin's epidermis and bronchial epithelium are so.

Physiological regeneration of Epithelium

Physiological regeneration refers to the renewal of Epithelium in normal physiological conditions. Epithelium in the normal physiological state, the surface cells often die off the phenomenon, especially the epidermis and digestive tract epithelium. Due to frequent wear and tear, fall off, then by the lower degree of epithelial differentiation of cells through the mitotic way to fill, in order to maintain the number of epithelial cells constant and complete. The epithelium of the organs of the update rate, such as small intestine villi epithelium all updated once only 2 to 5 days; and pancreatic epithelium will take about 50 days.

Pathological regeneration of Epithelium

Pathological regeneration refers to the repair of Epithelium caused by inflammation, trauma and other pathological factors. If the epidermal injury of the skin is missing, the epithelial cells of the epithelial basal cells or the gland ducts of the wound edge are proliferated and exposed to connective tissue Area to move, become a single layer of flat cells, covering the wound. And then gradually increase the number of cells with the increase in the number of cells to regenerate the epithelial cells; gastrointestinal epithelial damage after shedding, by the adjacent parts of the normal epithelial cells or glandular epithelial cells split, began to cubic, And then gradually increased and become a single columnar epithelium, generally believed that the regeneration of glandular epithelium than the epithelium is weak.

Epithelium of metaplasia

The metaplasia of the Epithelium under certain physiological or pathological conditions, has been divided into mature tissue, the composition of cells can adapt to the changing conditions, in the shape, arrangement and function of the mutation, commonly known as histochemical or mutation. Epithelium metaplasia was more obvious. Such as long-term smokers or patients with chronic bronchitis, tracheal pseudocatalytic ciliated columnar epithelium can be transformed into a flattened epithelium; kidney stone parts of the epithelial transition, due to stimulation and friction can be spawned keratinized layer flattened epithelium.

Epithelial cell tumor of the symptoms

Epithelium of malignant tumors collectively referred to as cancer, is the most common type of human malignancy. Cancer in the early general by lymphatic metastasis, to the late occurrence of blood transfer. Occur in the skin, mucosal surface of the appearance of the appearance of often polypoid, the surface often necrosis and ulceration; occurred in the organs often irregular nodular. Anti-cancer experts to introduce you to Epitheliumclassification and symptoms of malignant tumors.