Human tissues are the structures of cells and extracellular living things that have developed historically. Each structure is endowed with certain morphofunctional characteristics inherent only to it. All human tissues interact in the body. This ensures morphofunctional unity in it.
Types of human tissues
There are four types of cell structures. The body has epithelial, nervous, muscle and connective tissue.
The borderline (epithelial) structure includes epithelial cells that line the surface of the body, the mucosa of the cavities and internal organs in the body, and also form glands of both internal and external secretion.
Cells of human epithelial tissue lining the mucosa are located in the basement membrane. The inner surface of this layer is facing directly to the external environment. Epithelial tissue is nourished by diffusion of oxygen and substances through the basement membrane from blood vessels.
Depending on the shape of the cells, a flat (skin), cylindrical (intestine), cubic (renal glomerulus capsule) layer is classified. Depending on the number of layers, single-layer and multi-layer fabric are distinguished. If all the cells in the structure reach the membrane, then this is a single-layer epithelium. In the case when cells are connected to the membrane in only one row, and in the other they are free, then this is a multilayer epithelium. Monolayer epithelial tissue may be mononuclear or multinucleated. It depends on the level at which the cores are located. In some cases, ciliated cilia facing the external environment are present in the structure.
The connective tissue of a person has a very diverse structure. However, all its varieties are formed from mesenchyme (middle germinal leaf). The connective structure should include fibrous, cartilage, lymphatic, hematopoietic tissue and blood. All these varieties belong to the structures of the internal environment.
The blood contains the uniform elements: platelets, white blood cells, red blood cells. In addition, liquid plasma is present in it. In the plasma are hormones, immune bodies, nutritional components. Hematopoietic tissue is located in the bone marrow (red) . In the lymph nodes, intestinal mucosa, liver, spleen, thymus and other organs, the lymphatic structure is located.
Connective tissues of the fibrous structure, in addition to cells, include other elements. They, in particular, contain an intermediate substance, presented in the form of collagen, elastic, argiophilic and reticular fibers, which are enclosed in the main substance.
Connective tissue fibers are present in all tissues and organs. However, they are most pronounced where there is a large mechanical load.
Bone cells are present in the bone structure. They have the ability to form an intermediate substance, which consists of mineral salts, as well as connective tissue fibers.
The cartilaginous structure is divided into hyaline, elastic and fibrous cartilage. Fibrous cartilage contains chondrin with enough collagen fibers to give cartilage strength. In the elastic cartilage layer, chondrin, in addition to collagen, contains elastic fibers and cartilage cells, due to which it has a certain degree of elasticity. The hyaline structure is quite dense, but less durable compared to others.
The human muscle tissue includes the heart muscle, the fibers are smooth and striated. Thanks to this structure, blood vessels and internal organs are contracted, as well as moving parts of the body. The contraction of striated muscles occurs at the will of man. The heart muscle and smooth fibers enter the structure of internal organs. They do not obey human desires.