Even school children are taught anatomy course a simple biological patterns in the structure of living multicellular beings, the basis of all - a cell.Group gives rise to their tissues, which in turn form organs.The last combined in the system, performing vital functions, metabolic processes, and so on.
So what tissues, their structure and function, is studied from the secondary level curriculum.Consider what types of tissue found in the composition of the human body, what the epithelial variety of data structures and what is its value.
animal tissue: classification
fabrics, their structure and function, especially the development and operation are of great importance in the life of all living beings, who are capable of their formation.They perform a protective function, secretory, organoobrazovatelnuyu, nutritional, thermal insulation, and many others.Total
can distinguish 4 types of tissue, specific to the structure of the body of man and higher animals.
- Different types of epithelial tissue or cover (leather).
- Connective tissue presented a few basic varieties: bone, blood, fat and others.
- nervous, formed a kind of branched cells.
- muscle tissue forming the skeleton with the musculoskeletal system of the whole organism.
Each of these has its place tissue localization, the process of education and performs certain functions.
General characteristics of epithelial tissue
If characterize types of epithelial tissues in general, you should allocate some key features that they all have, each to a greater or lesser extent.For example:
- no material between the cells, which makes the structure of tightly adjacent to each other;
- unique way power lies not in the absorption of oxygen from the blood vessels, and diffusion through the basement membrane of connective tissue;
- unique ability to recover, that is, regeneration structure;
- the tissue cells are called epithelial cells;
- each epithelial cell has a polar ends, so all the tissue as a result has polarity;
- under any type of epithelium is the basement membrane, which is important;
- localization of the tissue is carried in the body layers or strands at specific locations.
Thus, it turns out that the variety of epithelial tissue are united by common laws in the arrangement and structure of the organization.
Types of epithelial tissue
They can be divided into three main.
- surface epithelial tissue.The epithelium of its structure is particularly tight, because it performs primarily defensive function.It forms a barrier between the outside world and the inside of the body (skin, integument bodies).In turn, this type includes several components, which are discussed further.
- glandular epithelial tissue.The glands, ducts that open to the outside, that is exogenous.To those include tear, sweat, milky, greasy floors.
- Secretory variety of epithelial tissue.Some scientists believe that part of the nerve cells eventually turns into epithelial cells and produces this type of structure.The main function of the epithelium - perceive the stimulus, both mechanical and chemical, transmitting the signal of this organism in appropriate instances.
These are the main types of epithelial tissue, which are allocated as part of the human body.Now consider the detailed classification of each.
Classification of epithelial tissues
It is quite capacious and complex as a multi-faceted structure of each of the epithelium, and the functions performed are very different and specific.In general, all existing versions of the epithelium into the following system.The entire surface epithelium is divided so.
1. A single layer.Cells were arranged in one layer and in direct contact with the basement membrane, in contact with it.Its such a hierarchy.
A) Single row are divided into:
Each of these types can be limbic and beskaemchatym.
B) Pseudostratified including:
- ciliated columnar (ciliated);
- prismatic bezresnitchaty.
2. The multilayer.The cells are arranged in several rows, so the contact with the basement membrane is carried out only in the deepest layer.
B) Stratum flat.
B) neorogovevayuschy divided into:
glandular epithelium also has its own classification.It is divided into:
- multicellular epithelium.
Moreover, these endocrine glands may be leading out the secret of the blood and exocrine having duct epithelium under consideration.
sensory tissue division in the structural units are not allowed.It consists of forming it transformed into epithelial cells of the nerve cells.
Simple squamous epithelium
got its name for the structure of the cells.Its epithelial cells are thin and flattened structure which tightly interconnected.The main objective of this epithelium - provide good permeability to molecules.Therefore, the basic localization:
- alveoli of the lungs;
- walls of blood vessels and capillaries;
- lines the inside of the abdominal cavity;
- covering serous membranes;
- generates some ducts of the kidneys and the renal corpuscles.
epithelial cells themselves have the mesothelial or endothelial origin and characterized by the presence of a large oval nucleus in the center of the cell.
These types of epithelial tissue as single and multi cubic epithelium, have several structural features of the cell in shape.For what, in fact, got its name.They are the cubes slightly irregular shape.
single layer cubic localized in renal tubule function and performs it permeable membrane.Nuclei in these cells are rounded, are shifted to the cell wall.
multilayer cuboidal epithelium arranged in a number of deep layer in contact with the basement membrane.All other exterior structures cover it from above in the form of flat flakes of epithelial cells.This type of tissue forms a plurality of:
- mouth and others.
Prismatic epithelium is a single layer
This is one type of tissue, also called epithelium.Features of the structure, functions are explained in cell shape: cylindrical, elongated.Main localization:
- thin and rectum;
- some renal tubule.
main function - increase the suction surface of the working body.In addition, here ducts open specialized goblet cells secrete mucus.
Types of epithelial tissues: single-layer multi-row
This kind of surface epithelium.Its main task - is to ensure the integument of the respiratory tract, which they lined.All cells in close contact with the basement membrane of the nucleus in their circular, at differing levels.
ciliated epithelium called this because the edges are framed epithelial cilia.In total, you can select 4 species belonging to the structure of the cell:
- long intercalary;
- goblet slime.
addition, simple pseudostratified epithelium found in genital ducts and corresponding system (oviducts, testicles, etc.).
Stratified transitional epithelium
The most important feature of any stratified epithelium that its stem cells can be, that is, those which are capable of differentiating into any other kinds of tissue.Specifically
transitional epithelial cells are part of the bladder and associated ducts.They are divided into three large groups, united by a common ability - to form tissues with high elongation.
- Basal - small cells with nuclei round shape.
- surface - a very large cell size, usually in the form of the dome.
contact with the membrane in these tissues is not, so the power of the diffuse located underneath the loose connective tissue structure.Another name for this type of epithelium - urothelium.
neorogovevayuschy Stratified epithelium
refer to this type of epithelial tissue of the body that line the inner surface of the cornea, the structure of the mouth and esophagus.All epithelial cells can be divided into three types:
- flat cells.
The organs they form bands of flat structure.Neorogovevayuschy Named for its ability to exfoliate over time, that is removed from the surface of the body, being replaced by younger counterparts.
Multilayer keratinizing epithelium
Its definition can be as follows: it is the epithelium, the upper layers which are capable of forming solid peredifferentsirovke and scales - the cornea.Among all the surface epithelium - the only one which is characterized by such a feature.His one can see with the naked eye, because the main body of this layer - the skin.It composed of epithelial cells of different structures, which can be grouped into several basic layers:
Last - the most dense and thick, presented horny scales.It is their desquamation we see when your skin starts to peel off under the influence of adverse environmental conditions or old age.Basic protein molecules of the fabric - keratin and filaggrin.
addition to the cover, is of great importance and glandular epithelium.It is another form that is epithelial tissue.Considered tissue and their classification is very important for a proper understanding of their place of localization and functions in the body.
So, glandular epithelium is very different from the cover and all its varieties.Its cells are called glandulotsitami, they are an integral part of various glands.In total there are two main types:
- exogenous cancer;
Those who throw their secrets directly into the glandular epithelium, and not blood, belong to the second group.These are: salivary, dairy, greasy, sweat, tear, sex.
Also, there are several options secretion, ie, elimination of substances out.
- eccrine - cells release compounds, but do not lose the integrity of the structure.
- apocrine - secretion after removing partially destroyed.
- holocrine - cells are destroyed completely after the function.
iron work - a very important and significant.For example, their function is - protective, secretory signal and so on.
basement membrane: function
All types of epithelial tissues are closely in contact with at least one layer of its structure such as the basement membrane.Its structure consists of two bands - light, consisting of calcium ions, and the dark - including various fibrous compounds.
she co-production of connective tissue and epithelium.Functions of the basement membrane of the following:
- manual (hold epithelial together, while maintaining the integrity of the structure);
- barrier - selective permeability to substances;
- trophic - power implementation;
- morphogenetic - providing a high capacity for regeneration.
Thus, the combined interaction of epithelial tissue and basement membrane resulting in a smooth and orderly operation of the body, the integrity of its structures.
In general, very important not only epithelial tissue.Fabrics and their classification is considered at all levels of training related to medicine and anatomy, which proves the importance of these topics.