Tissue is a collection of cells united by a similar structure and functions, and intercellular substance. Tissues form organs, which in turn form organ systems. Most multicellular organisms are made up of many types of tissues.
Variety
The science that studies tissues (histology) distinguishes many types of tissues.
Animal tissue types:
- connective;
- muscular;
- nervous;
- integumentary tissue (epithelial);
Types of plant tissues:
- educational (meristem);
- parenchyma;
- cover fabric;
- mechanical;
- excretory;
- conductive.
Each type of fabric combines several types.
Types of connective tissue:
- dense;
- loose;
- reticular;
- cartilaginous;
- bone;
- fatty;
- lymph;
- blood.
Types of musclefabrics:
- smooth;
- striped;
- hearty.
Types of educational fabric:
- apical;
- side;
- insert.
Varieties of conductive fabric:
- xylem;
- phloem.
Types of mechanical fabric:
- colenchyma;
- sclerenchyma.
We will talk about the varieties, structure and functions of the integumentary tissue of animals and plants in more detail later.
Features of the structure of the integumentary tissue. General information
The peculiarities of the structure of the integumentary tissue are determined by its purpose. Although there are many varieties of this type of fabric, they are all similar.
It always has a large number of cells and little intercellular substance. Structural particles are located close to each other. The structure of the integumentary tissue also always provides for a clear orientation of cells in space. The latter have an upper and lower part and are always located with the upper part closer to the surface of the organ. Another feature that characterizes the structure of the integumentary tissue is that it is well regenerated. Her cells don't last long. They are able to quickly divide, due to which the fabric is constantly updated.
Functions of integumentary tissues
First of all, they play a protective role, separating the body's internal environment from the outside world.
They also perform metabolic and excretory functions. Often the integumentary tissue is provided with pores to ensure this. Lastthe main function is receptor.
One of the types of integumentary tissue in animals - the glandular epithelium - performs a secretory function.
Integumentary tissues of plants
There are three types:
- primary;
- secondary;
- extra.
Epidermis and exoderm can be attributed to the primary integumentary tissues in plants. The first is on the surface of the leaves and young stems, and the second is on the root.
Secondary integumentary tissue - periderm. More mature stems are covered with it.
Additional integumentary tissue - crust, or ritidome.
Epidermis: structure and functions
The main task of this type of fabric is to protect the plant from drying out. It appeared in organisms as soon as they came to land. Algae do not yet have an epidermis, but spore plants already have it.
This type of integumentary tissue cell has a thickened outer wall. All cells fit snugly together.
In higher plants, the entire surface of the tissue is covered with a cuticle - a layer of cutin wax.
The structure of the integumentary tissue of plants provides for the presence of special pores - stomata. They are essential for water and gas exchange and temperature regulation. The stomatal apparatus is formed by special cells: two trailing and several secondary. Guard cells differ from others in the increased number of chloroplasts. In addition, their walls are unevenly thickened. Another structural feature of guard cells is a greater number of mitochondria andleucoplasts with reserve nutrients.
Stomata in higher plants are located on the leaves, most often on their lower side, but if the plant is aquatic - on the top.
Another feature of the epidermis is the presence of hairs, or trichomes. They may consist of one cell or several. The hairs can be glandular, like nettles.
Periderm
This type of integumentary tissue is characteristic of higher plants that have a stiff stem.
Periderm consists of three layers. The middle one - phellogen - is the main one. With the division of its cells, the outer layer is gradually formed - phellem (cork), and the inner - phelloderm.
The main functions of the periderm are to protect the plant from mechanical damage, from the penetration of pathogens, as well as to ensure normal temperature. The last function is provided by the outer layer - phellem, since its cells are filled with air.
Functions and structure of the crust
It consists of dead phellogen cells. Additional integumentary tissue is outside, around the periderm.
The main function of the peel is to protect the plant from mechanical damage and sudden changes in temperature.
The cells of this tissue are unable to divide. The cells of other tissues inside are dividing. Gradually, the crust is stretched, due to which the diameter of the tree trunk increases. However, this tissue has a rather low elasticity, since its cells have very hard keratinizedshells. In this regard, the crust soon begins to crack.
Integumentary tissue of fauna
Types of integumentary tissues of animals are much more diverse than those of plants. Let's take a closer look at them.
Depending on the structure, these types of integumentary tissues in animals are distinguished: single-layer epithelium and multilayer. According to the shape of the cells, the first is divided into cubic, flat and cylindrical. Depending on the functions of the tissue and some features of its structure, glandular, sensitive, ciliated epithelium is distinguished.
There is another classification of the epidermis - depending on the tissue from which it is formed during the development of the embryo. According to this principle, epidermal, enterodermal, whole nephrodermal, ependymoglial and angiodermal types of epithelium can be distinguished. The first is formed from the ectoderm. Most often it is multi-layered, but it can also be multi-rowed (pseudo-multilayered).
Enterodermal is formed from the endoderm, it is single-layered. The coelonephrodermal is formed from the mesoderm. This type of epithelium is single-layer, it can be cubic or flat. Ependymoglial is a special epithelium that lines the cavities of the brain. It is formed from the neural tube of the embryo, is single-layer, flat. Angiodermal is formed from the mesenchyme, it is located on the inside of the vessels. Some researchers refer to this tissue not as epithelial, but as connective.
Structure and functions
Features of the integumentary tissue of animals are that the cells are locatedvery close to each other, the intercellular substance is almost absent.
Another feature is the presence of a basement membrane. It is formed due to the activity of cells of the integumentary and connective tissues. The basement membrane is about 1 µm thick. It consists of two plates: light and dark. The first is an amorphous substance with a low protein content, rich in calcium ions, which provide communication between cells. The dark lamina has a large amount of collagen and other fibrillar structures that provide strength to the membrane. In addition, the dark plate contains fibronectin and laminin, which are necessary for the regeneration of the epithelium.
Multilayer epithelium has a more complex structure than a single layer. For example, the epithelium of thick areas of the skin consists of five layers: basal, spiny, granular, shiny and horny. The cells of each layer have a different structure. The cells of the basal layer are cylindrical in shape, the prickly layer is polygonal, the granular layer is diamond-shaped, the shiny layer is flat, the horny layer is dead scaly cells filled with keratin.
The functions of epithelial tissue are to protect the body from mechanical and thermal damage, from the penetration of pathogens. Some types of epithelium have specific functions. For example, the glandular gland is responsible for the secretion of hormones and other substances such as earwax, sweat, milk, and others.
Location of different types of epithelium in the body
To reveal thistopics present table.
| Epithelial type | Location |
| Flat | Oral cavity, nasopharynx, esophagus |
| Cylindrical | Inner side of the stomach, intestines |
| Cubic | Kidney tubules |
| Sensitive | Nasal cavity |
| Ciliated | Airways |
| Glandular | Glands |
| Multilayer | Top layer of skin (skin, epidermis) |
Some of these species have specific functions. For example, the sensory epidermis in the nose is responsible for one of the five senses, smell.
Conclusions
Integumentary tissues are characteristic of both plants and animals. In the latter, they are much more diverse, have a more complex structure and perform more functions.
Integumentary tissues of plants are of three types: primary, secondary and additional. Primary are characteristic of all plants, except for algae, secondary - for those whose stem is partially lignified, additional - for plants with a completely lignified stem.
Integumentary tissues of animals are called epithelial. There are several classifications of them: by the number of layers, by the shape of cells, by functions, by the source of formation. According to the first classification, there is a single-layer and stratified epithelium. The second highlights flat, cubic, cylindrical, ciliated. Third -sensitive, glandular. Fourth, there are epidermal, enterodermal, coelonephroderm, ependymoglial, and angiodermal epithelium.
The main purpose of most types of integumentary tissue in both animals and plants is to protect the body from any environmental influences, temperature regulation.
