What is the integumentary tissue? Cover tissue: functions, cells and structural features

Fabric - a collection of cells, united by a similar structure and functions, and intercellular substance. From the tissues are formed organs, which, in turn, form systems of organs. Most multicellular organisms consist of many types of tissues.

Diversity

The science that studies tissues (histology) distinguishes many of their types.

Types of animal tissues :

• Connecting;
• Muscular;
• Nervous;
• Integumentary tissue (epithelial);

Types of plant tissues:

• Educational (meristem);
• parenchyma;
• Cover cloth;
• Mechanical;
• Excretory;
• Conducting.

Each type of tissue combines several types.

Types of connective tissue:

• Dense;
• Loose;
• Reticular;
• Cartilaginous;
• Bone;
• Fat;
• lymph;
• blood.

Types of muscle tissue :

• Smooth;
• Cross-striped;
• Heart.

Types of educational tissue :

• Apical;
• Lateral;
• Intercalary.

Species of the conductive tissue :

• xylem;
• phloem.

Types of mechanical fabric:

• Kolenchima;
• Sclerenchyma.

About varieties, structure and functions of the integumentary tissue of animals and plants, we will talk in more detail further.

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 tissue, they are all alike.

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 the cells in space. The latter have an upper and a lower part and are always located upper part closer to the surface of the organ. Another feature that characterizes the structure of the integumentary tissue is that it regenerates well. Her cells do not live 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 inner environment of the body from the outside world.

They also perform metabolic and excretory functions. Often the integumentary tissue is provided with pores to ensure this. The last main function is the receptor function.

One type of integumentary tissue in animals - glandular epithelium - performs a secretory function.

Cover tissues of plants

There are three types:

• Primary;
• Secondary;
• Additional.

To the primary integumentary tissues in plants can include epidermis and exoderm. The first is on the surface of leaves and young stems, and the second - on the root.

Secondary integumentary tissue - periderm. It is covered with more mature stems.

Additional cover cloth is a crust, or rhytid.

Epidermis: structure and function

The main task of this type of tissue is to protect the plant from drying out. It appeared in organisms as soon as they reached the dry land. Algae epidermis is not present yet, but it already exists in spore plants.

The cell of this type of cover cloth has a thickened outer wall. All cells fit tightly to each other.

In higher plants, the whole 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 necessary for water, gas exchange and temperature regulation. The stomatal apparatus is formed by special cells: two closing and several side ones. The closing cells differ from others in an increased amount of chloroplasts. In addition, their walls are unevenly thickened. Another feature of the structure of the closing cells is a greater number of mitochondria and leukoplasts with spare nutrients.

Stem in the higher plants are located on the leaves, most often on their lower side, but if the plant is aquatic on the upper side.

Another feature of the epidermis is the presence of hairs, or trichomes. They can consist of one cell or several. Hairs can be glandular, as, for example, in nettles.

Periderma

This type of integumentary tissue is characteristic of higher plants, which possess a stiffened stalk.

The periderma consists of three layers. Average - Fallogen - is the main one. When dividing its cells, an outer layer is gradually formed - the fallema (cork), and the inner one - the phelloderm.

The main functions of periderm are protection of the plant from mechanical damage, from penetration of pathogens, and also to ensure normal temperature. The latter function is provided by the outer layer - the fellet, since its cells are filled with air.

Functions and structure of the crust

It consists of dead cells of phellogen. The additional cover cloth is located outside, around the periderm.

The main function of the crust is to protect the plant from mechanical damage and from sudden temperature changes.

The cells of this tissue are not able to divide. Cells of other tissues that are inside are divided. Gradually, the crust is stretched, due to which the diameter of the tree trunk increases. However, this tissue has a low enough elasticity, since its cells have very hard cornified membranes. In this regard, soon the crust begins to crack.

Cover cloth in fauna

Types of integumentary tissues of animals are much more diverse than in plants. Let us consider them in more detail.

Depending on the structure, such types of integumentary tissues are distinguished in animals: single-layered epithelium and multilayered. In the shape of cells, the first is subdivided into cubic, flat and cylindrical. Depending on the functions of the tissue and some features of its structure, glandular, sensitive, ciliate 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. By this principle, one can distinguish epidermal, enterodermal, whole-phrenic, ependymoglial and angiodermal types of epithelium. The first is formed from the ectoderm. Most often it is multilayered, but it also happens to be multi-row (pseudo-layered).

Enteroerodermal is formed from the endoderm, it is single-layered. Whole-nephrodermal is formed from the mesoderm. This type of epithelium is single-layer, it can be cubic or flat. Ependymoglial - a special epithelium, which lays the cavity 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 attribute this tissue not to epithelial, but to connective.

Structure and functions

The features of the animal's integumentary tissue consist in the fact that the cells are located very close to each other, the intercellular substance is almost absent.

Another feature is the presence of a basal membrane. It is formed by the activity of the cells of the integumentary and connective tissues. The thickness of the basal membrane is about 1 μm. 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 a link between the cells. The dark plate has a large amount of collagen and other fibrillar structures, which ensure the strength of the membrane. In addition, the dark plate contains fibronectin and laminin, which are necessary for the regeneration of the epithelium.

The multilayered epithelium has a more complex structure than the single-layered epithelium. For example, the epithelium of thick areas of the skin consists of five layers: basal, prickly, granular, shiny and horny. The cells of each layer have different structures. Cells of the basal layer differ in cylindrical shape, spiny layer - in the form of a polygon, granular - rhomboid, shiny - flat, horny - dead scaly cells filled with keratin.

The functions of epithelial tissue are the protection of the body from mechanical and thermal damage, from the penetration of pathogens. Some types of epithelium have specific functions. For example, glandular is responsible for the release of hormones and other substances, such as earwax, sweat, milk and others.

Location of different types of epithelium in the body

For the disclosure of this topic, we present the table.

Type of epithelium	Location
Flat	Oral cavity, nasopharynx, esophagus
Cylindrical	Inner side of stomach, intestine
Cubic	Kanaltsy of the kidneys
Sensitive	The nasal cavity
Ciliated	Airways
Glandular	The glands
Layered	The top layer of the skin (peel, epidermis)

Some of these species have specific functions. For example, the sensory epidermis located in the nose is responsible for one of the five senses - the sense of smell.

conclusions

Cover tissues are characteristic for both plants and animals. In the latter they are much more diverse, have a more complex structure and perform more functions.

Cover tissues of plants are of three types: primary, secondary and additional. Primary characteristic for all plants, except for algae, secondary - for those whose stem is partially rustic, additional - for plants with completely stubby stem.

Cover tissues of animals are called epithelial. There are several of their classifications: the number of layers, the shape of the cells, the functions, the source of formation. According to the first classification, there is a single-layered and multilayer epithelium. The second distinguishes flat, cubic, cylindrical, ciliate. The third one is sensitive, glandular. According to the fourth, there is epidermal, entero-dermal, whole-phrenic, ependymoglial and angiodermal epithelium.

The main purpose of most types of integumentary tissue in animals and plants is to protect the body from any external influences, temperature regulation.