Tissue is a collection of cells, united by a similar structure and functions, and intercellular substance. Organ tissues form from tissues, which, in turn, form organ systems. Most multicellular organisms are composed of many types of tissue.
Diversity
The science that studies tissues (histology) identifies many of their types.
Types of animal tissue :
- connecting;
- muscle
- Nervous
- integumentary tissue (epithelial);
Types of plant tissue:
- educational (meristem);
- parenchyma;
- integumentary tissue;
- mechanical;
- excretory;
- conductive.
Each type of fabric combines several types.
Varieties of connective tissue:
- dense;
- loose;
- reticular
- cartilaginous;
- bone;
- fatty;
- lymph;
- blood.
Types of muscle tissue :
Types of educational tissue :
- apical;
- lateral;
- insertion.
Varieties of conductive tissue :
Types of mechanical fabric:
We will talk about the varieties, structure and functions of the integumentary tissue of animals and plants in more detail below.
Features of the structure of the integumentary tissue. general information
The structural features 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 a little intercellular substance. Structural particles are located close to each other. The structure of the integumentary tissue also always provides a clear orientation of the cells in space. The latter have an upper and lower part and are always located in 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 do not live long. They are able to quickly divide, due to which the tissue is constantly updated.
The functions of the integumentary tissue
First of all, they play a protective role, separating the internal environment of the body from the outside world.
They also perform metabolic and excretory functions. Often the integumentary tissue is provided with pores to provide this. The last main function is the receptor.
One of the types of integumentary tissue in animals - the glandular epithelium - performs a secretory function.
Plant integumentary tissues
There are three types of them:
- primary;
- secondary;
- additional.
The primary integumentary tissues in plants include the epidermis and exoderm. The first is on the surface of leaves and young stems, and the second is on the root.
Secondary integumentary tissue - periderm. It covers more mature stems.
Additional integumentary tissue - peel, or ritide.
The epidermis: structure and functions
The main task of this type of fabric is to provide the plant with protection against drying out. It appeared in organisms as soon as they went on land. Algae do not yet have an epidermis, but it is already present in spore plants.
A cell of integumentary tissue of this type has a thickened outer wall. All cells fit tightly 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 necessary for water, gas exchange and temperature control. The stomatal apparatus is formed by special cells: two closure and several secondary. Trailing cells are distinguished from others by an increased number of chloroplasts. In addition, their walls are unevenly thickened. Another structural feature of the trailing cells is a greater number of mitochondria and leukoplasts with reserve nutrients.
The stomata of higher plants are located on the leaves, most often on their lower side, but if the plant is water - on the upper.
Another feature of the epidermis is the presence of hairs, or trichomes. They can consist of one cell or several. Hair can be glandular, as, for example, nettle.
Periderm
This type of integumentary tissue is characteristic of higher plants that have a stiffened stalk.
The periderm consists of three layers. The middle one - pellogen - is the main one. When dividing its cells, the outer layer, the fellema (cork), and the inner layer, the felloderm, are gradually formed.
The main functions of the periderm are to protect the plant from mechanical damage, from the penetration of pathogens, as well as ensuring a normal temperature. The last function is provided by the outer layer - Felloma, as its cells are filled with air.
Functions and structure of the peel
It consists of dead pellogen cells. Additional integumentary tissue is located outside, around the periderm.
The main function of the peel is to protect the plant from mechanical damage and from sudden changes in temperature.
Cells of this tissue are not able to divide. Cells of other tissues inside are divided. Gradually, the crust is stretched, due to which the diameter of the tree trunk increases. However, this tissue has a fairly low elasticity, since its cells have very hard keratinized membranes. In this regard, the crust soon begins to crack.
The integumentary tissue of representatives of the fauna
The types of integumentary tissues of animals are much more diverse than those of plants. Let's consider them in more detail.
Depending on the structure, these types of integumentary tissues in animals are distinguished: a single-layer epithelium and a multilayer. According to the shape of cells, the first is divided into cubic, flat and cylindrical. Depending on the functions of the tissue and some features of its structure, a glandular, sensitive, ciliary 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, celonephrodermal, ependymoglial and angiodermal types of epithelium can be distinguished. The first is formed from the ectoderm. Most often it is multilayer, but it also happens to be multilayer (pseudo multilayer).
Enteroderm is formed from the endoderm, it is single-layered. Celonephrodermal is formed from the mesoderm. This type of epithelium is single-layered; it can be cubic or flat. Ependymoglial - a special epithelium that lines the cavity of the brain. It is formed from the neural tube of the embryo, is a single layer, flat. Angioderm is formed from mesenchyme, it is located on the inner side of the vessels. Some researchers attribute this tissue not to the epithelial, but to the connective.
Structure and function
Features of the integumentary tissue of animals are that the cells are located very 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 the cells of the integumentary and connective tissues. The thickness of the basement membrane is about 1 Ξm. 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 that provide membrane strength. In addition, the dark plate contains fibronectin and laminin, which are necessary for the regeneration of the epithelium.
The 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, prickly, granular, shiny and horny. The cells of each layer have a different structure. The cells of the basal layer are cylindrical, the spiky layer is in the form of a polygon, granular - diamond-shaped, shiny - flat, horny - dead scaly cells filled with keratin.
The functions of epithelial tissue is 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 is responsible for the release of hormones and other substances such as earwax, sweat, milk and others.
The location of different types of epithelium in the body
To expand on this topic, we present a table.
| Type of epithelium | Location |
| Flat | Oral cavity, nasopharynx, esophagus |
| Cylindrical | The inner side of the stomach, intestines |
| Cubic | Renal tubules |
| Sensitive | Nasal cavity |
| Ciliated | Airways |
| Glandular | Glands |
| Layered | Top layer of 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
The 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.
The integumentary tissues of plants are of three types: primary, secondary and additional. Primary are characteristic of all plants, except algae, secondary - for those whose stalk partially stiffens, additional - for plants with a completely woody stalk.
The integumentary tissues of animals are called epithelial. There are several classifications: by the number of layers, by the shape of cells, by function, by source of formation. According to the first classification, there is a single-layer and multi-layer epithelium. The second distinguishes flat, cubic, cylindrical, ciliary. The third is sensitive, glandular. According to the fourth, there is epidermal, enterodermal, celonephrodermal, ependymoglial and angiodermal epithelium.
The main purpose of most types of integumentary tissue in animals and plants is to protect the body from any environmental influences, and regulate temperature.