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 are made up of many types of fabrics.
Diversity
The science that studies tissue (histology) distinguishes many types.
- connecting;
- muscular;
- nervous;
- cover tissue(epithelial);
Types of plant tissues:
- educational (meristem);
- parenchyma;
- mechanical;
- excretory;
- conductive.
Each type of fabric combines several types.
Types of connective tissue:
- dense;
- loose;
- reticular;
- cartilaginous;
- bone;
- fat;
- lymph;
- blood.
- smooth;
- striated;
- cardiac.
- apical;
- lateral;
- intercalary
- xylem;
- phloem.
Types of mechanical fabric:
- colenchyma;
- sclerenchyma.
We will talk about the types, structure and functions of the integumentary tissue of animals and plants in more detail below.
Features of the structure of 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 contains 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 bottom part and are always located top part closer to the surface of the organ. Another feature that characterizes the structure of the integumentary tissue is that it regenerates well. Its cells do not live long. They are able to quickly divide, due to which the tissue is constantly renewed.
Functions of integumentary tissues
First of all, they play a protective role, separating internal environment body from the outside world.
They also perform metabolic and excretory functions. Often the covering tissue is provided with pores to ensure this. The last main function is receptor.
One of the types of integumentary tissue in animals - glandular epithelium - performs secretory function.
Plant integumentary tissues
There are three types:
- primary;
- secondary;
- additional.
The primary integumentary tissues in plants include the epidermis and exoderm. The first is located on the surface of leaves and young stems, and the second is on the root.
The secondary integumentary tissue is the periderm. More mature stems are covered with it.
Additional covering tissue is a crust, or rhytide.
Epidermis: structure and functions
The main task of this type of fabric is to provide the plant with protection from drying out. It appeared in organisms as soon as they reached land. Algae do not yet have an epidermis, but spore-bearing plants already have one.
This type of integumentary tissue cell has a thickened outer wall. All cells are tightly adjacent to each other.
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 and gas exchange and temperature regulation. The stomatal apparatus is formed by special cells: two guard cells and several subsidiary cells. Guard cells differ from others in having an increased number of chloroplasts. In addition, their walls are unevenly thickened. Another structural feature of guard cells is a larger number of mitochondria and leukoplasts 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 upper.
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, as, for example, in nettles.
Periderm
This type of integumentary tissue is characteristic of higher plants that have woody stems.
The periderm consists of three layers. The middle one - phellogen - is the main one. As its cells divide, it gradually forms outer layer- phellem (cork), and internal - phelloderm.
The main functions of the periderm are to protect the plant from mechanical damage, from the penetration of pathogenic organisms, and also to provide normal temperature. The latter function is provided by the outer layer - the phellem, since its cells are filled with air.
Functions and structure of the crust
It consists of dead phellogen 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 sharp changes temperature.
The cells of this tissue are not able to divide. The cells of other tissues inside divide. Gradually, the crust stretches, due to which the diameter of the tree trunk increases. However this fabric has rather low elasticity, since its cells have very hard keratinized membranes. As a result, the crust soon begins to crack.
Integumentary tissue in representatives of fauna
The 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, the following types of integumentary tissues in animals are distinguished: single-layer epithelium and multilayer epithelium. 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, and ciliated epithelium are 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, coelonephrodermal, 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-row (pseudo-layered).
Enterodermal is formed from the endoderm; it is single-layered. Coelonephrodermal is formed from mesoderm. This type of epithelium is single-layered; 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 and is single-layered and flat. Angiodermal is formed from mesenchyme, it is located on inside vessels. Some researchers classify this tissue not as epithelial, but as connective.
Structure and functions
The peculiarities 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 cells of the integumentary and connective tissues. The thickness of the basement membrane is about 1 micron. 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 plate has a large amount of collagen and other fibrillar structures that provide the strength of the membrane. In addition, the dark plate contains fibronectin and laminin, which are necessary for epithelial regeneration.
Multilayer epithelium has a more complex structure than single-layer epithelium. For example, the epithelium of thick skin consists of five layers: basal, spinous, granular, shiny and horny. The cells of each layer have a different structure. The cells of the basal layer are cylindrical in shape, the spinous layer is in the shape of a polygon, the granular layer is diamond-shaped, the shiny layer is flat, and 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 and from the penetration of pathogens. Some types of epithelium have specific functions. For example, the glandular 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 cover this topic, we present a table.
Some of these species have specific functions. For example, the sensory epidermis located in the nose is responsible for one of the five senses - smell.
conclusions
Integumentary tissues are characteristic of both plants and animals. For the latter, they are much more diverse, have a more complex structure and perform more functions.
There are three types of integumentary tissues of plants: primary, secondary and accessory. Primary are characteristic of all plants except algae, secondary - for those whose stems are partially woody, additional - for plants with a completely woody stem.
The integumentary tissues of animals are called epithelial. There are several classifications: by the number of layers, by the shape of cells, by functions, by the source of formation. According to the first classification, there is single-layer and multilayer epithelium. The second distinguishes flat, cubic, cylindrical, ciliated. The third is sensitive, glandular. According to the fourth, there are epidermal, enterodermal, coelonephrodermal, 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 influences. external environment, temperature regulation.
Let's look at the structure plant cell under a microscope.
Oblong cells are visible, tightly adjacent to one another. Each cell has a dense transparent shell, in which in some places there are thinner sections - pores. Under the shell there is a living, colorless, viscous substance - cytoplasm. The cytoplasm moves slowly. The movement of the cytoplasm promotes the movement of nutrients and air within the cells. When strongly heated and frozen, the cytoplasm is destroyed, and then the cell dies. In the cytoplasm there is a small dense body - core, in which one can distinguish nucleolus. By using electron microscope it was found that the nucleus has a very complex structure.
In almost all cells, especially in old ones, cavities are clearly visible - vacuoles (from the Latin word "vacuum" - empty). They're filled cell sap. Cell sap is water with sugars and other organic and inorganic substances dissolved in it.
In the cytoplasm of a plant cell there are numerous small bodies - plastids. At high magnification, the plastids are clearly visible. In cells different organs The number of plants varies. The color of certain parts of plants depends on the color of the plastids and the coloring substances contained in the cell sap. Green plastids are called chloroplasts.
All plant organs are made up of cells. Therefore, the plant has cellular structure
, and each cell is a microscopic component of the plant. The cells are adjacent to one another and connected by a special intercellular substance, which is located between the membranes of neighboring cells. If all the intercellular substance is destroyed, the cells are separated.
Often, living growing cells of all plant organs become somewhat rounded. At the same time, their shells move away from each other in places; in these areas the intercellular substance is destroyed. arise intercellular spaces filled with air. The network of intercellular spaces is connected to the air surrounding the plant through special intercellular spaces located on the surface of the organs.
Each living cell breathes, eats and grows over a period of time. Substances necessary for nutrition, respiration and growth of the cell enter it from other cells and from intercellular spaces, and the entire plant receives them from the air and soil. Almost all substances necessary for cell life pass through the cell membrane in the form of solutions.
CELL DIVISION
Cell division is preceded by division of its nucleus. Before cell division, the nucleus enlarges and usually cylindrical bodies - chromosomes (from Greek words"chromo" - color, "soma" - body). They transmit hereditary traits from cell to cell. 
Before division, the number of chromosomes doubles. All living contents of the cell are also evenly distributed between new cells. So, cell division begins with division of the nucleus and each of the resulting cells contains the same number of chromosomes as the nucleus of the original cell.
Young cells, unlike old ones that are unable to divide, contain many small vacuoles. The nucleus of a young cell is located in the center. An old cell usually has one large vasole, and the cytoplasm, in which 
The nucleus is located adjacent to the cell membrane. Young, newly formed cells enlarge and divide again. So, as a result of cell division and growth, all plant organs grow.
TISSUE CELLS
A group of cells that have a similar structure and perform the same functions is called cloth. Plant organs are composed of different tissues.
A tissue whose cells are constantly dividing is called educational.
Integumentary fabrics protect plants from adverse environmental influences.
Responsible for transporting substances to all plant organs conductive textile.
In cells storing fabrics are put into storage nutrients.
Photosynthesis occurs in the green cells of the tissue of leaves and young stems. Such fabrics are called photosynthetic.
Mechanical tissue gives strength to plant organs.
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IN multicellular organism groups of cells are adapted to perform
certain functions. Such groups of cells having the same structure and their intercellular substance, performing the same functions, form tissues.
Intercellular substance fills the spaces between cells. It is a product of cell activity.
In humans, as in animals, there are four types of tissues: epithelial, connective, muscle and nervous.
Epithelial tissue. Epithelial tissues form the surface layers of the skin, mucous membranes internal organs(digestive tract, respiratory and urinary tract), form numerous glands, lining the inside of blood vessels.
The epithelium of the skin and cornea of the eyes protects against adverse external influences, and the epithelium of the stomach and intestines protects their walls from the action of digestive juices. Nutrients are absorbed into the blood through the intestinal epithelium, and gas exchange occurs in the lungs through epithelial cells.
Ferrous epithelial cells secrete various substances (secrets). Glandular epithelium forms glands. There are glands of external and internal secretion.
In the former, the secretion is released through special ducts onto the surface of the body or into the body cavity (such as the sweat, salivary, mammary glands). The endocrine glands do not have ducts, and their secretion (hormone) is released directly into the blood.
Despite the variety of functions, epithelial tissue have a number characteristic features. Their cells are tightly adjacent to each other, arranged in one or several rows, the intercellular substance is poorly developed. When damaged, epithelial tissue cells are quickly replaced by new ones.
Connective tissues. In the human body, there are several types of connective tissue, which at first glance are very different: cartilage, bone, fat, blood. Their structure and functions are different, but they all have a well-developed intercellular substance. The intercellular substance may vary depending on the function performed by the tissue. So, in blood it is liquid, in bones it is solid, in cartilage it is elastic, elastic.
Connective tissues perform various functions. Fibrous connective tissue fills the gaps between organs, surrounds blood vessels, nerves, muscle bundles, forms the inner layers of the skin - the dermis and fatty tissue. The supporting, mechanical function is performed by bone and cartilage tissue. Blood performs nutritional, transport and protective functions.
Muscle tissue. This is a group of tissues that have different structures and origins, but are united common feature the ability to contract, change its length, shorten. Smooth muscle tissue is found in the walls of internal organs, blood vessels and lymphatic vessels, gland ducts. It is formed by small-sized (up to 100-120 µm) spindle-shaped mononuclear muscle cells. The contraction of smooth muscles occurs automatically, that is, against our will. Smooth muscles can remain in a contracted state for a long time.
Cross-striped muscle tissue forms skeletal muscles attached to the bones of the skeleton. Its important property is the ability to contract, subject to the conscious effort of a person. The main element of the tissue is the muscle multinuclear fiber; it has a significant length - from 1 to 45 mm, and in some muscles even up to 12 cm. The tissue received its name because the transverse striation of its fibers is visible under a microscope. Striated fibers differ from smooth muscle cells not only in structure, but also in that they can contract and relax much faster.
Cardiac muscle tissue is formed by cells adjacent to each other with cross-striations. These are elongated, up to 150 microns, cells with one, less often two, nuclei. Thanks to the complex interweavings that these cells form, not individual bundles of the heart contract, but the entire cardiac muscle at once: first at the atria, then at the ventricles.
Nervous tissue. Forms organs nervous system. It distinguishes between the main nerve cells- neurons and auxiliary - neuroglial cells.
Neurons are able to perceive stimuli, become excited, and produce and transmit nerve impulses. They are also involved in processing, storing and retrieving information from memory. Each cell has a body, processes and nerve endings. The processes vary in structure, shape and function.
Short branched processes (dendrites) perceive and transmit excitation to the body of the neuron, and along a single long process (axon) the excitation is transmitted to another neuron or to the working organ. The length of some nerve fibers (processes) can reach 1 m or more.
Neuroglia performs supporting, protective and nutritional functions.
In nervous tissue, neurons, in contact with each other, form chains. The places where neuron processes contact each other are called synapses. Excitation is transmitted through neurons in the form of a nerve impulse.
Organs. Tissues form organs. An organ is a part of the body that has a certain shape and structure, occupies a certain place in the body and performs a certain function. Usually all types of tissues take part in the formation of an organ, but one of them is always the main, “working” one. For example, for the brain the main tissue is nervous tissue, for the skin - epithelial tissue, for muscles - muscle tissue. All other tissues perform auxiliary functions.
Heart, kidneys, stomach, eyes, lungs - all these are organs of our body.
The vital activity of the body is ensured by work and interaction various organs, which make up organ systems.
Test your knowledge
- What is fabric?
- What are the types of fabrics?
- What is epithelial tissue made of?
- What features are characteristic of epithelial tissue?
- Name the types of connective tissue.
- What is intercellular substance?
- What features are characteristic of smooth muscle tissue?
- What structural features distinguish striated muscle tissue from the heart?
- What is a neuron?
Think
Why liquid blood classified as fabrics?
Tissue is a group of cells that are similar in structure and origin, perform a specific function and are interconnected by an intercellular substance. Tissues form organs. An organ is a part of the body that occupies a specific place in the body, has a specific shape and structure, and performs a specific function.
The most important part of the leaf is the leaf blade. The outside of the leaf blade is covered with skin (epidermis). There are no chloroplasts in the skin cells, so it easily transmits light to the main tissues of the leaf. The skin cells adhere tightly to each other and reliably protect the internal tissues of the leaf.
The top of the skin may be covered with a layer of wax or waxy substance, which also carries protective function. They prevent the penetration of pathogenic microorganisms into the leaves, protect the leaf from overheating and excessive evaporation of water. The same role is played by hairs, which are outgrowths of skin cells and sometimes densely cover the leaf. For leaves located horizontally, the skin of the upper and lower sides is slightly different in structure. Among the cells of the integumentary tissue on the underside of the leaf blade are located stomata.
There must be atttttttttttttt
Stoma
- slit hole in the skin (epidermis), surrounded by two guard cells. Serves for gas exchange and transpiration. In the light, with sufficient moisture, the stomata are open, in the dark or with a lack of water, they are closed.
Rice. A-closed, B-open. 1 - guard cells of the stomata, 2 - stomatal slit, 3 - chloroplasts, 4 - adjacent cells of the leaf skin (main epidermis), 5 - thickened cell wall, 6 - thin cell wall.
Mechanism of operation stomata are due to the following structural features of the guard cells: they contain chloroplasts, while the remaining cells of the epidermis do not contain them; guard cells have a thickened wall on the side of the stomatal fissure. In the light, the process of photosynthesis occurs only in the guard cells; the resulting sugars increase the concentration of cell sap, which, due to the laws of osmosis, causes the flow of water into these cells. Turgor pressure increases, and the cells begin to swell, increasing in volume. But this is prevented by the cell wall, especially its thick side facing the stomatal fissure. As a result, the guard cells stretch towards the main epidermis, where the walls are thinner and the thick ones follow the entire cell - the stomata opens. At night, when photosynthesis does not occur, the guard cells return to their place and close - the stomata closes. It was noted that when stomata open, potassium ions move into the guard cells, which also determine an increase in turgor pressure and cell volume
Evaporation in hot weather helps cool the leaves, move water and substances dissolved in it throughout the plant, but if the soil is not sufficiently moistened, it leads to wilting or even death of the plant. There is evaporation of water through the cuticle on the surface of the plant ( cuticular) And stomatal(through stomata).
Under the skin there is chlorophyll-bearing parenchyma ( chlorenchyma ). This tissue forms the pulp of the leaf. This is where the process of photosynthesis occurs. Under upper epidermis located columnar chlorenchyma(textile). Its cells are elongated, tightly adjacent to each other, and contain many chloroplasts. Typically, chloroplasts are oriented in such a way as to maximize the energy of sunlight. The layer of columnar tissue is optimally illuminated, and the process of photosynthesis occurs intensively in it.
Plants grown in bright light conditions usually have two or three layers of columnar tissue called leaves.
In plants grown in the shade, with a lack of light, columnar cells form only one thin layer in the upper part of the leaf - they are called shadow cells.
Under the columnar chlorenchyma (tissue) is spongy chlorenchyma(tissue), the cells of which are round or oblong, contain fewer chloroplasts and are loosely located, since large intercellular spaces filled with air develop between the cells. Spongy tissue is adjacent to the lower epidermis. The process of photosynthesis in spongy tissue is not as intense as in columnar tissue, but the processes of transpiration and gas exchange are active here. The air passes through the stomata, enters the intercellular spaces and travels through them to all leaf tissues. Water in a gaseous state, oxygen and carbon dioxide, formed during photosynthesis and respiration, are collected in the intercellular spaces, and from them are released through the stomata. Thus, both types of assimilative tissue are interconnected into a single complex system.
In the center of the leaf there is a large conductive bundle, and on the side there are smaller bunches. In the upper part of the conducting bundle there are sieve tubes and companion cells. Adjacent to them below are elements of water-conducting fabric - vessels And tracheids. The conducting bundle of the sheet also contains mechanical fabric, which is located either in the form of a closed ring, or in separate sections at the top and bottom. The mechanical fabric strengthens the conductive bundles and gives the sheet mechanical strength.
On the surface of the sheet, conducting bundles clearly appear in the form veins.
The nature of the arrangement of veins in a leaf (venation) is an important systematic feature.
Leaf venation is:
ü arc(lily of the valley leaf);
ü parallel(cereal leaf).
Arc and parallel venation are characteristic of monocotyledonous plants.
Dicotyledonous plants are characterized by reticulate venation:
ü palmate, when all the veins converge at one point at the base of the leaf blade (Tatar maple);
ü feathery, when the central vein is pronounced (leaf of bird cherry, birch).
| Leaf fabric | Structure | Function |
| cover tissue | The upper skin is formed by tightly pressed transparent cells (4) of irregular shape. Often covered cuticle or hairs | Facing the sun, protection from external influences and evaporation |
| The lower skin usually has stomata. The stomata are formed by two guard cells (2), the walls of which are thickened on one side, with a stomatal fissure (1) located between them. Guard cells have chloroplasts (3). | Located on the underside of the sheet. Protection, breathing and evaporation | |
| Main fabric: columnar | Tightly lying cylindrical cells with chloroplasts | Located on the upper side of the sheet. Serves for photosynthesis |
| spongy | Round cells with intercellular spaces forming air cavities contain less chlorophyll | Located closer to the underside of the leaf. Photosynthesis + water and gas exchange |
| Mechanical | Leaf vein (fiber) | Elasticity and strength |
| Conductive | Leaf vein: - vessels | Flow of water and minerals from the root |
| - sieve tubes | Water flow and organic matter to the stem and root |
Ø C2. What type of leaf is shown in the picture? Which parts of the sheet are indicated in the figure by numbers 1 and 2 and what functions do they perform? 1) a simple leaf with reticulate veins and stipules; 2) 1-leaf blade, performs the functions of photosynthesis, gas exchange, transpiration, and in some plants - vegetative propagation; 3) 2 - veins provide transport of substances and support of the leaf.
Groups of cells have different purposes: some serve as support for the body, others provide nutrition, and others transport substances in the body. They have their own names according to the “work” they do.
Fabrics
A tissue is a group of cells that have a common origin. similar structure and performing a specific function in a living organism.
In some tissues, cells are located very close to each other, in others there are gaps between them - intercellular spaces (intercellular spaces).
Plant integumentary tissues
Integumentary tissues are located on the surface of all plant organs. They protect plants from adverse external influences: drying out, mechanical damage, penetration of pathogenic microorganisms into internal tissues.
Let us consider the structure of integumentary tissue using the example of leaf skin. The skin cells are alive. Most of them are large, tightly adjacent to each other, and transparent. Transparency allows sunlight penetrate into the leaf. Other skin cells are smaller and green, as they contain chloroplasts. These cells are arranged in pairs and are called guard cells. If they move away from each other, a gap appears between them; if they move closer (closed), the gap disappears. The gap that appears between the guard cells is called stomatal, and the entire formation is guard cells with a stomatal gap - stomata.
In plants that live in dry places, the skin is covered with wax and other substances that enhance the plant’s protection from water evaporation. The skin cells of many plants form hairs. They can for a long time remain alive or quickly die and fill with air, forming a woolly or felt cover on the plant. This cover reflects part sun rays and reduces leaf heating.
Young shoots of trees and shrubs are covered with skin. Older ones have no skin. its cells die and slough off. But even before this happens, a multi-layered covering tissue, a cork, forms under the skin. The cork cells are dead, filled with air, and tightly adjacent to each other. With age, the thickness of the cork layer increases.
There are lentils in the cork. They are loosely interconnected cells. Gases pass freely through the intercellular spaces of lentils, so they, like the stomata in the lentils, ensure gas exchange of the integumentary tissues.
Cork on the trunks and branches of trees serves as a kind of case that more reliably protects the internal tissues of plants from the adverse effects of the external environment than a single-layer skin. In most trees, the cork is replaced with age by a crust (bark), consisting of many layers of dead cells. A thick crust even more reliably protects tree trunks from mechanical damage (animal gnawing, forest fires, sudden temperature changes).
Animal integumentary tissues
Multicellular animals, like plants, have integumentary epithelial tissues (epithelium). They cover the body of animals from the outside and line the inside of all hollow organs (vessels, Airways, stomach, intestines). The outer epithelial cells are arranged in one or more layers and fit tightly together. They have a flat, elongated or cylindrical shape. The intercellular substance is poorly developed or absent.
The integumentary tissues of animals perform the same function as those of plants: they protect the body from mechanical damage, contribute to the survival of unfavorable conditions, and participate in gas exchange.
In addition, there is glandular epithelium, the cells of which are part of the glands. They perform a secretory function and secrete special substances (secret): saliva, digestive juices, sweat, milk. The integument of complex animals, such as animals, has multilayered epithelium. It forms the top layer of the skin. As a result of external influences, epithelial cells constantly die and are replaced by new ones.
Sweat and sebaceous glands develop from the outer epithelial cells.
