In any living or plant organism, tissue is formed by cells similar in origin and structure. Any tissue is adapted to perform one or several important functions for an animal or plant organism.

Types of tissues in higher plants

The following types of plant tissues are distinguished:

• educational (meristem);
• integumentary;
• mechanical;
• conductive;
• basic;
• excretory.

All these tissues have their own structural features and differ from each other in the functions they perform.

Fig.1 Plant tissue under a microscope

Educational plant tissue

Educational fabric- This is the primary tissue from which all other plant tissues are formed. It consists of special cells capable of multiple divisions. It is these cells that make up the embryo of any plant.

This tissue is retained in the adult plant. It is located:

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• at the bottom of the root system and at the tops of the stems (ensures plant growth in height and development of the root system) - apical educational tissue;
• inside the stem (ensures the plant grows in width and thickens) - lateral educational tissue;

Plant integumentary tissue

Covering tissue is a protective tissue. It is necessary in order to protect the plant from sudden changes in temperature, from excessive evaporation of water, from microbes, fungi, animals and from all kinds of mechanical damage.

The integumentary tissues of plants are formed by cells, living and dead, that are capable of allowing air to pass through, providing the gas exchange necessary for plant growth.

The structure of plant integumentary tissue is as follows:

• first there is the skin or epidermis, which covers the leaves of the plant, stems and the most vulnerable parts of the flower; skin cells are living, elastic, they protect the plant from excessive moisture loss;
• Next is the cork or periderm, which is also located on the stems and roots of the plant (where the cork layer is formed, the skin dies); The cork protects the plant from adverse environmental influences.

There is also a type of integumentary tissue known as crust. This most durable integumentary tissue, cork, in this case is formed not only on the surface, but also in depth, and its upper layers slowly die off. Essentially, the crust is made up of cork and dead tissue.

Fig. 2 Crust - a type of plant covering tissue

For the plant to breathe, cracks form in the crust, at the bottom of which there are special shoots, lentils, through which gas exchange occurs.

Mechanical plant tissue

Mechanical tissues give the plant the strength it needs. It is thanks to their presence that the plant can withstand strong gusts of wind and do not break under streams of rain or under the weight of fruits.

There are two main types of mechanical fabrics: bast and wood fibers.

Conductive plant tissues

Conductive fabric ensures the transport of water with minerals dissolved in it.

This tissue forms two transport systems:

• upward(from roots to leaves);
• downward(from leaves to all other parts of plants).

The ascending transport system consists of tracheids and vessels (xylem or wood), and vessels are more advanced conductors than tracheids.

In descending systems, the flow of water with photosynthesis products passes through sieve tubes (phloem or phloem).

Xylem and phloem form vascular-fibrous bundles - the “circulatory system” of the plant, which penetrates it completely, connecting it into one whole.

Main fabric

Ground tissue or parenchyma- is the basis of the entire plant. All other types of fabrics are immersed in it. This is living tissue and it performs different functions. It is because of this that its different types are distinguished (information about the structure and functions of different types of basic tissue is presented in the table below).

Rice. 3 The main tissue or parenchyma of the plant

Excretory tissues

The name of this fabric indicates exactly what function it plays. These fabrics help saturate the fruits of plants with oils and juices, and also contribute to the release of a special aroma by the leaves, flowers and fruits. Thus, there are two types of this fabric:

• endocrine tissue;
• Exocrine tissue.

What have we learned?

For the biology lesson, 6th grade students need to remember that animals and plants consist of many cells, which, in turn, arranged in an orderly manner, form one or another tissue. We found out what types of tissues exist in plants - educational, integumentary, mechanical, conductive, basic and excretory. Each tissue performs its own strictly defined function, protecting the plant or providing all its parts with access to water or air.

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Any tissue is a group of cells that are similar in structure and origin, and also perform a common function. All fabrics are divided into 2 large groups:

• simple - consisting of one type of cell;
• complex - consisting of different types of cells, which, in addition to their main ones, also perform additional functions.

The morphological characteristics of tissues (i.e., structural features) depend on the functions they perform. The following types of tissues are distinguished in plants:

• educational,
• integumentary,
• mechanical,
• conductive,
• basic.

Let's look at a brief description of each of them.

Educational

Educational tissues are also called meristems, which is translated from Greek. "meristos" means "divisible". It is easy to guess that their main function is to ensure plant growth through the almost constant division of cells entering the tissue.

The cells themselves are quite small, because they simply do not have time to grow. Among the main features of their structure are thin shells, close adherence of cells to each other, large nuclei, an abundance of mitochondria, vacuoles and ribosomes. Mitochondria act as energy suppliers for various cellular processes, and ribosomes synthesize protein molecules necessary for the formation of new cells.

There are 2 subtypes of meristems:

• Primary - providing primary growth in length. It makes up the embryo of the seed, and in an adult plant this tissue is stored in the tips of the shoots and the tips of the roots.
• Secondary - ensuring the growth of the stem in diameter. This group is divided into apical, lateral, intercalary and wound secondary meristems. They consist of cambium and phellogen.

Integumentary

Integumentary tissues form the surface of the plant body and are found on all organs. Their main function is to ensure the body’s resistance to mechanical stress and sudden temperature fluctuations, as well as protection from excessive evaporation of moisture and the penetration of pathogenic microorganisms.

These fabrics are divided into 3 main types:

• Epidermis (also called epidermis or skin) is a primary tissue made up of a single layer of small transparent cells that fit tightly together. It covers the leaves and young shoots. The surface of this tissue has special formations called stomata, which regulate the processes of gas exchange and water movement throughout the plant body. It is also usually covered with a special cuticle or wax coating, which provides additional protection.
• Periderm is a secondary tissue covering stems and roots. It replaces the epidermis in perennial plants, less often in annual plants. It consists of cork cambium (otherwise called phellogen) - a dead layer of cells, the walls of which are impregnated with a waterproof substance. It is formed by division and differentiation of phellogen inward and outward, resulting in the formation of 2 layers - phelloderm and phellem, respectively. Thus, the periderm has 3 layers: phellem (cork), phellogen, phelloderm. Since the cells of the cork are saturated with suberin - a fat-like substance that does not allow air and water to pass through, as a result the contents of the cells die and they are filled with air. The dense cork layer is a reliable protection of plants from adverse external factors.
• Cork is a tertiary fabric that replaces cork. As a rule, it makes up the bark of trees and some shrubs. It is formed as a result of the fact that new areas of phellogen are laid down in the deep tissues of the cortex, from which, accordingly, new layers of cork are formed. Because of this, the outer tissues are isolated from the central part of the stem, deformed and die, and the surface of the stem is covered with dead tissue from several layers of cork and dead areas of bark. Of course, a thick crust provides greater protection than cork.

Mechanical

These tissues consist of cells with thick membranes. They provide a kind of “framework”, i.e., they maintain the shape of the plant and make it more resistant to mechanical stress. Among the features of these tissues, one can highlight the powerful thickening and lignification of the membranes, the close adjacency of cells to each other and the absence of perforations in their walls. They are most strongly developed in the stems, where they are represented by wood and bast fibers, but they are also present in the central part of the roots. There are 2 types of mechanical fabric:

• Callenchyma - consists of living cells with unevenly thickened membranes, which can significantly strengthen young growing organs. In addition, the cells of this tissue stretch very easily, so they do not interfere with the elongation of the plant.
• Sclerenchyma - consists of elongated cells with evenly thickened membranes, which, moreover, are often lignified, their contents die off in the early stages. The membranes of these cells have very high strength, so they form the tissues of the vegetative organs of land plants, constituting their axial support.

Conductive

Conductive tissues ensure the transport and distribution of water and minerals throughout the plant body. There are 2 main types of such fabrics:

• Xylem (wood) is the main water-conducting tissue. It consists of special vessels - tracheas and tracheids. The first are hollow tubes with through holes. The second are narrow, elongated dead cells with pointed ends and lignified membranes. Xylem is responsible for transporting liquid with minerals dissolved in it by an ascending current - from the roots to the above-ground part of the plant. Also performs a supporting function.
• Phloem (phloem) - represented by sieve tubes, provides a reverse, downward current: it carries nutrients synthesized in the leaves to other parts of the plant, including the roots. It is in close relationship with xylem, forming together with it certain complex groups in plant organs - the so-called vascular bundles.

Basic

Basic tissues (parenchyma), as the name suggests, form the basis of plant organs. They are formed by living thin-walled cells and perform several functions, so they are divided into several varieties. In particular, these are:

• Assimilation - contain a large number of chloroplasts, respectively, are responsible for the processes of photosynthesis and the formation of organic substances. Basically, plant leaves are formed from these tissues; a little less of them are found in young green stems.
• Storage - accumulate useful substances, including proteins and carbohydrates. These are the tissues of roots, fruits, seeds, bulbs, tubers and stems of woody plants.
• Aquifers - accumulate and store water. As a rule, these tissues form the organs of plants growing in dry and hot climates. They can be contained both in leaves (for example, in aloe) and in stems (in cacti).
• Airborne - due to the large number of intercellular spaces filled with air, they transport it to those parts of the body whose communication with the atmosphere is difficult. They are characteristic of aquatic and marsh plants.

As we see, plant tissues are no less diverse and complex than animal tissues. They achieved the greatest specialization in angiosperms: they have up to 80 types of tissues.

The first organisms on Earth were single-celled. The entire body of the organism consisted of just one cell. Later, multicellular organisms appeared, but their bodies consisted of identical cells. And only then did organisms begin to consist not only of identical, but also of different cells. Identical cells in the same organism form tissues. In complex organisms there can be a number of different tissues, so there are a number of different cells.

By the composition of plant tissues, you can determine which group they belong to - algae, mosses, ferns or seed plants.

Tissues contain cells that are similar in their structure and functions. Tissues can differ in the density of cells; in some they can be located very close to each other, forming rows of cells, in others they can lie as desired, not tightly to each other, loosely. The spaces between cells are called intercellular space, or intercellular spaces. The tissue also includes intercellular spaces.

Cells educational fabric divide throughout the life of the plant. The cells of the educational tissue lie tightly to each other; dividing, they form new cells and thereby ensure the growth of the plant not only in length, but also in thickness.

In addition, cells of plant educational tissue are capable of transforming into cells of other tissues.

Responsible for the creation and accumulation of substances main fabric. It is in this tissue that chlorophyll is found, thanks to which organic substances are synthesized from inorganic substances. The main tissue is mainly found in the leaves of plants.

However, the main tissues in which the supply of nutrients occurs are in seeds, modified roots (potato tuber), stems (bulb), etc.

Performs a protective function cover tissue. It protects all plant organs from the outside from drying out, damage, and overheating. In the skin of leaves and shoots, the cells of the integumentary tissue are tightly closed together; they have a transparent cell wall to allow light to pass through. In roots and stems, the covering tissue can become suberized, turning into a cork.

Thanks to conductive tissue substances can move throughout the plant. Substances move in aqueous solutions that flow through the cells of conducting tissues. In higher plants, conducting tissue consists of vessels, tracheids and sieve tubes. Conducting tissues have pores and openings that allow the movement of substances between cells.

Conductive tissue is a branched network connecting all plant organs. Thus, all parts of the plant are combined into a single system.

Mechanical fabric allows plants to withstand various loads, such as wind. Mechanical tissue cells have very strong cell walls.

The existence of different tissues is due to the fact that plant cells on land have to perform different functions. The root is in the soil and absorbs the water solution, also holding the plant in the soil. The leaves are exposed to light and are responsible for the synthesis of organic substances. The stem connects different parts of the plant with each other.

Plant and animal tissues

You already know that all living organisms, according to their structure, are divided into two large groups: unicellular and multicellular.

The bodies of unicellular organisms consist of one single cell in which all life processes take place.

The situation is different in multicellular organisms. Their bodies are made up of many different cells. Thus, there are more than 100 trillion cells in the human body. Each cell of a multicellular organism has its own “specialty”, that is, it performs a strictly defined function - work. Some serve as support for the body, others ensure the movement of substances, digestion, reproduction of the body and many other functions.

A group of cells similar in size, structure and functions form tissue. Cells of the same tissue are connected to each other by an intercellular substance.

Let's look inside the plant and see how its tissues are arranged. Here in front of us are the tips of the root and the shoot. They are formed by small, constantly dividing cells with large nuclei; there are no vacuoles in their cytoplasm. This is an educational tissue; the division of its cells ensures the growth of the plant. For example, the entire embryo of a plant consists of it.

They protect plants from adverse influences and from damage to integumentary tissues. They are formed by both living and dead cells. The thick and durable shells of such dead cells do not allow either water or air to pass through. They are very firmly connected to each other. The integumentary tissue forms, for example, the skin of a leaf, the cork layers of tree trunks.

Performs integumentary tissue and other functions. For example, it connects the plant with the external environment: through special formations - stomata and lentils - the plant breathes and evaporates water.

Mechanical tissue provides support to the plant and its organs. Its cells have thickened, lignified shells, and their living contents are often absent. You can get an idea of ​​the strength of mechanical tissue by breaking a walnut shell or an apricot kernel - they contain special stony cells. And in the stem, elongated cells - fibers - play a supporting role.

Water and mineral and organic substances dissolved in it move through conducting tissues. Conductive tissue cells can be either living or dead. In appearance, they are very similar to vessels or tubes that stretch through the root and stem into the leaf.

The pulp of the leaf and fruit, the soft parts of the flower, the main mass of the bark and core of the stems and roots form the main tissue. Its functions are very diverse, but the main one is the formation and accumulation of nutrients. The cells of the leaf pulp contain chloroplasts - organelles that participate in the formation of nutrients during the process of photosynthesis.

Now let's look at the structural features of the tissues of animal organisms. There are four types of tissues - epithelial, connective, muscle and nervous.

The outer surface of the body of animals, as well as the cavities of internal organs, for example the oral cavity, the cavity of the stomach, and intestines, is lined with epithelial tissue. Its cells adhere very tightly to each other, and the intercellular substance is almost absent. This structure provides protection to underlying tissues from drying out, penetration of microbes, and mechanical damage. Epithelial tissue also participates in the formation of glands - salivary, sweat, pancreas, liver and others, which secrete substances important for the body.

The supporting and protective function in the body of animals is performed by connective tissue. It also largely determines the shape of their body, can serve as an energy depot and protect the body from heat loss. This type includes bone tissue, cartilage, adipose tissue, blood and others. Despite the great diversity, all types of connective tissue are united by one feature - the presence of a large amount of intercellular substance. It can be dense, as in bone tissue, loose, as in the tissues that fill the space between organs, and liquid, as in blood.

An important feature of animals is their ability to move. The movement of most animals is the result of muscle contractions. Muscles are made up of muscle tissue. There are smooth and striated muscle tissues. Their main property is excitability and contractility.

Smooth muscle cells are mononuclear; they contract very slowly, but can remain contracted for a long time. It is smooth muscles that ensure prolonged closure of the valves of mollusk shells, narrowing and dilating of blood vessels in humans.

Striated muscle consists of multinucleated cells with striations, hence the name of the tissue. It is with their contractions that the rapid movements of numerous arthropods (insects, crayfish, spiders) and vertebrates are associated. Remember the swift flight of a dragonfly, a swallow, the running of an antelope, a cheetah!

Striated muscle can contract instantly - a thousand times faster than smooth muscle.

^ Nerve tissue forms the nervous system of an animal. Its basis is a nerve cell. It consists of a body and numerous processes of varying lengths. One of them is usually particularly long, it can reach a length from several centimeters to several meters, such as a giraffe. The main property of a nerve cell is excitability and conductivity.

The plant embryo consists entirely of educational tissue. As it develops, most of it is transformed into other types of tissue, but even in the oldest tree educational tissue remains: it is preserved at the tops of all shoots, in all buds, at the tips of roots, in the cambium - the cells of the stem that ensure its growth in thickness.

The integumentary tissue of the leaf - the skin - secretes a waxy substance that prevents the evaporation of water from the surface of the leaf.

In the embryos of all vertebrates, the skeleton consists of cartilage, which is replaced by bone tissue as it develops. The exception is sharks and rays; their skeleton remains cartilaginous until the end of their lives.

Muscle tissue contains a large number of parallel contractile fibers. It is their contraction, during which they become shorter and thicker, that allows the muscle to perform mechanical work.

Animals have four types of tissue:

Epithelial

Connective

Muscular

Moreover, a certain type of fabric may have its own subtypes.

Animal organs are made up of tissues. One organ may contain several different tissues. The same type of tissue can be found in different organs. The tissue is made up not only of cells, but also of intercellular substance, which is usually secreted by the cells of the tissue itself.

Animal epithelial tissue

Epithelium forms the outer covering of animals and also lines the cavities of internal organs. Epithelial (integumentary) tissue is found in the stomach cavity, intestines, oral cavity, lungs, bladder, etc.

The cells of animal epithelial tissue are tightly adjacent to each other, there is almost no intercellular substance. Cells form one or more rows.

Epithelial tissue may contain various glands that secrete secretions. For example, in the epithelium of the skin there are sebaceous and sweat glands, in the stomach there are glands that secrete certain substances.

Epithelial tissue performs protective, secretory, absorption, excretory and other functions.

Animal connective tissue

Animal connective tissue forms bones, cartilage, ligaments, tendons, and fat deposits. Blood is also a connective tissue.

A feature of connective tissue is a large amount of intercellular substance. Cells are scattered in this substance.

Connective tissue performs a supporting, protective function in the animal’s body, connecting various organ systems. For example, blood carries oxygen from the lungs to the tissues. Carries carbon dioxide away from the tissues into the lungs. Harmful substances are delivered by blood to the excretory system. Nutrients are absorbed into the blood in the intestines and distributed throughout the body.

Animal muscle tissue

The muscle tissue of animals is responsible for the movement of both the organism itself in space and for the mechanical work of its internal organs. Muscle cells are able to contract and relax in response to signals from the nervous system.

There are three types of muscle tissue: smooth (part of the internal organs), skeletal striated, cardiac striated.

Animal nervous tissue

The cells of the nervous tissue of animals have a body, short and long processes that are connected to each other. Signals of electrical and chemical nature are transmitted through these cells. From receptors and sensory organs, signals go to the animal’s spinal cord and brain, where they are processed. In response, there are feedback signals that contract certain muscles.

Nervous tissue ensures the coordinated functioning of all organs and systems of the body and is responsible for the response to environmental influences.

The extraordinary diversity of living beings on the planet forces us to find different criteria for their classification. Thus, they are classified as cellular and non-cellular forms of life, since cells are the structural unit of almost all known organisms - plants, animals, fungi and bacteria, while viruses are non-cellular forms.

Unicellular organisms

Depending on the number of cells that make up the organism and the degree of their interaction, unicellular, colonial and multicellular organisms are distinguished. Despite the fact that all cells are morphologically similar and are capable of performing normal cell functions (metabolism, maintaining homeostasis, development, etc.), the cells of unicellular organisms perform the functions of an entire organism. Cell division in unicellular organisms entails an increase in the number of individuals, and in their life cycle there are no multicellular stages. In general, unicellular organisms have the same cellular and organismal levels of organization. The vast majority of bacteria, some animals (protozoa), plants (some algae) and fungi are unicellular. Some taxonomists even propose to separate unicellular organisms into a special kingdom - protists.

Colonial organisms

Colonial are organisms in which, during the process of asexual reproduction, daughter individuals remain connected to the mother organism, forming a more or less complex association - a colony. In addition to colonies of multicellular organisms, such as coral polyps, there are also colonies of unicellular organisms, in particular pandorina and eudorina algae. Colonial organisms apparently were an intermediate link in the process of the emergence of multicellular organisms.

Multicellular organisms

Multicellular organisms undoubtedly have a higher level of organization than single-celled organisms, since their body is formed by many cells. Unlike colonial organisms, which can also have more than one cell, in multicellular organisms the cells are specialized to perform various functions, which is reflected in their structure. The price for this specialization is the loss of the ability of their cells to exist independently, and often to reproduce their own kind. The division of a single cell leads to the growth of a multicellular organism, but not to its reproduction. Ontogenesis of multicellular organisms is characterized by the process of fragmentation of a fertilized egg into many blastomere cells, from which an organism with differentiated tissues and organs is subsequently formed. Multicellular organisms are usually larger than unicellular ones. An increase in body size in relation to their surface contributed to the complexity and improvement of metabolic processes, the formation of the internal environment and, ultimately, provided them with greater resistance to environmental influences (homeostasis). Thus, multicellular organisms have a number of advantages in organization compared to unicellular organisms and represent a qualitative leap in the process of evolution. Few bacteria, most plants, animals and fungi are multicellular.

Cell differentiation in multicellular organisms leads to the formation of tissues and organs in plants and animals (except sponges and coelenterates).

Tissues and organs

Tissue is a system of intercellular substance and cells that are similar in structure, origin and perform the same functions.

There are simple tissues, consisting of cells of one type, and complex ones, consisting of several types of cells. For example, the epidermis in plants consists of the integumentary cells themselves, as well as guard and subsidiary cells that form the stomatal apparatus.

Organs are formed from tissues. The organ includes several types of tissues, related structurally and functionally, but usually one of them predominates. For example, the heart is formed mainly by muscle tissue, and the brain by nervous tissue. The leaf blade of a plant includes integumentary tissue (epidermis), main tissue (chlorophyll-bearing parenchyma), conductive tissues (xylem and phloem), etc. However, the main tissue predominates in the leaf.

Organs that perform general functions form organ systems. Plants are divided into educational, integumentary, mechanical, conductive and basic tissues.

Plant tissues

Educational fabrics

Cells of educational tissues (meristems) retain the ability to divide for a long time. Thanks to this, they take part in the formation of all other types of tissues and ensure plant growth. Apical meristems are located at the tips of shoots and roots, and lateral meristems (for example, the cambium and pericycle) are located inside these organs.

Integumentary tissues

Integumentary tissues are located at the border with the external environment, i.e. on the surface of roots, stems, leaves and other organs. They protect the internal structures of the plant from damage, low and high temperatures, excessive evaporation and drying out, penetration of pathogens, etc. In addition, integumentary tissues regulate gas exchange and water evaporation. The integumentary tissues include the epidermis, periderm and crust.

Mechanical fabrics

Mechanical tissues (collenchyma and sclerenchyma) perform supporting and protective functions, giving strength to organs and forming the “internal skeleton” of the plant.

Conductive fabrics

Conductive tissues ensure the movement of water and substances dissolved in it in the plant body. Xylem delivers water with dissolved minerals from the roots to all plant organs. Phloem transports solutions of organic substances. Xylem and phloem are usually located side by side, forming layers or vascular bundles. In the leaves they can be easily seen in the form of veins.

Main fabrics

Ground tissues, or parenchyma, make up the bulk of the plant body. Depending on the location in the plant’s body and the characteristics of its habitat, the main tissues are capable of performing various functions - carrying out photosynthesis, storing nutrients, water or air. In this regard, chlorophyll-bearing, storage, water-bearing and air-bearing parenchyma are distinguished.

As you remember from the 6th grade biology course, plants have vegetative and generative organs. The vegetative organs are the root and shoot (stem with leaves and buds). Generative organs are divided into organs of asexual and sexual reproduction.

The organs of asexual reproduction in plants are called sporangia. They are located singly or combined into complex structures (for example, sori in ferns, spore-bearing spikelets in horsetails and mosses).

The organs of sexual reproduction ensure the formation of gametes. Male (antheridia) and female (archegonia) organs of sexual reproduction develop in mosses, horsetails, mosses and ferns. Gymnosperms are characterized only by archegonia that develop inside the ovule. Antheridia do not form in them, and male reproductive cells - sperm - are formed from the generative cell of the pollen grain. Flowering plants lack both antheridia and archegonia. Their generative organ is the flower, in which the formation of spores and gametes, fertilization, and the formation of fruits and seeds occur.

Animal tissue

Epithelial tissue

Epithelial tissue covers the outside of the body, lines the body cavities and the walls of hollow organs, and is part of most glands. Epithelial tissue consists of cells tightly adjacent to each other; the intercellular substance is not developed. The main functions of epithelial tissues are protective and secretory.

Connective tissues

Connective tissues are characterized by a well-developed intercellular substance in which cells are located singly or in groups. The intercellular substance, as a rule, contains a large number of fibers. Tissues of the internal environment are the most diverse group of animal tissues in structure and function. This includes bone, cartilage and adipose tissue, connective tissue itself (dense and loose fibrous), as well as blood, lymph, etc. The main functions of the tissues of the internal environment are supporting, protective, and trophic.

Muscle tissue

Muscle tissue is characterized by the presence of contractile elements - myofibrils, located in the cytoplasm of cells and providing contractility. Muscle tissue performs a motor function.

Nervous tissue

Nerve tissue consists of nerve cells (neurons) and glial cells. Neurons are capable of being excited in response to various factors, generating and conducting nerve impulses. Glial cells provide nutrition and protection to neurons and the formation of their membranes.

Animal tissues participate in the formation of organs, which, in turn, are combined into organ systems. In the body of vertebrates and humans, the following organ systems are distinguished: skeletal, muscular, digestive, respiratory, urinary, reproductive, circulatory, lymphatic, immune, endocrine and nervous. In addition, animals have various sensory systems (visual, auditory, olfactory, gustatory, vestibular, etc.), with the help of which the body perceives and analyzes various stimuli from the external and internal environment.

Any living organism is characterized by obtaining building and energy material from the environment, metabolism and energy conversion, growth, development, ability to reproduce, etc. In multicellular organisms, various vital processes (nutrition, respiration, excretion, etc.) are realized through interaction certain tissues and organs. At the same time, all life processes are controlled by regulatory systems. Thanks to this, a complex multicellular organism functions as a single whole.

In animals, regulatory systems include the nervous and endocrine. They ensure the coordinated functioning of cells, tissues, organs and their systems, determine the body’s holistic reactions to changes in external and internal environmental conditions, aimed at maintaining homeostasis. In plants, vital functions are regulated with the help of various biologically active substances (for example, phytohormones).

Thus, in a multicellular organism, all cells, tissues, organs and organ systems interact with each other and function harmoniously, thanks to which the organism is an integral biological system.

The body of many living organisms consists of tissues. Exceptions are all unicellular organisms, as well as some multicellular organisms, for example, which include algae and lichens. In this article we will look at the types of fabrics. Biology studies this topic, namely its section - histology. The name of this industry comes from the Greek words "fabric" and "knowledge". There are many types of fabrics. Biology studies both plants and animals. They have significant differences. Biology has been studied for quite some time. For the first time they were described even by such ancient scientists as Aristotle and Avicenna. Biology continues to study tissues and types of tissues - in the 19th century they were studied by such famous scientists as Moldenhauer, Mirbel, Hartig and others. With their participation, new types of cell aggregates were discovered and their functions were studied.

Types of tissues - biology

First of all, it should be noted that the tissues that are characteristic of plants are not characteristic of animals. Therefore, biology can divide tissue types into two large groups: plant and animal. Both combine a large number of varieties. We will consider them further.

Types of animal tissues

Let's start with what is closer to us. Since we belong to the animal kingdom, our body consists precisely of tissues, the varieties of which will now be described. Types of animal tissues can be grouped into four large groups: epithelial, muscle, connective and nervous. The first three are divided into many varieties. Only the last group is represented by only one type. Next, we will consider all types of tissues, the structure and functions that are characteristic of them, in order.

Nervous tissue

Since it only comes in one variety, let's start with that one. The cells of this tissue are called neurons. Each of them consists of a body, an axon and dendrites. The latter are processes through which an electrical impulse is transmitted from cell to cell. A neuron has one axon - it is a long process, there are several dendrites, they are smaller than the first one. The cell body contains the nucleus. In addition, the cytoplasm contains the so-called Nissl bodies - an analogue of the endoplasmic reticullum, mitochondria, which produce energy, as well as neurotubules, which are involved in conducting impulses from one cell to another.

Depending on their functions, neurons are divided into several types. The first type is sensory, or afferent. They conduct impulses from the sense organs to the brain. The second type of neurons is associative, or switching. They analyze the information received from the senses and develop a response impulse. These types of neurons are found in the brain and spinal cord. The last type is motor, or afferent. They conduct impulses from associative neurons to organs. Nervous tissue also contains intercellular substance. It performs very important functions, namely, it ensures a fixed location of neurons in space, and participates in the removal of unnecessary substances from the cell.

Epithelial

These are types of tissues whose cells are tightly adjacent to each other. They can have a variety of shapes, but are always located close. All the different types of tissues in this group are similar in that they have little intercellular substance. It is mainly presented in the form of a liquid, in some cases it may not be present. These are types of body tissues that provide its protection and also perform a secretory function.

This group includes several varieties. These are flat, cylindrical, cubic, sensory, ciliated and glandular epithelium. From the name of each one you can understand what form of cells they are made of. Different types of epithelial tissues also differ in their location in the body. Thus, the flat one lines the cavities of the upper organs of the digestive tract - the oral cavity and esophagus. Columnar epithelium is found in the stomach and intestines. Cubic can be found in the renal tubules. The sensory one lines the nasal cavity; it contains special villi that provide the perception of odors. Ciliated epithelial cells, as its name implies, have cytoplasmic cilia. This type of tissue lines the airways, which are located below the nasal cavity. The cilia that each cell has perform a cleansing function - they to some extent filter the air that passes through the organs covered by this type of epithelium. And the last type of this group of tissues is glandular epithelium. Its cells perform a secretory function. They are found in the glands, as well as in the cavities of some organs, such as the stomach. Cells of this type of epithelium produce hormones, gastric juice, milk, sebum and many other substances.

Muscle tissue

This group is divided into three types. The muscle is smooth, striated and cardiac. All muscle tissues are similar in that they consist of long cells - fibers; they contain a very large number of mitochondria, since they need a lot of energy to carry out movements. lines the cavities of internal organs. We cannot control the contraction of such muscles ourselves, since they are innervated by the autonomic nervous system.

Cells of striated muscle tissue are distinguished by the fact that they contain more mitochondria than the first. This is because they require more energy. Striated muscles can contract much faster than smooth muscles. Skeletal muscles are made of it. They are innervated by the somatic nervous system, so we can consciously control them. Cardiac muscle tissue combines some of the characteristics of the first two. It is capable of contracting as actively and quickly as the striated one, but is innervated by the autonomic nervous system, just like the smooth one.

Connective tissue types and their functions

All tissues of this group are characterized by a large amount of intercellular substance. In some cases it appears in a liquid aggregate state, in some - in a liquid state, sometimes - in the form of an amorphous mass. Seven types belong to this group. These are dense and loose fibrous, bone, cartilage, reticular, fatty, blood. The first type is dominated by fibers. It is located around the internal organs. Its functions are to give them elasticity and protect them. In loose fibrous tissue, the amorphous mass predominates over the fibers themselves. It completely fills the gaps between the internal organs, while dense fibrous forms only peculiar shells around the latter. She also plays a protective role.

Bone and form the skeleton. It performs a supporting and partly protective function in the body. In the cells and intercellular substance of bone tissue, phosphates and calcium compounds predominate. The exchange of these substances between the skeleton and blood is regulated by hormones such as calcitonin and parathyrotropin. The first maintains the normal condition of bones by participating in the conversion of phosphorus and calcium ions into organic compounds stored in the skeleton. And the second, on the contrary, with a lack of these ions in the blood provokes their production from skeletal tissues.

Blood contains a lot of liquid intercellular substance, it is called plasma. Its cells are quite peculiar. They are divided into three types: platelets, erythrocytes and leukocytes. The former are responsible for blood clotting. During this process, a small blood clot is formed, which prevents further blood loss. Red blood cells are responsible for transporting oxygen throughout the body and providing it to all tissues and organs. They may contain aglutinogens, which exist in two types - A and B. Blood plasma may contain alpha or beta aglutinins. They are antibodies to aglutinogens. These substances are used to determine the blood type. In the first group, no aglutinogens are observed on the erythrocytes, and in the plasma there are two types of aglutinins at once. The second group has aglutinogen A and aglutinin beta. The third is B and alpha. There are no aglutinins in the plasma of the fourth, but aglutinogens A and B are present on the red blood cells. If A meets alpha or B meets beta, the so-called aglutination reaction occurs, as a result of which the red blood cells die and blood clots form. This can happen if you transfuse blood of the wrong type. Considering that only red blood cells are used during transfusion (plasma is screened out at one of the stages of processing donor blood), then a person with the first group can only be transfused with blood of his own group, with the second - blood of the first and second groups, with the third - with the first and third groups, from the fourth - any group.

Also, D antigens may be present on red blood cells, which determines the Rh factor; if they are present, the latter is positive; if absent, it is negative. Lymphocytes are responsible for immunity. They are divided into two main groups: B lymphocytes and T lymphocytes. The former are produced in the bone marrow, the latter - in the thymus (gland located behind the sternum). T lymphocytes are divided into T-inducers, T-helpers and T-suppressors. Reticular connective tissue consists of a large amount of intercellular substance and stem cells. Blood cells are formed from them. This tissue forms the basis of the bone marrow and other hematopoietic organs. There are also cells that contain lipids. It performs a reserve, thermal insulation and sometimes protective function.

How do plants work?

These organisms, like animals, consist of aggregates of cells and intercellular substance. We will describe the types of plant tissues further. All of them are divided into several large groups. These are educational, integumentary, conductive, mechanical and basic. The types of plant tissues are numerous, as several belong to each group.

Educational

These include apical, lateral, insertional and wound. Their main function is to ensure plant growth. They consist of small cells that actively divide and then differentiate to form any other type of tissue. The apical ones are located at the tips of the stems and roots, the lateral ones - inside the stem, under the integumentary ones, the intercalary ones - at the bases of the internodes, the wound ones - at the site of damage.

Integumentary

They are characterized by thick cell walls composed of cellulose. They play a protective role. There are three types: epidermis, crust, plug. The first covers all parts of the plant. It may have a protective waxy coating; it also contains hairs, stomata, cuticle, and pores. The crust is distinguished by the fact that it does not have pores; in all other characteristics it is similar to the epidermis. Cork is the dead tissue that forms the bark of trees.

Conductive

These tissues come in two varieties: xylem and phloem. Their functions are the transport of substances dissolved in water from the root to other organs and vice versa. Xylem is formed from vessels formed by dead cells with hard shells; there are no transverse membranes. They transport liquid upward.

Phloem - sieve tubes - living cells that do not have nuclei. The transverse membranes have large pores. With the help of this type of plant tissue, substances dissolved in water are transported downward.

Mechanical

They also come in two types: and sclerenchyma. Their main task is to ensure the strength of all organs. Collenchyma is represented by living cells with lignified membranes that fit tightly to each other. Sclerenchyma consists of elongated dead cells with hard membranes.

Basic

As their name implies, they form the basis of all plant organs. They are assimilation and spare. The first are found in the leaves and green part of the stem. Their cells contain chloroplasts, which are responsible for photosynthesis. Organic substances accumulate in the storage tissue, in most cases it is starch.