The body of many living organisms is made up of tissues. The exceptions are all unicellular, as well as some multicellular, for example, lower plants, which include algae, as well as lichens. In this article, we will look at the types of fabrics. Biology studies this topic, namely its section - histology. The name of this branch comes from the Greek words "cloth" and "knowledge". There are many types of fabrics. Biology studies both plants and animals. They have significant differences. Tissues, types of tissues biology has been studying for a long 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 further - in the 19th century they were studied by such famous scientists as Moldengauer, 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 tissues that are characteristic of plants are not characteristic of animals. Therefore, biology can divide the types of tissues into two large groups: plant and animal. Both combine a large number of varieties. Them wenext and consider.
Types of animal tissue
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 combined into four large groups: epithelial, muscle, connective and nervous. The first three are subdivided 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 it. The cells in this tissue are called neurons. Each of them consists of a body, an axon and dendrites. The latter are processes along 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 so-called Nissl bodies are located in the cytoplasm - an analogue of the endoplasmic reticulum, mitochondria that produce energy, as well as neurotubules that are involved in conducting an impulse 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 are associative, or switching. They analyze the information that came from the senses, and develop a response impulse. These types of neurons are found in the brain andspinal cord. The last variety is motor, or efferent. They conduct an impulse from associative neurons to organs. Also in the nervous tissue there is an intercellular substance. It performs very important functions, namely, it provides a fixed arrangement of neurons in space, participates in the removal of unnecessary substances from the cell.
Epithelial
These are types of tissues whose cells fit tightly to each other. They can have a variety of shapes, but are always close. All different types of tissues of this group are similar in that there is little intercellular substance in them. It is mainly presented in the form of a liquid, in some cases it may not be. These are the types of body tissues that provide protection and also perform a secretory function.
This group combines several varieties. This is a flat, cylindrical, cubic, sensory, ciliated and glandular epithelium. From the name of each one can understand what form of cells they consist of. Different types of epithelial tissues differ in their location in the body. So, flat lines the cavities of the upper organs of the digestive tract - the oral cavity and esophagus. Cylindrical epithelium is found in the stomach and intestines. Cubic can be found in the renal tubules. The sensory one lines the nasal cavity; there are special villi on it that provide the perception of odors. The cells of the ciliated epithelium, as its name implies, have cytoplasmic cilia. This type of fabric is linedairways that are below the nasal cavity. The cilia that each cell has perform a cleansing function - to some extent they filter the air that passes through the organs covered by this type of epithelium. And the last type of this group of tissues is the glandular epithelium. Its cells perform a secretory function. They are found in the glands, as well as in the cavity of some organs, such as the stomach. The cells of this type of epithelium produce hormones, ear wax, 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. Smooth muscle tissue 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 differ in that they contain more mitochondria than the first. This is because they require more energy. Striated muscles can contract much faster than smooth muscles. It is made up of skeletal muscles. They are innervated by the somatic nervous system, so we can consciously control them. Muscular heart tissue combines some of the characteristics of the first two. She is also able to activelycontract quickly, like striated, but innervated by the autonomic nervous system, just like smooth.
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 state of aggregation, in some - in a liquid, sometimes - in the form of an amorphous mass. Seven types belong to this group. It is dense and loose fibrous, bone, cartilaginous, reticular, fatty, blood. In the first variety, fibers predominate. 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 cartilage tissues form the skeleton. It performs a supporting function in the body and partly protective. Inorganic substances predominate in the cells and intercellular substance of the bone tissue, mainly phosphates and calcium compounds. The exchange of these substances between the skeleton and blood is regulated by hormones such as calcitonin and parathyroid hormone. The first maintains the normal state of the bones, 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 receipt from the tissues of the skeleton.
Blood contains a lot of liquidintercellular substance, it is called plasma. Her 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 agglutinogens, which exist in two types - A and B. In the blood plasma, the content of alpha or beta agglutinins is possible. They are antibodies to agglutinogens. These substances are used to determine the blood type. In the first group, agglutinogens are not observed on erythrocytes, and agglutinins of two types are present in the plasma at once. The second group has agglutinogen A and agglutinin beta. The third is B and alpha. There are no agglutinins in the plasma of the fourth, but both A and B agglutinogens are on the erythrocytes. If A meets alpha or B with beta, the so-called agglutination reaction occurs, as a result of which the erythrocytes die and blood clots form. This can happen if you transfuse the wrong type of blood. Considering that only erythrocytes 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 the blood of his own group, with the second - the blood of the first and second groups, with the third - the first and third groups, from the fourth - any group.
Also, erythrocytes can contain antigens D, which determines the Rh factor, if present, the latter is positive, if absent - negative. Lymphocytesresponsible for immunity. They are divided into two main groups: B-lymphocytes and T-lymphocytes. The first are produced in the bone marrow, the second - in the thymus (a 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. They form blood cells. This tissue forms the basis of the bone marrow and other hematopoietic organs. There is also adipose tissue, the cells of which contain lipids. It performs a spare, heat-insulating and sometimes protective function.
How are plants arranged?
These organisms, like animals, consist of sets 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, since several belong to each group.
Educational
These include apical, lateral, insertion and wound. Their main function is to ensure plant growth. They are made up 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 are inside the stem, under the coverslips, the intercalary ones are at the bases of the internodes, the wound ones are at the site of damage.
Integuments
They are characterized by thick cell walls made of cellulose. They play a protective role. There are threespecies: epidermis, cork, cork. The first covers all parts of the plant. It may have a protective wax coating, it also has hairs, stomata, cuticles, and pores. The crust differs in that it has no pores, in all other characteristics it is similar to the epidermis. Cork is the dead covering 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 upwards.
Phloem - sieve tubes - living cells in which there are no nuclei. The transverse membranes have large pores. With the help of this type of plant tissue, substances dissolved in water are transported down.
Mechanical
They also come in two types: collenchyma and sclerenchyma. Their main task is to ensure the strength of all organs. Collenchyma is represented by living cells with lignified shells that fit tightly to each other. Sclerenchyma consists of elongated dead cells with hard shells.
Basic
As their name implies, they form the basis of all plant organs. They are assimilation and reserve. The first are found in the leaves and the green part of the stem. Their cells contain chloroplasts, which are responsible for photosynthesis. in storage tissueorganic matter accumulates, in most cases it is starch.
