Organism short definition. What is an organism in biology? The concept of "human body"
An organism is an independently existing unit of the organic world, which is a self-regulating system that reacts as a whole to various changes in the external environment. An organism can exist only with constant interaction with its external environment and self-renewal as a result of such interaction. As I. M. Sechenov emphasized, “an organism without an external environment that supports its existence is impossible.”
Characteristic of any organism is a certain organization of its structures. In the simplest living organisms - viruses - there is only an organization of its constituent protein molecules and nucleic acids. Here we can talk about the molecular level of organization of the body. More highly organized unicellular organisms, such as paramecia, are characterized by a more complex structure: the nucleus, mitochondria, surface and intraprotoplasmic membranes, and vacuoles differentiate inside the cell. There is already a supramolecular, cellular level of organization at which there is some separation, differentiation of the functions of various intracellular formations. For example, the motor function is carried out by intracellular contractile fibrils, flagella and cilia; the functions of digestion and excretion in some cells are carried out by vacuoles, etc.
In multicellular organisms, in the course of their evolutionary development, cell differentiation occurs, i.e., differences appear in their size, shape, structure, and functions. From identically differentiated cells, tissues are formed, the characteristic property of which is structural association, morphological and functional commonality and interaction of cells. Different tissues are specialized in their functions, that is, they are adapted to perform different life processes. Thus, muscle tissue is specialized in the performance of a motor function, and its characteristic property is contractility, glandular tissue is specialized in the formation and release of certain chemical compounds (hormones, enzymes, etc.) by its cells. Being adapted to perform a certain type of activity, highly differentiated tissue cells at the same time perform functions common to all cells: metabolism, nutrition, respiration, excretion. The presence of interaction between the cells that form the tissue, the complexity of the structure and the specialization of tissue functions determine their morphological and functional originality, which is the basis for distinguishing the tissue level of organization of a living organism.
At a certain stage of the species and individual development of organisms, organs are formed, built from various tissues. Organs are anatomical formations characterized by a peculiar structural and functional association of different tissues. They are the working apparatuses of the body, specialized in the performance of complex activities necessary for the existence of a holistic organism. So, the heart performs the function of a pump that pumps blood from veins to arteries, the kidneys - the function of excreting end products of metabolism from the body and the function of maintaining a constant concentration of electrolytes in the blood, the bone marrow - the function of hematopoiesis, etc.
The presence of structurally and functionally different organs in the body allows us to talk about the organ level of its organization.
Sets of organs involved in the performance of any complex act of activity form anatomical or functional associations - organ systems. These include the nervous and endocrine systems that regulate the activity of all organs of the body, and the systems of organs of locomotion (movement in space), respiration, circulation, digestion, excretion, reproduction. Among all these systems, the nervous system, which unites and regulates the state and activity of all other body systems and determines its behavior in the external environment, is of particular importance in the whole organism. The presence of organ systems, each of which is specialized in performing some kind of activity of the organism as a whole, determines the systemic level of organization.
Each of the listed levels of organization of living organisms is characterized by its own specific physiological patterns inherent in it, which cannot be understood by studying other levels. To elucidate the processes occurring at different levels of the organization of a living organism, various methodological approaches and various instrumental techniques are required. It should be emphasized that in order to understand the functions of higher organisms, it is necessary to study all - molecular, cellular, tissue, organ and system - levels of organization of the organism and synthesize all the information that researchers receive in this case. This is due to the fact that, having a complex organization, a living organism is a single whole in which the activity of all its structures, cells, tissues, organs and their systems is coordinated and subordinated to this whole.
What is an organism called and how does it differ from other objects in nature? This concept is understood as a living body, which has a combination of various properties. It is they who distinguish the organism from inanimate matter. Translated from Latin, organismus means “I communicate a slender appearance”, “I arrange”. The name itself implies a certain structure of any organism. Biology deals with this scientific category. Living organisms amaze with their diversity. As individuals, they are part of species and populations. In other words, it is a structural unit of a certain standard of living. To understand what is called an organism, one should consider it from different aspects.
General classification
An organism, the definition of which quite fully explains its essence, consists of cells. Specialists distinguish such non-systematic categories of these objects:
Unicellular;
Multicellular.
In a separate group, such an intermediate category between them as colonies of unicellular organisms is distinguished. They are also divided in a general sense into non-nuclear and nuclear. For ease of study, all these objects are divided into numerous groups. Thanks to this division into categories, living organisms (biology grade 6) are summarized in an extensive classification.
The concept of a cell
The definition of the concept of "organism" is inextricably linked with such a category as a cell. It is the basic unit of life. It is the cell that is the real carrier of all the properties of a living organism. In nature, only viruses that are non-cellular form do not have them in their structure. This elementary unit of vital activity and structure of living organisms has the whole set of properties and the mechanism of metabolism. The cell is capable of independent existence, development and self-reproduction.
Many bacteria and protozoa, which are a single-celled organism, and multicellular fungi, plants, animals, consisting of many of these vital activity units, easily fit into the concept of a living organism. Different cells have their own structure. Thus, the composition of prokaryotes includes such organelles as a capsule, plasmalemma, ribosomes, cytoplasm, plasmid, nucleoid, flagellum, pili. Eukaryotes have the following organelles: nucleus, nuclear envelope, ribosomes, lysosomes, mitochondria, vacuoles, vesicles, cell membrane.
The biological definition of "organism" studies a whole section of this science. Cytology deals with the structure and processes of their vital activity. More recently it has been called
unicellular organisms
The concept of "unicellular organism" implies a non-systemic category of objects, the body of which has only one cell. It includes:
Prokaryotes that do not have a well-formed cell nucleus and other internal organelles with membranes. They lack a nuclear envelope. They have an osmotrophic and autotrophic type of nutrition (photosynthesis and chemosynthesis).
Eukaryotes are cells that contain nuclei.
It is generally accepted that unicellular organisms were the first living objects on our planet. Scientists are sure that the most ancient of them were archaea and bacteria. Protists are also often called unicellular - eukaryotic organisms that are not included in the categories of fungi, plants and animals.
Multicellular organisms
A multicellular organism, the definition of which is closely related to the formation of a single whole, is much more complicated than unicellular objects. This process consists of the differentiation of various structures, which include cells, tissues and organs. The formation of a multicellular organism includes the separation and integration of different functions in ontogenesis (individual) and phylogenesis (historical development).
Multicellular organisms consist of many cells, a significant part of which differ in structure and function. The only exceptions are stem cells (in animals) and cambial cells (in plants).
Multicellularity and coloniality
In biology, there are multicellular organisms and colonies of unicellular organisms. Despite some similarities between these living objects, there are fundamental differences between them:
A multicellular organism is a community of many different cells that have their own structure and special functions. His body is made up of different tissues. Such an organism is characterized by a higher level of cell integration. They are distinguished by their diversity.
Colonies of unicellular organisms consist of identical cells. They are almost impossible to separate into fabrics.
The boundary between coloniality and multicellularity is fuzzy. In nature, there are living organisms, for example, volvox, which in their structure are a colony of unicellular organisms, but at the same time they contain somatic and generative cells that differ from each other. It is believed that the first multicellular organisms appeared on our planet only 2.1 billion years ago.
Differences between organisms and inanimate bodies
The term "living organism" implies the complex chemical composition of such an object. It contains proteins and nucleic acids. This is what distinguishes it from bodies. They also differ in the totality of their properties. Despite the fact that bodies of inanimate nature also have a number of physical and chemical properties, the concept of "organism" includes more numerous characteristics. They are much more varied.
To understand what is called an organism, it is necessary to study its properties. So it has the following characteristics:
Metabolism, which includes nutrition (consumption of useful substances), excretion (removal of harmful and unnecessary products), movement (change in the position of the body or its parts in space).
Perception and processing of information, which include irritability and excitability, allowing you to perceive external and internal signals and selectively respond to them.
Heredity, which allows you to transfer your traits to descendants and variability, which is the difference between individuals of the same species.
Development (irreversible changes throughout life), growth (increase in weight and size due to biosynthesis processes), reproduction (reproduction of others similar to themselves).
Classification based on cell structure
Specialists divide all forms of living organisms into 2 kingdoms:
Pre-nuclear (prokaryotes) - evolutionarily primary, the simplest type of cells. It was they who became the first forms of living organisms on Earth.
Nuclear (eukaryotes) derived from prokaryotes. This more advanced cell type has a nucleus. Most living organisms on our planet, including humans, are eukaryotic.
The nuclear kingdom, in turn, is divided into 4 kingdoms:
Protists (paraphyletic group), which are ancestral to all other living organisms;
Plants;
Animals.
Prokaryotes include:
Bacteria, including cyanobacteria (blue-green algae);
The characteristic features of these organisms are:
Lack of a formalized core;
The presence of flagella, vacuoles, plasmids;
The presence of structures in which photosynthesis takes place;
form of reproduction;
Ribosome size.
Despite the fact that all organisms differ in the number of cells and their specialization, all eukaryotes are characterized by a certain similarity in the structure of the cell. They differ in common origin, so this group is a monophyletic taxon of the highest rank. According to scientists, eukaryotic organisms appeared on earth about 2 million years ago. An important role in their appearance was played by symbiogenesis, which is a symbiosis between a cell that has a nucleus and is capable of phagocytosis, and the bacteria absorbed by it. It was they who became the precursors of such important organelles as chloroplasts and mitochondria.
Mesokaryotes
In nature, there are living organisms that are an intermediate link between prokaryotes and eukaryotes. They are called mesokaryotes. They differ from them in the organization of the genetic apparatus. This group of organisms includes dinoflagellates (dinophyte algae). They have a differentiated nucleus, but the cell structure retains the primitive features that are inherent in the nucleoid. The type of organization of the genetic apparatus of these organisms is considered not only as a transitional, but also as an independent branch of development.
Microorganisms
Microorganisms are called a group of living objects, extremely small in size. They cannot be seen with the naked eye. Most often, their size is less than 0.1 mm. This group includes:
Nuclear-free prokaryotes (archaea and bacteria);
Eukaryotes (protists, fungi).
The vast majority of microorganisms are a single cell. Despite this, there are unicellular organisms in nature that can be easily seen even without a microscope, for example, the giant polykaryon Thiomargarita namibiensis (marine gram-negative bacterium). Microbiology studies the life of such organisms.
transgenic organisms
Recently, such a phrase as a transgenic organism has been increasingly heard. What is it? It is an organism, into the genome of which the gene of another living object is artificially introduced. It is introduced in the form of a genetic construct, which is a DNA sequence. Most often it is a bacterial plasmid. Thanks to such manipulations, scientists obtain living organisms with qualitatively new properties. Their cells produce a gene protein that has been introduced into the genome.
The concept of "human body"
Like any other living objects, people are studied by the science of biology. The human body is a holistic, historically developed, dynamic system. It has a special structure and development. Moreover, the human body is in constant communication with the environment. Like all living objects on Earth, they form tissues:
Epithelial, located on the surface of the body. It forms the skin and lines the walls of hollow organs and blood vessels from the inside. Also, these tissues are present in closed body cavities. There are several types of epithelium: skin, kidney, intestinal, respiratory. The cells that form this tissue are the basis of such modified structures as nails, hair, and tooth enamel.
Muscular, with the properties of contractility and excitability. Thanks to this tissue, motor processes are carried out within the body itself and its movement in space. Muscles are made up of cells that contain microfibrils (contractile fibers). They are divided into smooth and striated muscles.
Connective, which includes bone, cartilage, adipose tissue, as well as blood, lymph, ligaments and tendons. All its varieties have a common mesodermal origin, although each of them has its own functions and structural features.
Nervous, which is formed by special cells - neurons (structural and functional unit) and neuroglia. They differ in their structure. So the neuron consists of a body and 2 processes: branching short dendrites and long axons. Covered with sheaths, they make up nerve fibers. Functionally, neurons are divided into motor (efferent), sensitive (afferent), intercalary. The place of transition from one of them to another is called a synapse. The main properties of this tissue are conductivity and excitability.
What is called the human body in a broader sense? Four types of tissues form organs (part of the body with a certain shape, structure and function) and their systems. How are they formed? Since one organ cannot cope with the performance of some functions, their complexes are formed. What are they? Such a system is a collection of several organs that have a similar structure, development and functions. All of them form the basis of the human body. These include the following systems:
Musculoskeletal (skeleton, muscles);
Digestive (glands and tract);
Respiratory (lungs, airways);
Sense organs (ears, eyes, nose, mouth, vestibular apparatus, skin);
Sexual (female and male genital organs);
Nervous (central, peripheral);
Circulatory (heart, blood vessels);
Endocrine (endocrine glands);
Integumentary (skin);
Urinary (kidneys, excretory tract).
The human body, the definition of which can be represented as a combination of various organs and their systems, has the main (determining) beginning - the genotype. It is the genetic constitution. In other words, it is a set of genes of a living object received from parents. Any kind of microorganisms, plants, animals has a characteristic genotype for it.
As you know, biology is a science that studies living organisms and their interaction in the natural environment.
But what is called an organism in biology, how to distinguish a living organism from inanimate matter, and what kind of organisms are there? Let's look into this issue.
What is an organism?
Word "organism" is of Latin origin and was used by medieval scholars. In Latin it sounds like "organismus" and is derived from the word "organizo", which is used in the meaning "arranging, organizing" . So in biology they call any living body that is able to exist separately from others and has a number of properties that distinguish it from inanimate objects. An organism is part of its species and its population, i.e. its appearance and characteristic features of life correspond to certain species qualities.
There are many types of living organisms on our planet. Their study and classification is within the scope of activities of biologists. The structural unit of any organism is a cell, i.e. they are all made up of different living cells responsible for different functions. Distinguish between unicellular and multicellular organisms:
— unicellular consist of a single cell and multiply mainly by division;
— multicellular consist of many cells of different types, and the process of reproduction in them is organized in various ways.
Classification of unicellular organisms
All single-celled, or simplest organisms that exist on our planet, are divided into two main groups:
- a group of prokaryotes, which includes unicellular organisms without a clearly defined cell nucleus and intracellular organelles, feeding on photosynthesis or chemosynthesis; 
- a group of eukaryotes, which includes unicellular organisms with well-formed cell nuclei and developed organelles.
It is believed that unicellular organisms arose before all other living beings and became the first organisms that appeared in the course of evolution.
What are multicellular organisms?
The structure of the vast majority of multicellular organisms includes different types of cells designed to perform various functions - nutrition, respiration, excretion of processed products, etc. At the same time, as studies have shown, in animal organisms there are multifunctional cells called stem cells. In plants, cambial cells have similar properties.
According to evolutionary theory, all multicellular organisms formed from groups or colonies of single-celled creatures. In the process of development, specialization arose and began to develop in the colony, when one group of cells performed mainly the function of absorbing oxygen, the other - the function of processing nutrients, the third was engaged in the removal of decay products. Over time, specialization deepened, and over millions of years of evolution, many types of highly developed living organisms were formed, consisting of millions of different cells.
What is the difference between a living organism and non-living matter?
At first glance, this is a very simple question, and it is very easy to distinguish a living being from non-living matter. But in order to formulate the difference and highlight the main features of a living being, scientists had to do a lot of work. Today it is recognized that a living organism has:
- metabolism, i.e. the ability to absorb substances from the environment, process and partially or completely incorporate them into oneself;
- perception and processing of information, i.e. the ability to respond to external stimuli by an arbitrary change in internal processes;
- the ability to reproduce, i.e. the ability to reproduce similar organisms; 
- development, i.e. the ability to change over time its appearance, size and internal structure.
All living organisms, from bacteria to humans, have these properties.
- (Late Lat. organismus from Late Lat. organizo I arrange, I give a slender appearance, from other Greek ὄργανον a tool) a living body that has a set of properties that distinguish it from inanimate matter. As a separate individual organism ... ... Wikipedia
- (new lat., from organum organ). A whole whose parts are inextricably linked; every living being that possesses organs for the maintenance and development of life in itself. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. ORGANISM ... ... Dictionary of foreign words of the Russian language
ORGANISM- ORGANISM, a set of interacting organs that form an animal or plant. The very word O. comes from the Greek organon, that is, a work, a tool. For the first time, apparently, Aristotle called living beings organisms, because according to him ... ... Big Medical Encyclopedia
- (from late Latin organizmo - I arrange, I report a slender appearance) a living being; covering a vast sphere of independent material unity, which in its structure is subject primarily to physical and chemical laws. In addition, the body as ... ... Philosophical Encyclopedia
ORGANISM, organism, husband. (from Greek organon tool) (book). 1. A living body that exists independently and consists of coordinated complex parts, organs. Animal body. plant organism. 2. The totality of individual ... Explanatory Dictionary of Ushakov
Cm … Synonym dictionary
ORGANISM- (from Latin organismus), in a broad sense, a biologically integral system consisting of interdependent and subordinate elements, the relationships and structural features of which are determined by their functioning as a whole; in a narrow sense, the body ... Ecological dictionary
organism- a, m. organisme m. 1. Every living being, a living body with its coordinated organs. ALS 1. An organ is an essential part of an organic, slender body or organism. 1840. Greek Readings 1 10. || Physical or... ... Historical Dictionary of Gallicisms of the Russian Language
organism- 1. A living organism is a living body, a living being (plant, animal, person). 2. The totality of the spiritual and physical properties of a person. 3. Complex organized unity. The words … Great Psychological Encyclopedia
- (French organisme, from cf. Lat. Organizo I arrange, I give a slender appearance), in the broadest, most general sense, living O. any biol. or a bio-inert holistic system, consisting of interdependent and subordinate elements, relationships to loose and ... ... Biological encyclopedic dictionary
A living being, a real carrier of life, characterized by all its properties. The body comes from a single germ. Individually subject to evolutionary and environmental impacts Glossary of business terms. Akademik.ru. 2001 ... Glossary of business terms
Books
- Organism and stress: stress of life and stress of death, Kitaev-Smyk Leonid Aleksandrovich. The study guide presents the results of research on emotional and bodily stress, conducted by the author over the years. Changes in emotions and behavior of different people are analyzed ...
A term that is often used in psychology (including this book) to describe a person or any animal. In a broader sense, it refers to all living beings, but the latter are not of immediate interest to psychologists. The term came into use after the publication of the first works in the field of behaviorism, where it indicated that all animals exhibit the same basic learning abilities, hence the discoveries made in the study of "lower" animals. can be extended to humans. Nowadays, the term is more often used to emphasize the objective attitude of the psychologist to the subject of research. Organisms are simply "living units" that react in a certain way to external and internal stimuli.
ORGANISM
Free meaning: any living being, be it plant or animal, bacterium or virus. This kind of definition is only somewhat satisfactory, since it is little more than a list of those units that are usually regarded as referring to organisms. Ideally, one should have a clear definition of what is meant by the term, and thus do without our list - and also avoid discussion of exactly which items deserve to be included in this list; not everyone would put viruses in it. The difficulty, however, is that attempts to deal with the definition of life are themselves lists; for example, a living being - one that performs some (or all) of the basic physiological functions of eating, excreting, reproducing, moving, etc. Since there is currently no agreed criteria set of properties to define what is living, there is no strict definition of what qualifies as an organism. In psychology, the term refers to an animal, especially one used in an experiment or other scientific study. This has proven to be a useful term for many behaviorists who, working primarily with rats, pigeons, and the like, preferred to formulate their results and conclusions with the implication that their findings could apply to all living things. Naturally, it is not surprising that one of the fundamental works of this tradition was the work of B.F. Skinner 1938 "The Behavior of Organisms
ORGANISM
from lat. organismus] - 1) living body, living being (human, animal, plant); 2) any biological or bioosseous integral system, consisting of interdependent and subordinate elements, the relationship of which is determined by their functioning as a whole; 3) the totality of the physical and spiritual properties of a person
organism
A separate living being, considered as an open self-regulating biological system, all parts of which are inextricably linked, supporting the exchange of matter and energy with the environment, capable of reproducing their own kind and of continuously adapting to environmental conditions.
organism
Greek organon - tool, tool) - 1. in general - any living creature, from a person to a virus. The brevity of this definition, formed according to the principle of Napoleon (“speak briefly and incomprehensibly”), alas, does not compensate for its significant shortcomings. The ambiguity of the definition is primarily due to the fact that a certain criteria set of properties has not yet been established that distinguishes a living being from inanimate objects, and clear sets of properties that distinguish one type of living being from another have not been established either. To eliminate this ambiguity, it would be nice to first determine what the essence of the processes of life is, but neither philosophers nor natural scientists are able to do this yet. Some thinkers hope that this will be helped by the tendency of scientific research to move to the atomic and subatomic level of organization of the structures of a living organism. So, J. Bernal points out: "Life is a partial, continuous, progressive, diverse and interacting with the environment self-realization of the potential possibilities of the electronic states of atoms." This is very similar to the illusion that the study of neurochemical processes and their self-realization in the brain sheds light on understanding the essence of consciousness. Secondly, any organism is an element of the biosphere, the boundaries of which remain undetermined, but it is quite clear that the manifestations of its vital activity cannot be comprehended outside the context of the latter. 2. in psychology, the designation of any animal that is used in an experiment or other scientific study. Scientists who take this position may also include viruses in the class of living organisms and not see any significant differences between a rat or a dog, on the one hand, and a person, on the other. In behaviorism, for example, experimental data obtained in experiments on a rat or a pigeon are freely transferred to other organisms, including humans. It does not seem surprising, therefore, that one of the foundational works in the behaviorist tradition was B.F. Skinner's The Behavior of Organisms (1938). Apparently, the day is not far off when, with this approach, android robots will also be ranked among living or even thinking beings; 2. in psychopathology - the general name of biological structures and processes in a person, a violation of which inevitably leads to the development of mental and personal pathology, but which, in turn, may also suffer due to socio-psychological dysfunction (for example, in conditions of inadequate or in a different way in society.
organism
from the late organizo, organizare - arrange, inform, slender appearance) - a complex morphologically and chemically organized system, the vital activity of which is ensured by the interaction of its cells, tissues and organs with various factors - internal and external. O. is constantly influenced by nutrients, the composition of the air, the bacterial environment, certain chemical reactions, the conditions of geographical location, etc. The peculiarity of O. is largely determined by its heredity, environment, and activities. It is characterized by constant metabolism, self-renewal, irritability and reactivity, self-regulation, movement, growth and development, heredity and variability, adaptability to the conditions of existence. The more complex O., the more it retains the constancy of the internal environment - homeostasis (body temperature, biochemical composition of blood, etc.), regardless of external influences, acquires socio-economic features. Due to the variability of the moments that dictate the conditions for the existence of O., each person always differs from others in structure and functions. Thus, there is individual variability of the physical type, but at the same time there are also age-related changes (from early embryonic development to old age inclusive) and the phenomena of sexual demorphism. The morphology of O. includes: 1) merology (from the Greek "meros" - part), which studies both the variations of individual organs and tissues and their connections, and 2) somatology (from the Greek "soma" - body), when the body is studied in general, variations of its height, mass, proportions, etc. Literally translated from Latin, "catfish" is equivalent to the Russian "body" and the limb apparatus fixed on it. In ancient times, for the Greeks, the understanding of personality was inseparable from a well-organized living body, and to some extent identical to it. However, historically, "soma" and "body" are not all equivalent. In biology, the body is most often understood as an organism that combines both the soma, which has a certain length, size, surface and relief, and the viscera (i.e., internal organs that are divided into systems: digestive, respiratory, urinary, sexual, endocrine glands ; in addition, they secrete pathways that conduct fluids and irritation). When using the adjective somatic, as a rule, bodily properties are implied, which are clearly different from mental phenomena. In particular, bones, joints and ligaments, muscles are recognized as elements of soma. Already unicellular organisms (prokaryotes) have a set of basic vital properties that provide them with the opportunity to live, to carry out various integral phenomena (metabolic processes, movement, adaptability, etc.). All these are the signs that distinguish O. from inanimate nature. Eukaryotes are multicellular organisms. They also have a body differentiated into various tissues, and represent an integral system, a kind of "cellular state", sensitively interacting with the external environment. Four types of tissues are distinguished in human O.: (1) epithelial tissues (from the Greek epi - a protrusion on the body; the term was introduced in 1708 by the anatomist Ruisch), cover the surface of the body, line the mucous membranes, separating the body from the environment (integumentary epithelium ) and form glands (glandular epithelium); There are also sensory epithelium, the modified cells of which perceive specific stimuli in the organs of hearing, balance and taste. The epithelium is characterized by an abundance of cellular elements; (2) connective tissues, formed from numerous cells, are a vast group. It includes loose and dense fibrous tissues, as well as tissues with special properties (reticular, pigment, fatty), solid skeletal (bone, cartilage) and liquid (blood and lymph). Connective tissue performs supporting, mechanical (dense, fibrous connective tissue, cartilage, bone), trophic (nutritional) and protective (phagocytosis and antibody production) functions; (3) muscle tissue that carries out movement and is able to contract. There are two varieties of it: smooth (non-striated) and striated (skeletal and cardiac); (4) nervous tissue forms the central nervous system (brain and spinal cord) and peripheral (nerves with their terminal devices, nerve ganglions). It consists of nerve cells (neurons) and neuroglia, which is created by gliocytes. Systematic anatomy groups all body tissues into systems: I) the doctrine of bones - osteologia (osteon - bone, logos - word, doctrine); 2) the doctrine of ligaments and joints - syndesmologia, arthrologia (syn - together, desmao - I connect; arthron - joint); 3) the doctrine of muscles - myologia (mus - muscle); 4) the doctrine of the insides - splanchnologia (splanchna - insides); 5) the doctrine of vessels - angiologia (angion - vessel); 6) the doctrine of the nervous system - neurologia (neuron - nerve); 7) the doctrine of the sense organs - esthesiologia (Greek aisthesis - feeling). V. Dahl pointed out that the word "organism" comes from the word "organ" ("tool"). In this regard, there was an idea that an organ (liver, heart, uterus, etc.) is a separate part of an integral organism that performs certain specific functions. Every organ has its own shape and structure. Each organ has characteristic features. 1) Topographic - the location of the organ in certain body cavities: chest, abdominal, pelvic (some organs are taken out of these cavities: the larynx on the neck, testicles - in the scrotum). 2) Genetic - the development of various organs from a single system (for example, the kidneys and sex glands). 3) Functional - inseparable functional cooperation of the digestive, respiratory and excretory systems. Violation of functions in one of the systems inevitably causes a reaction in other systems of the body. Each organ consists of one (bone) or several (stomach, kidneys, uterus, etc.) tissues, that is, it combines various elements and performs specific functions. The elements of any organ are cells, intercellular substance, tissues, lymphoid formations, blood and lymphatic vessels, and nerves. Usually, an organ is represented by a skeleton - stroma (consists of connective tissue) and parenchyma - a specific tissue of the organ (epithelium in the glands, muscle tissue in the muscles), as well as the vascular and nervous systems. Homologous organs are also distinguished - originating from the same rudiments, and similar - similar in function. There are also rudimentary (Latin rudimentum - germ) organs that have not received full development in humans (tail rudiment, mammary glands in men, muscles of the auricle, gill slits, etc.). The organs, as it were, complement each other functionally: the mouth - the pharynx - the esophagus - the stomach - the small and only then the large intestine. Others do not have a direct anatomical connection (for example, the endocrine system). There are parenchymal (Greek par?nthyma - "pouring near", meaning a specific tissue) organs: liver, kidneys, and hollow: uterus, ureters, pharynx. Organs are located in body cavities. Each of them is laid at a strictly defined time, has specific stages of growth, the time of maximum functioning and decay. For precise orientation of organs, the following additional criteria are used: skeletopy - the ratio of an organ to a specific area of the skeleton; syntopy - the ratio of organs to each other; holotopy - projection of the organ on the outer integument and on the walls of the cavities within the established topographic anatomical areas. When evaluating the shape, size, structure and topography of organs, gender, constitutional, age and individual differences are taken into account. The human body is also subject to bilateral symmetry, which is regarded as a universal feature of vertebrates. But such symmetry takes place when evaluating the skeleton and muscular system, and the stomach, intestines, heart, liver, spleen and other organs are located asymmetrically. This is considered as a secondary phenomenon, as a result of the movements of organs in the process of their development.
