Signs

Sarcodaceae

(common amoeba)

Flagellates

(green euglena)

Ciliates

(ciliate slipper)

Body structure

A unicellular microscopic animal 0.1-0.5 mm, living in water. It moves with the help of temporary outgrowths of the cytoplasm - pseudopodia (false legs); covered cell membrane, cytoplasm has all organelles, nucleus, vacuoles

A single-celled microscopic animal 0.05 mm in size that lives in water. At the anterior end of the fusiform body there is one flagellum, a light-sensitive ocellus and a contractile vacuole. The cell organelles are the same as those of the amoeba, in addition, there are organelles containing chlorophyll - chromatophores

A unicellular microscopic animal 0.1-0.3 mm, living in water. The cell membrane is dense, with rows of cilia. Shoe-shaped. Cytoplasm with organelles, there are a large (macronucleus) and a small (micronucleus) nuclei, two contractile vacuoles, and digestive vacuoles. On the lateral side there is a perioral funnel and powder

Bacteria, unicellular algae. Due to phagocytosis, a digestive vacuole is formed. Solutes are digested, solids are released anywhere in the cell

In the light, nutrition is autotrophic (photosynthesis), like in plants. In the absence of light for a long time, nutrition becomes heterotrophic, saprotrophic. Digestive vacuole does not form

It feeds on bacteria, which are driven into the mouth by cilia through the perioral funnel (cystoma), enter the pharynx, and then into the cytoplasm, where a digestive vacuole is formed. Undigested particles are removed through the powder

Gas exchange occurs through the outer cell membrane. Respiratory and energy center mitochondria serve

Like an amoeba

Like an amoeba

Selection

Water and waste products are collected in a contractile vacuole and carried out

Like an amoeba

Water and waste products are collected into two contractile vacuoles with afferent tubules

Reaction to irritation

Positive taxis for food, light, negative taxis for salt

Like an amoeba

Sexual process

Absent

Absent

Conjugation

Reproduction

It occurs as a result of cell division in two through mitosis. DNA molecule doubles in interphase

It is carried out due to cell division through mitosis along the cell axis. DNA molecule doubles in interphase

It is carried out as a result of mitotic cell division in two across the cell axis. DNA molecule doubles in interphase

Meaning

Positive: a component of the biocenosis in the food chain, sea rhizomes have a calcareous shell - they form sedimentary rocks - chalk, limestone; Some types of rhizomes indicate the presence of oil. Negative: dysenteric amoeba causes an infectious disease

Positive: component of biocenosis in the food chain; has educational significance for the study of the common ancestors of plants and animals. Negative: causes algae in water bodies; parasitic flagellates settle in the blood, intestines of animals and humans, causing diseases

Other representatives

Difflugia, arcella, euglypha, foraminifera, radiolaria acantharia, sunflower, globigerina

Volvox, Trichomonas, Giardia, Leishmania, Trypanosomes

Summarizing tables on the topic “Evolution of organ systems”

I am working on the V.V. program. Beekeeper. In the course “Animals” there appeared, in my opinion, a very interesting, but also very difficult for students chapter “Evolution” various systems" O.A. Pepelyaev and I.V. Suntsova in her manual “Lesson developments in biology. 7th–8th grade” propose giving children tables that they must fill out on their own. It also seems to me that with tables it is much easier to systematize and remember this material. But it is difficult for students to accurately and competently fill out such a table on their own. Sometimes the guys and I do this together, and sometimes I give the students ready-made tables and we analyze this material while reading the textbook.

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Table “Evolution of excretory organs”

Conclusion

The evolution of the excretory system went towards the creation of specialized organs that ensure the removal from the body of dangerous and sometimes simply toxic substances formed in the process of life.

Table "Evolution of the respiratory system"

Conclusion

The evolution of the respiratory organs in vertebrates followed the path:

– increasing the area of ​​the pulmonary septa;
– improving transport systems for oxygen delivery to cells located inside the body.

Table "Body coverings"

Conclusion

The evolution of body coverings followed the path:

– increasing the number of layers;
– the appearance of new formations: cilia, glands, calcareous and chitinous covers, scales, claws, feathers, hair, horns, hooves, etc.

Photo from the site: http://aqua-room.com

The subkingdom Protozoa includes animals whose body consists of a single cell. This cell performs all the functions of a living organism: it moves independently, feeds, processes food, breathes, removes unnecessary substances from its body, and reproduces. Thus, protozoa combine the functions of a cell and an independent organism (in multicellular animals these tasks are performed various groups cells combined into tissues and organs).

Among protozoa there are animals in which individuals of daughter generations, during asexual reproduction, remain united with the maternal organisms into a single colony

Currently, about 70 thousand species of protozoa are known, most of which are single-celled organisms, usually microscopic in size. In 1675, thanks to the invention of the microscope, the Dutch scientist Antonie van Leeuwenhoek was able to study single-celled organisms. The usual sizes of protozoa are 20-50 microns (microns), and the smallest of them reach only 2-4 microns. And only some ciliates are visible to the naked eye, since their length sometimes reaches S mm. And the body diameter of individual representatives of extinct single-celled foraminifera was hundreds and thousands of times larger.

Protozoa live only in a liquid environment - in the water of various bodies of water - from seas to droplets on moss “pillows” of swamps, in moist soil, inside plants and animals.

Habitat and external structure. Amoeba proteus, or ordinary amoeba, lives at the bottom of small fresh water bodies: in ponds, old puddles, ditches with stagnant water. Its value does not exceed 0.5 mm. Amoeba does not have proteus permanent shape body, as it lacks a dense shell. Its body forms outgrowths - pseudopods. With their help, the amoeba moves slowly - “flows” from one place to another, crawls along the bottom, and captures prey. For such variability in body shape, the amoeba was given the name of the ancient Greek deity Proteus, who could change his appearance. Externally, amoeba proteus resembles a small gelatinous lump. An independent single-celled organism, the amoeba contains cytoplasm covered with a cell membrane. Outer layer The cytoplasm is transparent and denser. Its inner layer is granular and more fluid. The cytoplasm contains the nucleus and vacuoles - digestive and contractile

Movement. Moving, the amoeba seems to slowly flow along the bottom. First, a protrusion appears in some place of the body - a pseudopod.

It is fixed at the bottom, and then the cytoplasm slowly moves into it. By releasing pseudopods in a certain direction, the amoeba crawls at a speed of up to 0.2 mm per minute.

Nutrition. Amoeba feeds on bacteria, single-celled animals and algae, small organic particles - the remains of dead animals and plants. When it encounters prey, the amoeba grabs it with its pseudopods and envelops it from all sides (see Fig. 21). A digestive vacuole is formed around this prey, in which the food is digested and from which it is absorbed into the cytoplasm. After this happens, the digestive vacuole moves to the surface of any part of the amoeba’s body and the undigested contents of the vacuole are thrown out. To digest food with the help of one vacuole, the amoeba requires from 12 hours to 5 days.

Selection. In the cytoplasm of the amoeba there is one contractile (or pulsating) vacuole. It periodically collects soluble harmful substances that are formed in the body of the amoeba in the process of life. Once every few minutes this vacuole fills and, having reached its maximum size, approaches the surface of the body. The contents of the contractile vacuole are pushed out. Except harmful substances the contractile vacuole removes excess water from the amoeba's body, which comes from the environment. Since the concentration of salts and organic substances in the amoeba’s body is higher than in the environment, water constantly enters the body, so without its release the amoeba could burst.

Breath. The amoeba breathes oxygen dissolved in water, which penetrates the cell: gas exchange occurs through the entire surface of the body. The complex organic substances of the amoeba's body are oxidized by incoming oxygen. As a result, the energy necessary for the life of the amoeba is released. This produces water, carbon dioxide and some other chemical compounds which are removed from the body.

Reproduction. Amoebas reproduce asexually - by dividing the cell in two. During asexual reproduction, the amoeba nucleus is first divided in half. Then a constriction appears on the body of the amoeba. It divides it into two almost equal parts, each of which contains a core. Under favorable conditions, the amoeba divides approximately once a day.

Class Mammals. general characteristics class. External structure. Skeleton and musculature. Body cavity. Organ system. Nervous system and sensory organs. Behavior. Reproduction and development. Caring for offspring.

The body of mammals has the same sections as other terrestrial vertebrates: head, neck, torso, tail and two pairs of limbs. The limbs have sections typical of vertebrates: shoulder (thigh), forearm (lower leg) and hand (foot). The legs are not located on the sides, as in amphibians and reptiles, but under the body. Therefore, the body is raised above the ground. This expands the possibilities of using limbs. Among the animals, tree-climbing, plantigrade and digitally walking animals, jumping and flying are known. In the structure of the head, the facial and cranial sections are clearly distinguishable (Fig. 191). In front is the mouth, surrounded by soft lips. At the end of the muzzle there is a nose covered with bare skin with a pair of nasal openings. On the front sides of the head are the eyes, protected by movable eyelids, along the outer edges of which there are long eyelashes. Well developed lacrimal glands, the secretion of which washes the eyes and has a bactericidal effect. Closer to the back of the head, above the eyes, on the sides of the head there are large ears, which turn towards the sound source and allow you to directionally capture it. In wool, there are more rigid and long guard hairs and short soft hairs that form the undercoat. Long, stiff hairs located on the muzzle and performing a tactile function are called vibrissae. Animals shed periodically according to the seasons: the thickness and color of their fur changes. In winter, the fur is thicker, and in animals living on snow cover it becomes white. In summer, the coat is thinner and colored in protective dark tones. Musculoskeletal system. The skeleton of mammals consists of the same sections as those of other terrestrial vertebrates: the skull, spine, trunk skeletons, girdles and free limbs. Mammalian bones are strong and many are fused together. The skull is large and consists of fewer bones than in reptiles, since many fuse together in the embryonic period. The jaws are strong, armed with teeth, which are located in recesses - alveoli.

The spine consists of the following five sections: cervical (seven vertebrae), thoracic (twelve vertebrae), lumbar (six to seven vertebrae), sacral (four fused vertebrae) and caudal section of different numbers vertebrae in different mammals. The vertebrae are massive, with flattened surfaces of their bodies. The ribs are attached to the thoracic vertebrae, some of them are connected to the sternum, forming the rib cage. The forelimb girdle consists of paired clavicles and paired shoulder blades. The barkoids (crow bones) are reduced in most animals. In horses and dogs, whose legs move only along longitudinal axis bodies, reduced and clavicles. The hind limb girdle (pelvic girdle) consists of two large pelvic bones. Each of them arose from the fusion of the pubic, ischial and ilium bones. The pelvic bones fuse with the sacrum.

In mammals a complex system muscles. The muscles that move the limbs are the most developed. They begin on the bones of the girdles and attach to the bones of the free limb. Long tendons connect to the bones of the foot and hand, which ensures good mobility of the limbs, expanding their adaptive capabilities.

The intercostal respiratory muscles are well developed, the contraction of which raises and lowers the chest. There are muscles that connect to the skin: for example facial muscles, the contraction of which causes twitching of the skin, movement of the coat, and whiskers.

In all mammals, the thoracic cavity is separated from the abdominal cavity by a muscular septum - the diaphragm. It enters the chest cavity with a wide dome and is adjacent to the lungs.

Protozoa do not have special respiratory organelles; they absorb oxygen and release carbon dioxide over the entire surface of the body.

Like all living beings, protozoa have irritability, that is, the ability to respond in one way or another to factors acting from the outside.

Protozoa react to mechanical, chemical, thermal, light, electrical and other stimuli. The reactions of protozoa to external stimuli are often expressed in a change in the direction of movement and are called taxis.

Taxis can be positive if the movement is in the direction of the stimulus, and negative if it is in the opposite direction.

The reactions of multicellular animals to stimuli are carried out under the influence of the nervous system. Many researchers have tried to discover analogues of the nervous system in protozoa (i.e., within the cell). American scientists, for example, described many ciliates as having a special nerve center(the so-called motorium), which is a special compacted area of ​​the cytoplasm. From this center a system of thin fibers, which were considered as conductors of nerve impulses, extends to various parts of the body of the pnfusoria.

Other researchers, using special methods of silvering preparations (treatment with silver nitrate followed by reduction of metallic silver), discovered a network of the finest fibers in the ectoplasm of ciliates. These structures (Fig.) were also considered as nerve elements through which the excitation wave propagates. At present, however, most scientists studying fine fibrillar structures have a different opinion about their functional role in the protozoan cell. No experimental evidence has been obtained for the neural role of fibrillar structures. On the contrary, there is experimental data that makes it possible to assume that in protozoa the wave of excitation propagates directly through the outer layer of the cytoplasm - the ectoplasm. As for various kinds fibrillar structures, which until recently were considered as the “nervous system” of protozoa, then they most likely have a supporting (skeletal) significance and contribute to the preservation of the shape of the protozoan’s bodies.

All life on Earth exists thanks to solar heat and energy reaching the surface of our planet. All animals and humans have adapted to extract energy from organic substances synthesized by plants. To use the solar energy contained in the molecules of organic substances, it must be released by oxidizing these substances. Most often, air oxygen is used as an oxidizing agent, since it makes up almost a quarter of the volume of the surrounding atmosphere.

Single-celled protozoa, coelenterates, free-living flatworms and roundworms breathe the entire surface of the body. Special respiratory organs - feathery gills appear in marine annelids and aquatic arthropods. The respiratory organs of arthropods are trachea, gills, leaf-shaped lungs located in the recesses of the body cover. The respiratory system of the lancelet is presented gill slits piercing the wall of the anterior intestine - the pharynx.

Structure and functions of the respiratory organs

A necessary condition for the life of the body is constant gas exchange between the body and environment. The organs through which inhaled and exhaled air circulate are combined into a breathing apparatus. The respiratory system consists of the nasal cavity, pharynx, larynx, trachea, bronchi and lungs. Most of them are airways and serve to conduct air into the lungs. Gas exchange processes take place in the lungs. When breathing, the body receives oxygen from the air, which is carried by the blood throughout the body. Oxygen participates in complex oxidative processes of organic substances, during which it is released necessary for the body energy. The final products of decomposition - carbon dioxide and partially water - are removed from the body into the environment through the respiratory system.

Functions of the respiratory system

• Providing the body cells with oxygen O 2.
• Removing carbon dioxide CO 2 from the body, as well as some end products of metabolism (water vapor, ammonia, hydrogen sulfide).

Nasal cavity

The airways begin with nasal cavity, which connects with the environment through the nostrils. From the nostrils, air passes through the nasal passages, which are lined with mucous, ciliated and sensitive epithelium. The external nose consists of bone and cartilage formations and has the shape of an irregular pyramid, which varies depending on the structural features of the person. The bony skeleton of the external nose includes the nasal bones and the nasal part of the frontal bone.

The turbinates are located on the side walls of the nasal cavity - three on each side, which increases the inner surface of the nose with which the inhaled air comes into contact.

Nasal cavity formed by two narrow and winding nasal passages. Here the air is warmed, humidified and freed from dust particles and microbes. The membrane lining the nasal passages consists of cells that secrete mucus and ciliated epithelial cells. By the movement of the cilia, mucus, along with dust and germs, is directed out of the nasal passages.

The inner surface of the nasal passages is richly supplied with blood vessels. The inhaled air enters the nasal cavity, is heated, humidified, cleaned of dust and partially neutralized. From the nasal cavity it enters the nasopharynx. Then air from the nasal cavity enters the pharynx, and from it into the larynx.

Larynx

Larynx- one of the sections of the airways. Air enters here from the nasal passages through the pharynx. There are several cartilages in the wall of the larynx: thyroid, arytenoid, etc. At the moment of swallowing food, the neck muscles raise the larynx, and the epiglottic cartilage lowers and closes the larynx. Therefore, food only enters the esophagus and does not enter the trachea.

Located in the narrow part of the larynx vocal cords, in the middle between them there is a glottis. As air passes through, the vocal cords vibrate, producing sound. The formation of sound occurs during exhalation with human-controlled air movement. The formation of speech involves: the nasal cavity, lips, tongue, soft palate, facial muscles.

Trachea

The larynx goes into trachea (windpipe), which has the shape of a tube about 12 cm long, in the walls of which there are cartilaginous half-rings that do not allow it to fall off. Its posterior wall is formed by a connective tissue membrane. The cavity of the trachea, like the cavity of other airways, is lined with ciliated epithelium, which prevents the penetration of dust and other substances into the lungs. foreign bodies. The trachea occupies a middle position, at the back it is adjacent to the esophagus, and on the sides of it there are neurovascular bundles. Front cervical region the trachea covers the muscles, and at the top it is also covered thyroid gland. Thoracic region trachea is covered in front by the manubrium of the sternum, the remains thymus gland and vessels. The inside of the trachea is covered with a mucous membrane containing a large amount of lymphoid tissue and mucous glands. When breathing, small particles of dust stick to the moist mucous membrane of the trachea, and the cilia ciliated epithelium promote them back to the exit from the respiratory tract.

The lower end of the trachea is divided into two bronchi, which then branch repeatedly and enter the right and left lungs, forming a “bronchial tree” in the lungs.

Bronchi

In the chest cavity, the trachea divides into two bronchus- left and right. Each bronchus enters the lung and there is divided into bronchi of smaller diameter, which branch into the smallest air tubes - bronchioles. Bronchioles, as a result of further branching, transform into extensions - alveolar ducts, on the walls of which there are microscopic protrusions called pulmonary vesicles, or alveoli.

The walls of the alveoli are built from a special thin single-layer epithelium and are densely intertwined with capillaries. The total thickness of the alveolar wall and the capillary wall is 0.004 mm. Gas exchange occurs through this thinnest wall: oxygen enters the blood from the alveoli, and carbon dioxide enters back. There are several hundred million alveoli in the lungs. Their total surface in an adult is 60–150 m2. Thanks to this, a sufficient amount of oxygen enters the blood (up to 500 liters per day).

Lungs

Lungs occupy almost the entire cavity of the thoracic cavity and are elastic, spongy organs.

There are three surfaces on the lung: the outer, or costal, the medial, facing the other lung, and the lower, or diaphragmatic. In addition, in each lung there are two edges: anterior and inferior, separating the diaphragmatic and medial surfaces from the costal surface. At the back, the costal surface, without a sharp border, passes into the medial surface. The anterior edge of the left lung has a cardiac notch. The hilum is located on the medial surface of the lung. The gateway of each lung includes the main bronchus, the pulmonary artery, which carries venous blood to the lung, and the nerves that innervate the lung. Two pulmonary veins emerge from the gates of each lung, which carry arterial blood and lymphatic vessels to the heart.

The lungs have deep grooves dividing them into lobes - upper, middle and lower, and in the left there are two - upper and lower. The lung sizes are not the same. The right lung is slightly larger than the left, while it is shorter and wider, which corresponds to the higher position of the right dome of the diaphragm due to the right-sided location of the liver. Color of normal lungs childhood pale pink, and in adults they acquire a dark gray color with a bluish tint - a consequence of the deposition of dust particles that enter them with the air. Lung tissue is soft, delicate and porous.

Gas exchange of the lungs

There are three main phases in the complex process of gas exchange: external breathing, gas transfer by blood and internal, or tissue, respiration. External respiration combines all processes occurring in the lung. It is carried out by the respiratory apparatus, which includes the chest with the muscles that move it, the diaphragm and the lungs with the airways.

The air entering the lungs during inhalation changes its composition. The air in the lungs gives up some of the oxygen and is enriched with carbon dioxide. The carbon dioxide content in venous blood is higher than in the air in the alveoli. Therefore, carbon dioxide leaves the blood into the alveoli and its content is less than in the air. First, oxygen dissolves in the blood plasma, then binds to hemoglobin, and new portions of oxygen enter the plasma.

The transition of oxygen and carbon dioxide from one environment to another occurs due to diffusion from higher to lower concentrations. Although diffusion is slow, the surface of contact between blood and air in the lungs is so large that it completely ensures the necessary gas exchange. It is estimated that complete gas exchange between blood and alveolar air can occur in a time that is three times shorter than the time the blood remains in the capillaries (i.e., the body has significant reserves of providing tissues with oxygen).

Venous blood, once in the lungs, gives off carbon dioxide, is enriched with oxygen and turns into arterial blood. In a large circle, this blood disperses through the capillaries to all tissues and gives oxygen to the cells of the body, which constantly consume it. There is more carbon dioxide released by cells as a result of their vital activity than in the blood, and it diffuses from the tissues into the blood. Thus, arterial blood, having passed through the capillaries of the systemic circulation, becomes venous and the right half of the heart is sent to the lungs, here it is again saturated with oxygen and gives off carbon dioxide.

In the body, breathing is carried out using additional mechanisms. Liquid media that make up blood (its plasma) have low solubility of gases in them. Therefore, in order for a person to exist, he would need to have a heart 25 times more powerful, lungs 20 times more powerful, and pump more than 100 liters of fluid (not five liters of blood) in one minute. Nature has found a way to overcome this difficulty by adapting a special substance - hemoglobin - to carry oxygen. Thanks to hemoglobin, blood is able to bind oxygen 70 times, and carbon dioxide - 20 times more than the liquid part of the blood - its plasma.

Alveolus- a thin-walled bubble with a diameter of 0.2 mm filled with air. The alveolar wall is formed by a single layer of squamous epithelial cells, outer surface of which a network of capillaries branches. Thus, gas exchange occurs through a very thin septum formed by two layers of cells: the capillary wall and the alveolar wall.

Exchange of gases in tissues (tissue respiration)

The exchange of gases in tissues occurs in capillaries according to the same principle as in the lungs. Oxygen from tissue capillaries, where its concentration is high, goes into tissue fluid with lower oxygen concentration. From the tissue fluid it penetrates into the cells and immediately enters into oxidation reactions, so there is practically no free oxygen in the cells.

Carbon dioxide, according to the same laws, comes from cells, through tissue fluid, into capillaries. The released carbon dioxide promotes the dissociation of oxyhemoglobin and itself combines with hemoglobin, forming carboxyhemoglobin, is transported into the lungs and released into the atmosphere. In the venous blood flowing from the organs, carbon dioxide is found both in a bound and dissolved state in the form of carbonic acid, which easily breaks down into water and carbon dioxide in the capillaries of the lungs. Carbonic acid can also combine with plasma salts to form bicarbonates.

In the lungs, where venous blood enters, oxygen saturates the blood again, and carbon dioxide moves from a zone of high concentration (pulmonary capillaries) to a zone of low concentration (alveoli). For normal gas exchange, the air in the lungs is constantly replaced, which is achieved by rhythmic attacks of inhalation and exhalation, due to the movements of the intercostal muscles and the diaphragm.

Transport of oxygen in the body

The meaning of breathing.

Breath- is a set of physiological processes that ensure gas exchange between the body and the external environment ( external breathing), and oxidative processes in cells, as a result of which energy is released ( internal breathing). Exchange of gases between blood and atmospheric air (gas exchange) - carried out by the respiratory system.

The source of energy in the body is food substances. The main process that releases the energy of these substances is the process of oxidation. It is accompanied by the binding of oxygen and the formation of carbon dioxide. Considering that the human body has no reserves of oxygen, its continuous supply is vital. Stopping the access of oxygen to the body's cells leads to their death. On the other hand, carbon dioxide formed during the oxidation of substances must be removed from the body, since the accumulation of a significant amount of it is life-threatening. The absorption of oxygen from the air and the release of carbon dioxide occurs through the respiratory system.

The biological significance of breathing is:

• providing the body with oxygen;
• removing carbon dioxide from the body;
• oxidation organic compounds BZHU with the release of energy necessary for human life;
• removal of metabolic end products ( water vapor, ammonia, hydrogen sulfide, etc.).

Source: biouroki.ru

Introduction

The respiratory system is a set of organs whose purpose is to provide the human body with oxygen. The process of providing oxygen is called gas exchange. Oxygen inhaled by a person is converted into carbon dioxide when exhaled. Gas exchange occurs in the lungs, namely in the alveoli. Their ventilation is realized by alternating cycles of inhalation (inspiration) and exhalation (expiration). The process of inhalation is interconnected with physical activity diaphragm and external intercostal muscles. As you inhale, the diaphragm lowers and the ribs rise. The exhalation process occurs mostly passively, involving only the internal intercostal muscles. As you exhale, the diaphragm rises and the ribs fall.

Breathing is usually divided according to the method of expansion of the chest into two types: thoracic and abdominal. The first is more often observed in women (the expansion of the sternum occurs due to the elevation of the ribs). The second is more often observed in men (the expansion of the sternum occurs due to deformation of the diaphragm).

The structure of the respiratory system

The respiratory tract is divided into upper and lower. This division is purely symbolic and the boundary between the upper and the lower paths breathing takes place at the intersection of the respiratory and digestive systems at the top of the larynx. The upper respiratory tract includes the nasal cavity, nasopharynx and oropharynx with the oral cavity, but only partially, since the latter is not involved in the breathing process. The lower respiratory tract includes the larynx (although sometimes it is also referred to as upper paths), trachea, bronchi and lungs. The airways inside the lungs are like a tree and branch approximately 23 times before oxygen reaches the alveoli, where gas exchange occurs. You can see a schematic representation of the human respiratory system in the figure below.

Structure of the human respiratory system: 1- Frontal sinus; 2- Sphenoid sinus; 3- Nasal cavity; 4- Nasal vestibule; 5- Oral cavity; 6- Pharynx; 7- Epiglottis; 8- Vocal fold; 9- Thyroid cartilage; 10- Cricoid cartilage; 11- Trachea; 12- Apex of the lung; 13- Upper lobe (lobar bronchi: 13.1- Right upper; 13.2- Right middle; 13.3- Right lower); 14- Horizontal slot; 15- Oblique slot; 16- Middle beat; 17- Lower lobe; 18- Aperture; 19- Upper lobe; 20- Lingular bronchus; 21- Carina of trachea; 22- Intermediate bronchus; 23- Left and right main bronchi (lobar bronchi: 23.1- Left upper; 23.2- Left lower); 24- Oblique slot; 25- Heart tenderloin; 26- Luvula of the left lung; 27- Lower lobe.

The respiratory tract acts as a link between the environment and the main organ of the respiratory system - the lungs. They are located inside the chest and are surrounded by the ribs and intercostal muscles. Directly in the lungs, the process of gas exchange occurs between oxygen supplied to the pulmonary alveoli (see figure below) and the blood that circulates inside the pulmonary capillaries. The latter deliver oxygen to the body and remove gaseous metabolic products from it. The ratio of oxygen and carbon dioxide in the lungs is maintained at a relatively constant level. Stopping the supply of oxygen to the body leads to loss of consciousness ( clinical death), then to irreversible disorders of brain function and ultimately to death (biological death).

Structure of the alveoli: 1- Capillary bed; 2- Connective tissue; 3- Alveolar sacs; 4- Alveolar duct; 5- Mucous gland; 6- Mucous lining; 7- Pulmonary artery; 8- Pulmonary vein; 9- Opening of the bronchiole; 10- Alveolus.

The breathing process, as I said above, is carried out due to the deformation of the chest with the help of respiratory muscles. Breathing itself is one of the few processes occurring in the body that is controlled by it both consciously and unconsciously. This is why a person during sleep, being in unconscious continues to breathe.

Functions of the respiratory system

The main two functions that the human respiratory system performs are breathing itself and gas exchange. Among other things, it is involved in such equally important functions as maintaining the thermal balance of the body, forming the timbre of the voice, smell perception, and also increasing the humidity of inhaled air. Lung tissue takes part in the production of hormones, water-salt and lipid metabolism. In the extensive vascular system of the lungs, blood is deposited (stored). The respiratory system also protects the body from mechanical environmental factors. However, of all this variety of functions, we will be interested in gas exchange, since without it neither metabolism, nor the formation of energy, nor, as a consequence, life itself would occur.

During breathing, oxygen enters the blood through the alveoli, and carbon dioxide is removed from the body through them. This process involves the penetration of oxygen and carbon dioxide through the capillary membrane of the alveoli. At rest, the oxygen pressure in the alveoli is approximately 60 mmHg. Art. higher than the pressure in blood capillaries lungs. Due to this, oxygen penetrates into the blood, which flows through the pulmonary capillaries. In the same way, carbon dioxide penetrates in the opposite direction. The gas exchange process occurs so quickly that it can be called virtually instantaneous. This process is shown schematically in the figure below.

Scheme of the gas exchange process in the alveoli: 1- Capillary network; 2- Alveolar sacs; 3- Opening of the bronchiole. I- Oxygen supply; II- Removal of carbon dioxide.

We've sorted out gas exchange, now let's talk about the basic concepts regarding breathing. The volume of air inhaled and exhaled by a person in one minute is called minute breathing volume. It provides required level gas concentrations in the alveoli. The concentration indicator is determined tidal volume is the amount of air that a person inhales and exhales during breathing. And frequency breathing movements , in other words – breathing frequency. Inspiratory reserve volume- This is the maximum volume of air that a person can inhale after a normal breath. Hence, expiratory reserve volume- this is the maximum amount of air that a person can exhale additionally after a normal exhalation. The maximum volume of air that a person can exhale after a maximum inhalation is called vital capacity lungs. However, even after maximum exhalation, a certain amount of air remains in the lungs, which is called residual lung volume. The sum of vital capacity and residual lung volume gives us total lung capacity, which in an adult is equal to 3-4 liters of air per lung.

The moment of inhalation brings oxygen to the alveoli. In addition to the alveoli, air also fills all other parts of the respiratory tract - the oral cavity, nasopharynx, trachea, bronchi and bronchioles. Since these parts of the respiratory system are not involved in the process of gas exchange, they are called anatomically dead space. The volume of air that fills this space is healthy person, as a rule, is about 150 ml. With age, this figure tends to increase. Since at the moment of deep inspiration the airways tend to expand, it must be borne in mind that the increase in tidal volume is simultaneously accompanied by an increase in the anatomical dead space. This relative increase in tidal volume usually exceeds that of the anatomical dead space. As a result, as tidal volume increases, the proportion of anatomical dead space decreases. Thus, we can conclude that an increase in tidal volume (during deep breathing) provides significantly better ventilation of the lungs, compared to rapid breathing.

Breathing regulation

To fully provide the body with oxygen, the nervous system regulates the rate of ventilation of the lungs by changing the frequency and depth of breathing. Due to this, the concentration of oxygen and carbon dioxide in arterial blood does not change even under the influence of such active physical activity like working out on a cardio machine or doing weight training. The regulation of breathing is controlled by the respiratory center, which is shown in the figure below.

Structure of the respiratory center of the brain stem: 1- Varoliev Bridge; 2- Pneumotaxic center; 3- Apneustic center; 4- Pre-Bötzinger complex; 5- Dorsal group of respiratory neurons; 6- Ventral group of respiratory neurons; 7- Medulla oblongata. I- Respiratory center of the brain stem; II- Parts of the respiratory center of the bridge; III- Parts of the respiratory center of the medulla oblongata.

The respiratory center consists of several discrete groups of neurons that are located on either side of the lower part of the brain stem. In total, there are three main groups of neurons: the dorsal group, the ventral group and the pneumotaxic center. Let's look at them in more detail.

• Dorsal respiratory group plays vital role in the implementation of the breathing process. It is also the main generator of impulses that set a constant breathing rhythm.
• The ventral respiratory group performs several functions at once important functions. First of all, respiratory impulses from these neurons take part in the regulation of the breathing process, controlling the level of pulmonary ventilation. Among other things, excitation of selected neurons in the ventral group can stimulate inhalation or exhalation, depending on the moment of excitation. The importance of these neurons is especially great since they are able to control the abdominal muscles that take part in the exhalation cycle during deep breathing.
• The pneumotaxic center takes part in controlling the frequency and amplitude of respiratory movements. The main influence of this center is to regulate the duration of the lung filling cycle, as a factor that limits tidal volume. An additional effect of such regulation is a direct effect on respiratory rate. When the duration of the inhalation cycle decreases, the exhalation cycle also shortens, which ultimately leads to an increase in the respiratory rate. The same is true in the opposite case. As the duration of the inhalation cycle increases, the exhalation cycle also increases, while the respiratory rate decreases.

Conclusion

The human respiratory system is primarily a set of organs necessary to provide the body with vital oxygen. Knowledge of the anatomy and physiology of this system gives you the opportunity to understand the basic principles of constructing the training process, both aerobic and anaerobic. The information presented here is of particular importance in determining the goals of the training process and can serve as the basis for assessing the athlete’s health status when planning training programs.

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