The nervous system is the commander of our body, a kind of control system with a complex organization. The nervous system can be divided into the central nervous system, represented by the brain and spinal cord, and the peripheral nervous system, represented by the peripheral nerves (Fig. 35).

There are many ways to transmit nerve impulses, but we will look at the simplest one. The nervous system consists mainly of neurons that have processes through which impulses are transmitted, something like telephone wires (Fig. 35).

The central nervous system consists of the brain and spinal cord, it is the command and thinking center where the nuclei and numerous nerve networks are located. In the cerebral cortex, the thought of raising a hand, taking a step with a foot, or expressing any emotions is formed (Fig. 36).

The signal from the cerebral cortex, passing through many complex structures, enters spinal cord, there it exits through the roots and goes to the muscles that move, for example, an arm or leg (Fig. 37).

We must not forget that nerves can be not only motor, but also sensitive. We touch a hot mug, get burned and remove our hand. This happens because a nerve impulse from neuron receptors located deep in the skin sends information to the brain.

The brain, in turn, instantly transmits information to the motor neuron, and we immediately remove our hand from the hot object so as not to get burned (Fig. 38). Fedor already has two systems, but for some reason there is still no movement.

Respiratory system . Man, like most living beings on our planet, cannot do without air, namely the oxygen it contains. Oxygen in the air is 21% (Fig. 39).

The properties of oxygen are very diverse, and one of its most important properties is its ability to oxidize. With the help of oxygen, vital biochemical processes occur in the body, so a person cannot survive without air. In the absence of oxygen, the brain dies first, after about 5-6 minutes.

How to deliver oxygen to all vital organs? How will oxygen promote muscle movement? Oxygen enters through the nose and through the mouth, through the trachea, through the bronchi, into the alveoli of our lungs (Fig. 40,41).

Oxygen is involved in the transformation of energy; if there is no oxygen, then the energy for muscle movement will not be released and the muscle will not be able to contract. When there is intense stress on muscular system, for example, long running without sufficient preparation, then you may have noticed that your muscles begin to ache (Fig. 42).

Due to the lack of oxygen in the muscles, pyruvic acid is converted into an oxygen-free type, so lactic acid is released and the muscles hurt. Has this ever happened? Now you know why. Fedor has oxygen for the processes of energy release and body movement, but!!! The material itself from which we will obtain energy does not exist, so what should we do? We need to find out where this material for energy comes from.

Digestive system. This is precisely the system (Fig. 43) that supplies our body with the material for life: proteins, fats, carbohydrates, vitamins and all necessary minerals. A person is born weighing 3.5 kg, so why by the age of 23 the mass is 70 kg? We gain weight due to the food we eat. No wonder they say that “we are what we eat.” The way it is. What does the digestive system consist of (Fig. 43)?

First of all, this system consists of oral cavity, pharynx, esophagus, stomach, large and small intestines. There are also auxiliary organs that perform other functions in addition to digestion. These include the liver, pancreas, and salivary glands. The main organic substances, as stated, are proteins, fats and carbohydrates.

Proteins (Fig. 44) are involved in the structure of our body and work as enzymes. In an emergency, other very important functions are used to generate energy.

Carbohydrates (Fig. 45) are simple and complex. Simple carbohydrates are found in the greatest quantities in sweets, and complex carbohydrates are found in porridge and bread. Simple carbohydrates are quickly absorbed and converted into energy or, in excess, converted into fats. Carbohydrates are easy to break down and release a sufficient amount of energy.

Fats (Fig. 46) have a storage function. All energy that is not used is stored as fat in our body.

Food contains different compositions of proteins, fats, carbohydrates and minerals. You can find out the amount of these substances in the product by looking at the back of the label (Fig. 47).

Now let's see how food passes through the digestive system (Fig. 48). Here is a person who ate something, chewing it thoroughly - (1). Then the food goes through the pharynx into the esophagus - (2). From there it enters the stomach, where gastric juice processes what is eaten - (3). Then the food passes into the small intestine (which is approximately 7 meters long), where its absorption begins (4). In the large intestine, all remaining water is absorbed and feces are formed - (5). Through the rectum, feces are removed from the body - (6). The total digestion time can reach 15 hours or more.

The respiratory system consists of the nasal and oral cavities, nasopharynx, larynx, trachea, bronchi, lungs and diaphragm (Fig. 1.8).

Rice. 1.8.

The lungs are a paired organ that has three lobes (upper, middle and lower) that are involved in breathing. Depending on how many lobes of the lung are involved in breathing (inhalation-exhalation), types of breathing are distinguished.

Breathing types:

• thoracic – superficial, in which only the middle lobes of the lungs are involved;
• abdominal breathing - deep, in which the lower lobes of the lung are also included in the work;
• full breathing, when, along with the middle and lower lobes of the lung, the apex of the lung is also filled with air.

Correct breathing:

• exhalation: begins with contraction of the abdominal muscles and diaphragm, continues by reducing the volume of the chest due to movement of the ribs, which ensures the most complete and rational completion of the process of “squeezing” air from the lungs;
• inhale: begins with the operation of the diaphragm (this contributes to better filling lower parts lungs), ends with expansion of the chest.

Oxygen is supplied to the blood through the lungs. At physical activity lung work necessarily increases, i.e. the frequency and depth of breathing increases. In other words, muscle work stimulates the functions of all body systems: workers - cardiovascular and respiratory; regulating – nervous and endocrine.

The functions of the sections of the gastrointestinal tract are as follows (Fig. 1.9).

Rice. 1.9.

Digestive system

• 1. Oral cavity – the breakdown of carbohydrates and bactericidal processing of food begins.
• 2. Stomach – breakdown of complex proteins into simple ones, partial breakdown of fats, destruction of bacteria.
• 3. Small intestine – about 90% of nutrients are absorbed into the blood through its walls.
• 4. Colon – absorption of water, breakdown of complex carbohydrates and fiber from plant foods, formation of toxic substances, some of which enter the blood and are neutralized by the liver.

Nervous system

The nervous system consists of a central (brain and spinal cord) and peripheral (a network of smaller nerves distributed throughout the body) divisions.

The most important functions of the nervous system in the human body are managing the activities of the entire organism and coordinating the processes occurring in the body, depending on the state of the external and internal environment. The nervous system ensures the connection of all parts of the body into a single whole.

The central nervous system lies deep in the body, surrounded and protected by bones (Fig. 1.10).

Rice. 1.10.

The brain is part of the central nervous system and is located inside the cranium. It consists of several components: the cerebrum, cerebellum, brainstem and medulla oblongata.

The spinal cord is the distribution network of the central nervous system. The spinal cord is located inside spinal column and is interconnected with all nerves of the peripheral nervous system.

Peripheral nervous system - represented by nerves extending from the brain and spinal cord.

Vegetative (autonomous) – regulates the activity of internal organs.

Somatic - provides innervation of the body - soma, includes nerve endings that innervate the skin and muscles.

The morphofunctional unit of the nervous system is the nerve cell – neuron. Neurons can be various shapes and size, but they all have a similar structure and consist of a body (soma) and processes. The processes are divided into axons (long) and dendrites (short - numerous branching). Depending on the function they perform, neurons are divided into three main groups: perceivers (sensitive), executive (effector), insertion (contact). Neurons are classified according to the number of their cytoplasmic processes: with two processes - bipolar neurons, more than two - multipolar. Unipolar ones are very rare.

Neurons have only one axon; the other branches are called dendrites. Typically, axons transmit impulses from the neuron body, and dendrites - to it. Neurons are connected to each other through their processes. Intercellular contacts that allow impulses to pass from one neuron to another are called synapses (from the Greek connection, connection). They are located where the axon of one neuron ends with a special structure on another neuron.

Some neurons carry impulses deep into the body and are called afferent (from the Latin afferent), others conduct impulses from deeper areas to muscle cells and are called efferent (from the Latin efferent).

Each segment (structural unit of the body) contains its own afferent and efferent neurons. Communication between segments is carried out by connecting neurons located in the spinal cord. At the head, the spinal cord expands to form the brain, which houses countless neurons. That is, all connecting neurons are located in the central nervous system.

Some of the afferent and efferent neurons belonging to a certain segment are also located in the central nervous system. The other part, lying outside the central nervous system, makes up the peripheral nervous system.

Ensuring the relationship between individual organs and systems of the body, coordinating and combining their functions, communicating the body with the external environment, adapting to the external environment, and the behavior of humans and animals determines the central nervous system. It includes head And spinal cord.

The brain performs many complex processes, and specific zones are responsible for each of them (Fig. 1.11).

Rice. 1.11.

There is a two-way circular connection between the nerve centers and peripheral organs. Any activity is accompanied by the appearance of afferent impulses in the receptors of working organs, signaling the central nervous system about the results of this activity. The body's response to stimulation involving the central nervous system is called reflex, and the path along which impulses travel during the implementation of the reflex is reflex arc.

Reflex is the body’s response to various influences, carried out using the nervous system.

The factor that initiates any reflex response is stimulus, which can act on the body from both the external and internal environment.

Reflexes of the whole organism are divided into unconditioned and conditioned. Unconditional - These are innate, hereditarily transmitted reactions of the body. Conditional – reactions acquired by the body in the process individual development based on unconditioned reflexes. Distinguish extero- (from the outer surface of the body), intero- (from internal organs and blood vessels) and proprio- (from skeletal muscles, joints, tendons) reflexes. According to the nature of the response, reflexes are divided into motor (motor), where the performer is a muscle; secretory, which end with the secretion of glands; vasomotor, regulating the lumen of blood vessels.

The structural and functional basis of a reflex of any complexity is reflex arc, including the following components: receptor, afferent pathway, nerve center, efferent pathway and effector (Fig. 1.12,1.13).

Rice. 1.12.

Rice. 1.13.

Sensor system (analyzer ) - a set of specialized nervous structures that carry out the perception of certain stimuli, the conduction of the resulting excitations, and their higher analysis. In accordance with the specificity of the action of stimuli, the following analyzers are distinguished: visual, auditory, vestibular, gustatory, olfactory, proprioceptive, temperature, etc.

Each analyzer includes three main sections: peripheral (1), consisting of receptors and special formations (eye, ear, etc.): conductive (2), including pathways and subcortical centers; cortical (3), to which information is addressed.

The element of the analyzer that receives information is receptor.

Receptors - these are final structures specially designed to convert the energy of stimuli into impulses for excitation of nerve cells. For each type of receptor there are adequate stimuli to which they are extremely sensitive. Towards environment receptors are divided into internal (interoreceptors ) And external (exteroceptors ); by the nature of the stimulus - mechano-, photo-, chemo-, thermo-, electrical, pain receptors; method of perception of irritation - contact, distant, primary and secondary sensory.

Function of sensory systems (SS), i.e. analyzers, consists in obtaining information from the external and internal environment necessary for organizing purposeful activities to meet the needs of the body.

The importance of sensory systems during exercise physical exercise and sport is defined as follows.

In complex coordination sports, which require accuracy and the highest reliability of assessing the position of the body and its parts in space, the temporal spatial and power parameters of movements, the level of skill is determined primarily by the excitability and sensitivity of such SS as motor, cutaneous, vestibular and some others.

In cyclic sports, where, along with the power and capacity of energy supply systems, the reduction of specific energy consumption per unit of distance is of decisive importance, thanks to the improvement of physical exercise techniques, multiple savings in energy consumption are achieved. And this becomes possible thanks to the heightened sensitivity of a number of SS, the complex functioning of which creates specific sensations of interaction between the body and the environment.

IN sports games The role of the visual SS should be highlighted. In some sports, decreased sensitivity may be beneficial.

In all sports, the role of the motor SS is greatest, since it provides information about the most important parameters of movements and, at the stage of automation of a motor skill, remains the only channel of reverse afferentation, which is used to control the gradual results of sports exercises.

Respiratory system The human body performs the vital function of gas exchange, delivering oxygen to the body and removing carbon dioxide.

It consists of the nasal cavity, pharynx, larynx, trachea and bronchi.

In the area of ​​the pharynx there is a connection between the oral and nasal cavities. Functions of the pharynx: moving food from the mouth into the esophagus and carrying air from the nose (or mouth) to the larynx. The respiratory and digestive tracts intersect in the pharynx.

The larynx connects the pharynx to the trachea and contains the voice box.

The trachea is a cartilaginous tube about 10-15 cm long. To prevent food from entering the trachea at its entrance, a so-called palatine curtain is located. Its purpose is to block the path to the trachea every time food is swallowed.

The lungs consist of bronchi, bronchioles and alveoli, surrounded by a pleural sac.

How does gas exchange occur?

During inhalation, air is drawn into the nose, in the nasal cavity the air is purified and moistened, then it goes down through the larynx into the trachea. The trachea is divided into two tubes - bronchi. Through them, air enters the right and left lungs. The bronchi branch into many tiny bronchioles, which end in alveoli. Through the thin walls of the alveoli, oxygen enters the blood vessels. This is where the pulmonary circulation begins. Oxygen is picked up by hemoglobin, which is contained in red blood cells, and oxygenated blood is sent from the lungs to the left side of the heart. The heart pushes blood into the blood vessels and begins big circle blood circulation, from where oxygen is distributed throughout the body through the arteries. As soon as the oxygen from the blood is used up, the blood flows through the veins to the right side of the heart, the systemic circulation ends, and from there back to the lungs, the pulmonary circulation ends. When you exhale, carbon dioxide is removed from the body.

With each breath, not only oxygen enters the lungs, but also dust, germs and other foreign objects. On the walls of the bronchi there are tiny villi that trap dust and germs. In the walls of the airways, special cells produce mucus that helps clean and lubricate these villi. Contaminated mucus is removed through the bronchi to the outside and coughed up.

Yogic breathing techniques are aimed at cleansing the lungs and increasing their volume. For example, Ha-exit, stepped exhalations, punching and tapping the lungs, full yogic breathing: upper clavicular, costal or thoracic and diaphragmatic or abdominal. It is believed that abdominal breathing is more “correct and beneficial” for human health. The diaphragm is a dome-shaped muscle formation that separates chest from abdominal cavity and also participates in breathing. When you inhale, the diaphragm goes down and the lower part of the lungs fills; when you exhale, the diaphragm rises. Why is diaphragmatic breathing correct? Firstly, most of the lungs are involved, and secondly, the internal organs are massaged. The more we fill our lungs with air, the more actively we saturate the tissues of our body with oxygen.

Digestive system.

The main parts of the digestive canal are: oral cavity, pharynx, esophagus, stomach, small intestine and large intestine, liver and pancreas.

The digestive system performs the functions of mechanical and chemical processing of food, absorption of digested proteins, fats and carbohydrates into the blood and lymph and excretion of undigested substances from the body.

This process can be described differently: digestion is the consumption of energy contained in foods in order to increase or rather maintain one’s own constantly decreasing energy at a certain level. The release of energy from foods occurs during the breakdown of food. We recall the lectures of Marva Vagarshakovna Ohanyan, the concept of phytocalories, which products contain energy and which do not.

Let's return to the biological process. In the oral cavity, food is crushed, moistened with saliva, and then enters the pharynx. Through the pharynx and esophagus, which passes through the chest and diaphragm, crushed food enters the stomach.

In the stomach, food is mixed with gastric juice, the active components of which are hydrochloric acid and digestive enzymes. Peptin breaks down proteins into amino acids, which are immediately absorbed into the blood through the walls of the stomach. Food stays in the stomach for 1.5-2 hours, where it softens and dissolves under the influence of an acidic environment.

The next stage: partially digested food enters the small intestine - duodenum. Here, on the contrary, the environment is alkaline, suitable for the digestion and breakdown of carbohydrates. The duodenum contains a duct from the pancreas, which releases pancreatic juice, and a duct from the liver, which releases bile. It is in this section of the digestive system that food is digested under the influence of pancreatic juice and bile, and not in the stomach, as many people think. IN small intestine Most of the nutrients are absorbed through the intestinal wall into the blood and lymph.

Liver. The barrier function of the liver is to cleanse the blood from the small intestine, so along with substances that are beneficial to the body, those that are not beneficial are also absorbed, such as: alcohol, medications, toxins, allergens, etc., or more dangerous: viruses, bacteria, microbes.

The liver is the main “laboratory” of breakdown and synthesis large quantity organic substances, we can say that the liver is a kind of storehouse of nutrients for the body, as well as a chemical factory, “built in” between two systems - digestion and blood circulation. Imbalance in the action of this complex mechanism is the cause of numerous diseases of the digestive tract and cardiovascular system. There is a very close connection between the digestive system, the liver and the circulatory system. The colon and rectum complete the digestive tract. In the large intestine, water is mainly absorbed and formed feces are formed from food gruel (chyme). Through the rectum, everything unnecessary is removed from the body.

Nervous system

The nervous system includes the brain and spinal cord, as well as nerves, ganglia, and plexuses. All of the above mainly consists of nerve tissue, which:

capable of being excited under the influence of irritation from the environment internal or external to the body and conducting excitation in the form of a nerve impulse to various nerve centers for analysis, and then transmitting the “order” generated in the center to the executive organs to carry out the body’s response in the form of movement (movement in space) or changes in the function of internal organs.

Brain - part central system located inside the skull. Consists of a number of organs: the cerebrum, cerebellum, brainstem and medulla oblongata. Each part of the brain has its own functions.

The spinal cord forms the distribution network of the central nervous system. It lies inside the spinal column, and all the nerves that form the peripheral nervous system depart from it.

Peripheral nerves - are bundles or groups of fibers that transmit nerve impulses. They can be ascending, i.e. transmit sensations from the whole body to the central nervous system, and descending, or motor, i.e. deliver commands from nerve centers to all parts of the body.

Some components peripheral system have distant connections with the central nervous system; they function with very limited control from the central nervous system. These components work independently and constitute the autonomic, or autonomic, nervous system. It controls the functioning of the heart, lungs, blood vessels and other internal organs. Digestive tract has its own internal vegetative system.

The anatomical and functional unit of the nervous system is the nerve cell - neuron. Neurons have processes with which they connect with each other and with innervated formations (muscle fibers, blood vessels, glands). The processes of a nerve cell have different functional significance: some of them conduct stimulation to the neuron body - these are dendrites, and only one process - the axon - from the nerve cell body to other neurons or organs. The processes of neurons are surrounded by membranes and combined into bundles, which form nerves. The membranes isolate the processes of different neurons from each other and contribute to the conduction of excitation.

Irritation is perceived by the nervous system through the senses: eyes, ears, organs of smell and taste, and special sensitive nerve endings - receptors located in the skin, internal organs, blood vessels, skeletal muscles and joints. They transmit signals through the nervous system to the brain. The brain analyzes the transmitted signals and forms a response.

Human respiratory system- a set of organs that provide the function of external respiration (gas exchange between inhaled atmospheric air and blood circulating in the pulmonary circulation).

Gas exchange takes place in the alveoli of the lungs, and is normally aimed at capturing oxygen from the inhaled air and releasing carbon dioxide formed in the body into the external environment.

An adult, at rest, makes an average of 14 respiratory movements per minute, but the respiratory rate can undergo significant fluctuations (from 10 to 18 per minute). An adult takes 15-17 breaths per minute, and a newborn baby takes 1 breath per second. Ventilation of the alveoli is carried out by alternating inhalations ( inspiration) and exhalation ( expiration). When you inhale, atmospheric air enters the alveoli, and when you exhale, air saturated with carbon dioxide is removed from the alveoli. Breathing does not stop working from the birth of a person until his death, because without breathing our body cannot exist. It has been proven that an adult exhales 4 glasses of water per day (≈800 ml), and a child exhales about two (≈ 400 ml).

Based on the method of chest expansion, two types of breathing are distinguished:

§ chest type of breathing (the chest expands by raising the ribs), more often observed in women;

§ abdominal type of breathing (expansion of the chest is achieved by flattening the diaphragm), more often observed in men.

Main functions: breathing, gas exchange.

In addition, the respiratory system is involved in such important functions as thermoregulation, voice production, smell, and humidification of inhaled air. Lung tissue also plays important role in processes such as hormone synthesis, water-salt and lipid metabolism. In a richly developed vascular system blood is deposited in the lungs. The respiratory system also provides mechanical and immune protection against environmental factors.

Digestive system person consists of from alimentary canal: oral cavity, pharynx, esophagus, stomach, small intestine, large intestine and digestive glands(salivary glands, liver and gallbladder, pancreas).

Go to functions alimentary canal include:

· Mechanical restoration– grinding, motility – promotion and excretion of waste.

· Making a secret digestive glands and chemical breakdown of nutrients.

· Suction proteins, carbohydrates and fats, minerals, vitamins, water.

The digestive system, especially in newborns, actively participates in the formation of immunity. After all, a very large number of microorganisms end up in gastrointestinal tract, which at this stage represents a kind of barrier and analyzer.

12. Negative reactions of the body during exercise physical culture and sports. “Dead Point”, “Second Wind”.

TO negative reactions the body during physical exercise and sports include: fatigue and overtraining, fainting, acute physical overstrain, gravitational and hypoglycemic shocks, orthostatic collapse, sun and heat stroke, acute myositis.
With prolonged intense muscular work, the supply of energy resources gradually disappears, substance withdrawal products accumulate in the blood, and impulses entering the cerebral cortex from working skeletal muscles lead to disruption of the normal relationship between the processes of excitation and inhibition. These changes are accompanied by objective sensations that make it difficult to perform physical work, as a result, the body’s performance decreases, and a state of fatigue sets in.

A temporary decrease in performance is called a “dead point”; the state of the body after overcoming it is called a “second wind”. These two states are characteristic of cyclic work of high and moderate power.

In the “dead spot” state, breathing increases significantly, pulmonary ventilation increases, and oxygen is actively absorbed. Despite the fact that the excretion of carbon dioxide also increases, its tension in the blood and alveolar air increases.

The heart rate increases sharply, blood pressure rises, and the amount of under-oxidized products in the blood increases.

When leaving the “dead point” due to the lower intensity of work, pulmonary ventilation remains elevated for some time (it is necessary to free the body from the carbon dioxide accumulated in it), the process of sweating is activated (the mechanism of heat regulation is established), the necessary relationships between excitatory and inhibitory processes are created in the central nervous system. During high-intensity work (maximum and submaximal power), a “second wind” does not occur, so it is continued against the background of increasing fatigue.

Different duration and power of work also determine different timing for the occurrence of a “dead point” and recovery from it. So, during 5 and 10 km races it occurs 5-6 minutes after the start of the run. At longer distances, the “dead spot” occurs later and may occur again. More trained people, adapted to specific loads, overcome the “dead spot” state much easier and more painlessly.

Respiratory system The human body performs the vital function of gas exchange, delivering oxygen to the body and removing carbon dioxide.

It consists of the nasal cavity, pharynx, larynx, trachea and bronchi.

In the area of ​​the pharynx there is a connection between the oral and nasal cavities. Functions of the pharynx: moving food from the mouth into the esophagus and carrying air from the nose (or mouth) to the larynx. The respiratory and digestive tracts intersect in the pharynx.

The larynx connects the pharynx to the trachea and contains the voice box.

The trachea is a cartilaginous tube about 10-15 cm long. To prevent food from entering the trachea at its entrance, a so-called palatine curtain is located. Its purpose is to block the path to the trachea every time food is swallowed.

The lungs consist of bronchi, bronchioles and alveoli, surrounded by a pleural sac.

How does gas exchange occur?

During inhalation, air is drawn into the nose, in the nasal cavity the air is purified and moistened, then it goes down through the larynx into the trachea. The trachea is divided into two tubes - bronchi. Through them, air enters the right and left lungs. The bronchi branch into many tiny bronchioles, which end in alveoli. Through the thin walls of the alveoli, oxygen enters the blood vessels. This is where the pulmonary circulation begins. Oxygen is picked up by hemoglobin, which is contained in red blood cells, and oxygenated blood is sent from the lungs to the left side of the heart. The heart pushes blood into the blood vessels, a large circle of blood circulation begins, from where oxygen is distributed throughout the body through the arteries. As soon as the oxygen from the blood is used up, the blood flows through the veins to the right side of the heart, the systemic circulation ends, and from there back to the lungs, the pulmonary circulation ends. When you exhale, carbon dioxide is removed from the body.

With each breath, not only oxygen enters the lungs, but also dust, germs and other foreign objects. On the walls of the bronchi there are tiny villi that trap dust and germs. In the walls of the airways, special cells produce mucus that helps clean and lubricate these villi. Contaminated mucus is removed through the bronchi to the outside and coughed up.

Yogic breathing techniques are aimed at cleansing the lungs and increasing their volume. For example, Ha-exit, stepped exhalations, punching and tapping the lungs, full yogic breathing: upper clavicular, costal or thoracic and diaphragmatic or abdominal. It is believed that abdominal breathing is more “correct and beneficial” for human health. The diaphragm is a dome-shaped muscle formation that separates the chest from the abdominal cavity and is also involved in breathing. When you inhale, the diaphragm goes down and the lower part of the lungs fills; when you exhale, the diaphragm rises. Why is diaphragmatic breathing correct? Firstly, most of the lungs are involved, and secondly, the internal organs are massaged. The more we fill our lungs with air, the more actively we saturate the tissues of our body with oxygen.

Digestive system.

The main parts of the digestive canal are: oral cavity, pharynx, esophagus, stomach, small intestine and large intestine, liver and pancreas.

The digestive system performs the functions of mechanical and chemical processing of food, absorption of digested proteins, fats and carbohydrates into the blood and lymph and excretion of undigested substances from the body.

This process can be described differently: digestion is the consumption of energy contained in foods in order to increase or rather maintain one’s own constantly decreasing energy at a certain level. The release of energy from foods occurs during the breakdown of food. We recall the lectures of Marva Vagarshakovna Ohanyan, the concept of phytocalories, which products contain energy and which do not.

Let's return to the biological process. In the oral cavity, food is crushed, moistened with saliva, and then enters the pharynx. Through the pharynx and esophagus, which passes through the chest and diaphragm, crushed food enters the stomach.

In the stomach, food is mixed with gastric juice, the active components of which are hydrochloric acid and digestive enzymes. Peptin breaks down proteins into amino acids, which are immediately absorbed into the blood through the walls of the stomach. Food stays in the stomach for 1.5-2 hours, where it softens and dissolves under the influence of an acidic environment.

The next stage: partially digested food enters the small intestine - the duodenum. Here, on the contrary, the environment is alkaline, suitable for the digestion and breakdown of carbohydrates. The duodenum contains a duct from the pancreas, which releases pancreatic juice, and a duct from the liver, which releases bile. It is in this section of the digestive system that food is digested under the influence of pancreatic juice and bile, and not in the stomach, as many people think. The small intestine is where most of the absorption of nutrients occurs through the intestinal wall into the blood and lymph.

Liver. The barrier function of the liver is to cleanse the blood from the small intestine, so along with substances that are beneficial to the body, those that are not beneficial are absorbed, such as alcohol, medications, toxins, allergens, etc., or more dangerous ones: viruses, bacteria, microbes.

The liver is the main “laboratory” for the breakdown and synthesis of a large number of organic substances; we can say that the liver is a kind of storehouse of nutrients for the body, as well as a chemical factory, “built in” between two systems - digestion and blood circulation. An imbalance in the action of this complex mechanism is the cause of numerous diseases of the digestive tract and cardiovascular system. There is a very close connection between the digestive system, the liver and the circulatory system. The colon and rectum complete the digestive tract. In the large intestine, water is mainly absorbed and formed feces are formed from food gruel (chyme). Through the rectum, everything unnecessary is removed from the body.

Nervous system

The nervous system includes the brain and spinal cord, as well as nerves, ganglia, and plexuses. All of the above primarily consists of nervous tissue, which:

capable of being excited under the influence of irritation from the environment internal or external to the body and conducting excitation in the form of a nerve impulse to various nerve centers for analysis, and then transmitting the “order” generated in the center to the executive organs to carry out the body’s response in the form of movement (movement in space) or changes in the function of internal organs.

The brain is part of the central system located inside the skull. Consists of a number of organs: the cerebrum, cerebellum, brainstem and medulla oblongata. Each part of the brain has its own functions.

The spinal cord forms the distribution network of the central nervous system. It lies inside the spinal column, and all the nerves that form the peripheral nervous system depart from it.

Peripheral nerves are bundles or groups of fibers that transmit nerve impulses. They can be ascending, i.e. transmit sensations from the whole body to the central nervous system, and descending, or motor, i.e. deliver commands from nerve centers to all parts of the body.

Some components of the peripheral system have distant connections with the central nervous system; they function with very limited control from the central nervous system. These components work independently and constitute the autonomic, or autonomic, nervous system. It controls the functioning of the heart, lungs, blood vessels and other internal organs. The digestive tract has its own internal autonomic system.

The anatomical and functional unit of the nervous system is the nerve cell - neuron. Neurons have processes with which they connect with each other and with innervated formations (muscle fibers, blood vessels, glands). The processes of a nerve cell have different functional significance: some of them conduct stimulation to the neuron body - these are dendrites, and only one process - the axon - from the nerve cell body to other neurons or organs. The processes of neurons are surrounded by membranes and combined into bundles, which form nerves. The membranes isolate the processes of different neurons from each other and contribute to the conduction of excitation.

Irritation is perceived by the nervous system through the senses: eyes, ears, organs of smell and taste, and special sensitive nerve endings - receptors located in the skin, internal organs, blood vessels, skeletal muscles and joints. They transmit signals through the nervous system to the brain. The brain analyzes the transmitted signals and forms a response.