Physiological systems of the body. Sanogenetic protection of the brain
In our body, oxygen is responsible for the process of energy production. In our cells, oxygenation occurs only thanks to oxygen - the transformation nutrients(fats and lipids) into cell energy. When the partial pressure (content) of oxygen in the inhaled level decreases, its level in the blood decreases - the activity of the body at the cellular level decreases. It is known that more than 20% of oxygen is consumed by the brain. Oxygen deficiency contributes. Accordingly, when oxygen levels drop, well-being, performance, general tone, and immunity suffer.
It is also important to know that it is oxygen that can remove toxins from the body.
Please note that in all foreign films, in the event of an accident or a person in serious condition, emergency doctors first of all put on an oxygen apparatus to the victim in order to increase the body’s resistance and increase his chances of survival.
The therapeutic effects of oxygen have been known and used in medicine since the end of the 18th century. In the USSR, the active use of oxygen for preventive purposes began in the 60s of the last century.
Hypoxia
Hypoxia or oxygen starvation- reduced oxygen content in the body or individual organs and tissues. Hypoxia occurs when there is a lack of oxygen in the inhaled air and in the blood, when the biochemical processes of tissue respiration are disrupted. Due to hypoxia, irreversible changes develop in vital organs. The most sensitive to oxygen deficiency are the central nervous system, heart muscle, kidney tissue, and liver.
Manifestations of hypoxia are respiratory failure, shortness of breath; dysfunction of organs and systems.
Harm to oxygen
Sometimes you can hear that “Oxygen is an oxidizing agent that accelerates the aging of the body.”
Here, from the correct premise, the wrong conclusion is drawn. Yes, oxygen is an oxidizing agent. Only thanks to it are nutrients from food processed into energy for the body.
The fear of oxygen is associated with two exceptional properties of it: free radicals and poisoning due to excess pressure.
1. What are free radicals?
Some of the huge number of constantly occurring oxidative (energy-producing) and reduction reactions of the body are not completed to the end, and then substances are formed with unstable molecules that have unpaired electrons at the outer electronic levels, called “free radicals”. They try to grab the missing electron from any other molecule. This molecule, turning into a free radical, steals an electron from the next one, and so on..
Why is this necessary? A certain amount of free radicals, or oxidants, is vital for the body. First of all, to combat harmful microorganisms. Free radicals are used by the immune system as “projectiles” against “invaders.” Normally in the human body 5% formed during chemical reactions substances become free radicals.
Scientists cite emotional stress, heavy physical exertion, injury and exhaustion due to air pollution, consumption of canned and technologically incorrectly processed foods, vegetables and fruits grown with herbicides and pesticides, and ultraviolet radiation as the main reasons for the disruption of natural biochemical balance and the increase in the number of free radicals. and radiation exposure.
Thus, aging is a biological process of slowing cell division, and free radicals erroneously associated with aging are natural and necessary for the body defense mechanisms and their harmful effects are associated with violation natural processes in organism negative factors environment and stress.
2. “It’s easy to get poisoned with oxygen.”
Indeed, excess oxygen is dangerous. Excess oxygen causes an increase in the amount of oxidized hemoglobin in the blood and a decrease in the amount of reduced hemoglobin. And, since it is the reduced hemoglobin that removes carbon dioxide, its retention in the tissues leads to hypercapnia - CO2 poisoning.
With an excess of oxygen, the number of free radical metabolites increases, those same terrible “free radicals” that are highly active, acting as oxidizing agents that can damage biological cell membranes.
Terrible, isn't it? I immediately want to stop breathing. Fortunately, in order to become oxygen poisoned, you need increased oxygen pressure, such as in a pressure chamber (during oxygen barotherapy) or when diving with special breathing mixtures. In ordinary life, such situations do not occur.
3. “There is little oxygen in the mountains, but there are many centenarians! Those. oxygen is harmful."
Indeed, in the Soviet Union, a number of centenarians were registered in the mountainous regions of the Caucasus and Transcaucasia. If you look at the list of verified (i.e. confirmed) long-livers of the world throughout its history, the picture will not be so obvious: oldest centenarians, registered in France, the USA and Japan did not live in the mountains..
In Japan, where the oldest woman on the planet, Misao Okawa, who is already more than 116 years old, still lives and lives, there is also the “island of centenarians” Okinawa. The average life expectancy here for men is 88 years, for women - 92; this is higher than the rest of Japan by 10-15 years. The island has collected data on more than seven hundred local centenarians over a hundred years old. They say that: “Unlike the Caucasian highlanders, the Hunzakuts of Northern Pakistan and other peoples who boast of their longevity, all Okinawan births since 1879 have been documented in the Japanese family registry - koseki.” The Okinawans themselves believe that the secret of their longevity rests on four pillars: diet, active image life, self-sufficiency and spirituality. Local residents never overeat, adhering to the principle of “hari hachi bu” - eat eight-tenths full. This “eight-tenths” consists of pork, seaweed and tofu, vegetables, daikon and local bitter cucumber. The oldest Okinawans do not sit idle: they actively work on the land, and their recreation is also active: most of all they like to play local variety croqueta: Okinawa is called the happiest island - there is no characteristic large islands Japan haste and stress. The locals are committed to the philosophy of yuimaru - "a kind-hearted and friendly joint effort."
It is interesting that as soon as Okinawans move to other parts of the country, there are no longer long-livers among such people. Thus, scientists studying this phenomenon have found that the genetic factor does not play a role in the longevity of the islanders. And we, for our part, consider it extremely important that the Okinawa Islands are located in an actively wind-blown zone in the ocean, and the oxygen level in such zones is recorded as the highest - 21.9 - 22% oxygen.
Air purity
“But the air outside is dirty, and oxygen carries all the substances with it.”
That is why OxyHaus systems have a three-stage incoming air filtration system. And the already purified air enters a zeolite molecular sieve, in which air oxygen is separated.
“Is it possible to poison yourself with oxygen?”
Oxygen poisoning, hyperoxia, occurs as a result of breathing oxygen-containing gas mixtures (air, nitrox) at elevated pressure. Oxygen poisoning can occur when using oxygen devices, regenerative devices, when using artificial gas mixtures for breathing, during oxygen recompression, and also due to exceeding therapeutic doses in the process of oxygen barotherapy. With oxygen poisoning, dysfunctions of the central nervous system, respiratory and circulatory system develop.
How does oxygen affect the human body?
A larger amount is required by a growing body and those who engage in intense physical activity. In general, respiratory activity largely depends on many external factors. For example, if you step into a cool enough shower, the amount of oxygen you consume will increase by 100% compared to conditions at room temperature. That is, the more a person gives off heat, the faster his breathing frequency becomes. Here are a few interesting facts on this occasion:
- in 1 hour a person consumes 15-20 liters of oxygen;
- the amount of oxygen consumed: during wakefulness increases by 30-35%, during quiet walking - by 100%, during light work - by 200%, during heavy work physical work- by 600% or more;
- The activity of respiratory processes directly depends on the capacity of the lungs. So, for example, for athletes it is 1-1.5 liters more than normal, but for professional swimmers it can reach up to 6 liters!
- The greater the lung capacity, the lower the breathing rate and the greater the depth of inspiration. An illustrative example: an athlete takes 6-10 breaths per minute, while a common person(non-athlete) breathes at a rate of 14-18 breaths per minute.
So why do we need oxygen?
It is necessary for all life on earth: animals consume it in the process of breathing, and plants They release it during photosynthesis. Each living cell contains more oxygen than any other element - about 70%.
It is found in the molecules of all substances - lipids, proteins, carbohydrates, nucleic acids and low molecular weight compounds. And human life would be simply unthinkable without this important element!
The process of its metabolism is as follows: first it enters the blood through the lungs, where it is absorbed by hemoglobin and forms oxyhemoglobin. Then it is “transported” through the blood to all cells of organs and tissues. In a bound state, it comes in the form of water. In tissues it is spent mainly on the oxidation of many substances during their metabolism. It is further metabolized to water and carbon dioxide, then excreted from the body through the respiratory and excretory systems.
Excess oxygen
Prolonged inhalation of air enriched with this element is very dangerous for human health. High concentrations of O2 can cause the appearance of free radicals in tissues, which are “destroyers” of biopolymers, more precisely, their structure and functions.
However, in medicine, the procedure of oxygen saturation under oxygen is still used to treat some diseases. high blood pressure which is called hyperbaric oxygen therapy.
Excess oxygen is as dangerous as excess solar radiation. In life, a person simply burns slowly in oxygen, like a candle. Aging is a combustion process. In the past, peasants who were constantly in the fresh air and sun lived much less than their masters - nobles who played music in closed houses and spent time playing card games.
Rice. 1. The structure of the spine.
The vertebrae are connected by cartilaginous, elastic intervertebral discs and articular processes. Intervertebral discs increase the mobility of the spine. The greater their thickness, the greater the flexibility. If the curves of the spinal column are strongly expressed (with scoliosis), mobility chest decreases. A flat or rounded back (hunchback) indicates weak back muscles. Posture correction is carried out by general developmental specialists, strength exercises and stretching exercises. The spinal column allows bending forward and backward, to the sides, and rotational movements around a vertical axis.
Rib cage comprises sternum(sternum), 12 thoracic vertebrae and 12 pairs of ribs (Fig. 2).
Rice. 2. Human skeleton.
The ribs are flat, arched-curved long bones, which with the help of flexible cartilaginous ends are movably attached to the sternum. All rib connections are very elastic, which is important for breathing.
The rib cage protects the heart, lungs, liver and part of the digestive tract. The volume of the chest can change during breathing with contraction of the intercostal muscles and diaphragm.
Skeleton upper limbs formed by the shoulder girdle, consisting of two shoulder blades and two clavicles, and the free upper limb, including the shoulder, forearm and hand. The shoulder is one tubular humerus bone; the forearm is formed by the radius and ulna bones; the skeleton of the hand is divided into the wrist (8 bones arranged in two rows), metacarpus (5 short tubular bones) and phalanges of the fingers (5 phalanges).
Skeleton lower limb includes the pelvic girdle, consisting of two pelvic bones and the sacrum, and the skeleton of the free lower limb, which consists of three main sections - the femur (one femur), lower leg (large and small tibia) and feet (tarsus - 7 bones, metatarsus - 5 bones and 14 phalanges).
All bones of the skeleton are connected through joints, ligaments and tendons . Joints provide mobility to the articulating bones of the skeleton. Articular surfaces are covered thin layer cartilage, which ensures the sliding of articular surfaces with low friction. Each joint is completely enclosed in joint capsule. The walls of this bursa secrete joint fluid, which acts as a lubricant. The ligamentous-capsular apparatus and the muscles surrounding the joint strengthen and fix it. The main directions of movement that the joints provide are: flexion-extension, abduction-adduction, rotation and circular movements.
Basic functions of musculoskeletal musculoskeletal system- support and movement of the body and its parts in space.
Main function joints - participate in movements. They also play the role of dampers, dampening the inertia of movement and allowing you to instantly stop while moving.
Properly organized physical education classes do not harm the development of the skeleton; it becomes stronger as a result of the thickening of the cortical layer of bones. This is important when performing physical exercises that require high mechanical strength (running, jumping, etc.). Improper construction of training sessions can lead to overload of the supporting apparatus. One-sidedness in the choice of exercises can also cause skeletal deformation.
People with limited physical activity, whose work is characterized by maintaining a certain position for a long time, experience significant changes in bone and cartilage tissue, which especially adversely affects the condition of the spinal column and intervertebral discs. Classes physical exercise strengthen the spine and, due to the development of the muscular corset, eliminate various curvatures, which contributes to the production correct posture and expansion of the chest.
Any motor activity, including sports, is performed with the help of muscles, due to their contraction. Therefore, the structure and functionality of muscles must be known to any person, but especially to those who engage in physical exercise and sports.
Human skeletal muscles.
A person has about 600 muscles. The main muscles are shown in Fig. 3.
Fig.3. Human muscles.
Muscles of the chest participate in the movements of the upper limbs, and also provide voluntary and involuntary breathing movements. The respiratory muscles of the chest are called the external and internal intercostal muscles. TO respiratory muscles This also applies to the diaphragm.
Back muscles consist of superficial and deep muscles. Superficial ones provide some movements of the upper limbs, head and neck. The deep (“rectifiers of the trunk”) are attached to the spinous processes of the vertebrae and stretch along the spine. The back muscles are involved in maintaining vertical position body, with strong tension (contraction) cause the body to bend backwards.
Abdominal muscles maintain pressure inside the abdominal cavity (abdominals), participate in some body movements (bending the torso forward, bending and turning to the sides), during the breathing process.
Muscles of the head and neck- facial, chewing and moving the head and neck. Facial muscles are attached at one end to the bone, the other to the skin of the face, some can begin and end in the skin. Facial muscles provide movement of the facial skin, reflect various mental states of a person, accompany speech and are important in communication. Chewing muscles when contracting, they cause the lower jaw to move forward and to the sides. The neck muscles are involved in head movements. Back group muscles, including the muscles of the back of the head, with tonic (from the word “tone”) contraction, holds the head in an upright position.
Muscles of the upper limbs provide movement of the shoulder girdle, forearm and move the hand and fingers. The main antagonist muscles are the biceps (flexor) and triceps (extensor) muscles of the shoulder. The movements of the upper limb, and especially the hand, are extremely diverse. This is due to the fact that the hand serves as a human organ of labor.
Muscles lower limbs promotes movement of the hip, leg and foot. Thigh muscles play important role in maintaining an upright body position, but in humans they are more developed than in other vertebrates. The muscles that carry out movements of the lower leg are located on the thigh (for example, the quadriceps muscle, the function of which is to extend the lower leg at the knee joint; the antagonist of this muscle is the biceps femoris muscle). The foot and toes are driven by muscles located on the lower leg and foot. Flexion of the toes is carried out by contraction of the muscles located on the sole, and extension - by contraction of the muscles of the anterior surface of the leg and foot. Many muscles of the thigh, leg and foot are involved in maintaining the human body in an upright position.
There are two types of muscles: smooth(involuntary) and striated(arbitrary). Smooth muscles are found in the walls of blood vessels and some internal organs. They constrict or dilate blood vessels, move food along the gastrointestinal tract, and contract the walls Bladder. Striated muscles are all skeletal muscles that provide a variety of body movements. The striated muscles also include the cardiac muscle, which automatically ensures the rhythmic functioning of the heart throughout life.
The basis of muscles is proteins, making up 80-85% of muscle tissue (excluding water). The main property of muscle tissue is contractility, it is provided thanks to contractile muscle proteins - actin and myosin. Muscle tissue is very complex. A muscle has a fibrous structure, each fiber is a muscle in miniature, the combination of these fibers forms the muscle as a whole. Muscle fiber, in turn, consists of myofibrils. Each myofibril is divided into alternating light and dark areas. Dark areas are made up of long chains of molecules myosin, light ones are formed by thinner protein threads actin.
Muscle activity is regulated by the central nervous system. Each muscle contains a nerve that divides into thin and subtle branches. Nerve endings reach individual muscle fibers. Motor nerve fibers transmit impulses from the brain and spinal cord (excitation), which bring the muscles into working condition, causing them to contract. Sensory fibers transmit impulses in the opposite direction, informing the central nervous system about muscle activity.
Skeletal muscles are part of the structure of the musculoskeletal system, are attached to the bones of the skeleton and, when contracted, move individual parts of the skeleton and levers. They are involved in maintaining the position of the body and its parts in space, provide movement when walking, running, chewing, swallowing, breathing, etc., while generating heat.
Skeletal muscles have the ability to be excited under the influence of nerve impulses. Excitation is carried out to contractile structures (myofibrils), which, in response, perform a certain motor act - movement or tension.
All skeletal muscle consists of striated muscles. In humans, there are about 600 of them and most of them are paired. Muscle accounts for a significant portion of the dry mass of the human body. In women, muscles account for up to 35% total mass body, and in men up to 50%, respectively. Special strength training can significantly increase muscle mass. Physical inactivity leads to a decrease in muscle mass, and often to an increase in fat mass.
Skeletal muscles are covered on the outside with a dense connective tissue membrane. Each muscle has an active part ( muscle body) and passive ( tendon). Tendons have elastic properties and are a consistent elastic element of the muscle. Tendons have greater tensile strength compared to muscle tissue. The weakest and therefore often injured areas of the muscle are the transitions between the muscle and the tendon. Therefore, before each training session, a good preliminary warm-up is necessary.
Muscles are divided into long, short And wide.
Muscles whose action is directed in the opposite direction are called antagonists, and at the same time - synergists.
According to the functional purpose and direction of movement in the joints, muscles are distinguished flexors And extensors, leading And diverting, sphincters(compressive) and expanders.
All muscles are penetrated by a complex system of blood vessels. The blood flowing through them supplies them with nutrients and oxygen.
Functions of the musculoskeletal system:
Support - fixation of muscles and internal organs;
Protective - vital protection important organs(brain and spinal cord, heart, etc.);
Motor - ensuring motor acts;
Spring - softening shocks and shocks;
Hematopoietic - hematopoiesis;
Participation in mineral metabolism.
Physiological systems of the body.
Nervous system. The human nervous system unites all body systems into a single whole and consists of several billion nerve cells and their processes. Long processes of nerve cells unite to form nerve fibers that connect to all human tissues and organs.
Nervous system comprises central(brain and spinal cord) and peripheral(nerves arising from the brain and spinal cord and located on the periphery nerve ganglia) departments.
The central nervous system coordinates the activities of various organs and systems of the body and regulates this activity in a changing external environment using the reflex mechanism. The processes occurring in the central nervous system underlie all mental activity person.
Brain is an accumulation of a huge number of nerve cells. It consists of anterior, intermediate, middle and posterior sections. The structure of the brain is incomparably more complex than the structure of any organ. human body. The brain is active not only during wakefulness, but also during sleep. Brain tissue consumes 5 times more oxygen than the heart and 20 times more than muscles. Making up only about 2% of the human body weight, the brain absorbs 18-25% of the oxygen consumed by the entire body. The brain is significantly superior to other organs in glucose consumption. It uses 60-70% of the glucose produced by the liver, despite the fact that the brain contains less blood than other organs. Deterioration of blood supply to the brain may be associated with physical inactivity. In this case, there is headache varying localization, intensity and duration, dizziness, weakness, decreased mental performance, memory deteriorates, irritability appears.
Spinal cord lies in the spinal canal formed by the vertebral arches. In various parts of the spinal cord there are motor neurons (motor nerve cells) that innervate the muscles of the upper extremities, back, chest, abdomen, and lower extremities. IN sacral region centers for defecation, urination and sexual activity are located. The tone of the spinal cord centers is regulated by the higher parts of the central nervous system. All kinds of injuries and diseases of the spinal cord can lead to disorders of pain and temperature sensitivity, disruption of the structure of complex voluntary movements, muscle tone.
Peripheral nervous system formed by nerves arising from the brain and spinal cord. There are 12 pairs of cranial nerves from the brain, and 31 pairs of spinal nerves from the spinal cord.
By functional principle The nervous system is divided into somatic and autonomic. Somatic the nerves innervate the striated muscles of the skeleton and some organs (tongue, pharynx, larynx, etc.). Vegetative nerves regulate the functioning of internal organs (heart contraction, intestinal peristalsis, etc.).
The main nervous processes are excitation and inhibition that occur in nerve cells. Excitation- the state of nerve cells when they transmit or direct nerve impulses themselves to other cells. Braking- the state of nerve cells when their activity is aimed at restoration.
The nervous system operates on the principle of a reflex. Reflex- this is the body’s response to irritation, both internal and external, carried out with the participation of the central nervous system (CNS).
There are two types of reflexes: unconditional(congenital) and conditional(acquired in the process of life).
All human movements represent new forms of motor acts acquired in the process of individual life. Motor skill- a motor action performed automatically without the participation of attention and thinking.
In the process of physical training, the human nervous system improves, carrying out a more subtle interaction of the processes of excitation and inhibition of various nerve centers. Training allows the sense organs to carry out motor actions in a more differentiated manner and forms the ability to more quickly master new motor skills. The main function of the nervous system is to regulate the interaction of the body as a whole with its environment. external environment and in the regulation of the activities of individual organs and communications between organs.
Receptors and analyzers. The body’s ability to quickly adapt to environmental changes is realized thanks to special education - receptors, which, having strict specificity, transform external stimuli (sound, temperature, light, pressure) into nerve impulses arriving through nerve fibers into the central nervous system.
Human receptors are divided into two main groups: extero- (external) and intero- (internal) receptors. Each such receptor is integral part analyzing system, which is called an analyzer. Analyzer consists of three sections - the receptor, the conductive part and the central formation in the brain. The highest part of the analyzer is the cortical part of the brain. Let us list the names of analyzers whose role in human life is known to many:
Skin (tactile, pain, heat, cold sensitivity);
Motor (receptors in muscles, joints, tendons and ligaments are excited under the influence of pressure and stretching);
Vestibular (located in the inner ear and perceives the position of the body in space);
Visual (light and color);
Auditory (sound);
Olfactory (smell);
Flavoring (taste);
Visceral (condition of a number of internal organs).
Composition and functions of blood.Blood- liquid trophic connective tissue of the body, circulating in the vessels and performing following functions:
Transport - delivers nutrients to cells; provides humoral regulation.
Respiratory - delivers oxygen to tissues;
Excretory - removes metabolic products and carbon dioxide from them;
Protective - ensuring immunity and thrombus formation during bleeding;
Thermoregulatory - regulates body temperature.
The composition of the blood is relatively stable and has a weak alkaline reaction. Blood consists of plasma (55%) and shaped elements (45 %).
Plasma- the liquid part of the blood (90-92% water), containing organic substances and salts (8%), as well as vitamins, hormones, and dissolved gases.
Shaped elements: red blood cells, white blood cells and platelets. The formation of blood cells is carried out in various hematopoietic organs - bone marrow, spleen, lymph nodes.
Red blood cells- red blood cells(4-5 million per cubic mm), are the carrier of the red pigment - hemoglobin. The main physiological function of red blood cells is to bind and transport oxygen from the lungs to organs and tissues. This process is carried out due to the structural features of red blood cells and the chemical composition of hemoglobin. Hemoglobin is unique in that it has the ability to form substances in combination with oxygen. There are 750-800 g of hemoglobin in the body, its concentration in the blood in men is 14-15%, in women 13-14%. Hemoglobin determines the maximum blood capacity (the maximum amount of oxygen that can be contained in 100 ml of blood). Every 100 ml of blood can bind up to 20 ml of oxygen. The combination of hemoglobin with oxygen is called oxyhemoglobin. Red blood cells are formed in red bone marrow cells.
Leukocytes- white blood cells (6-8 thousand in 1 cubic mm of blood). Their main function is to protect the body from pathogens. They protect the body from foreign bacteria by either directly destroying them through phagocytosis (absorption) or by producing antibodies to destroy them. Their lifespan is 2-4 days. The number of leukocytes is constantly replenished due to those newly formed from cells of the bone marrow, spleen and lymph nodes.
Platelets- blood platelets (200-400 thousand/mm3), promote blood clotting and, when broken down, release a vasoconstrictor substance - seratonin.
Circulatory system. The activity of all systems of the human body is carried out through the interaction of humoral (fluid) and nervous regulation. Humoral regulation carried out by an internal transport system through the blood and the circulatory system, which includes the heart, blood vessels, lymphatic vessels and organs that produce special cells - formed elements.
The nervous system enhances or inhibits the activity of all organs not only by waves of excitation or nerve impulses, but also by entering the blood, lymph, spinal and tissue fluid mediators, hormones and metabolic products. These chemicals act on organs and the nervous system. Thus, in natural conditions there is no exclusively nervous regulation of organ activity, but a neurohumoral one.
The movement of blood and lymph through the vessels occurs continuously, due to which organs, tissues, and cells constantly receive what they need in the process of assimilation nutrients and oxygen, and decay products are continuously removed during the metabolic process.
Circulation- This is the process of directed blood movement. It occurs due to the activity of the heart and blood vessels. The main functions of blood circulation are transport, metabolic, excretory, homeostatic, protective. The circulatory system provides transport respiratory gases, nutrients and biologically active substances, hormones, heat transfer within the body.
Blood in the human body moves through closed system, in which two parts are distinguished - the large and small circles of blood circulation. Right side the heart moves blood through the pulmonary circulation, the left side of the heart moves through the systemic circulation (Fig. 4).
Rice. 4. Systemic and pulmonary circulation.
Pulmonary circulation starts from the right ventricle of the heart. The blood then enters pulmonary trunk, which is divided into two pulmonary arteries, which in turn are divided into smaller arteries that pass into the capillaries of the alveoli, where gas exchange occurs (in the lungs, the blood gives off carbon dioxide and is enriched with oxygen). Two veins emerge from each lung and drain into the left atrium.
Systemic circulation starts from the left ventricle of the heart. Blood enriched with oxygen and nutrients flows to all organs and tissues where gas exchange and metabolism occur. Taking carbon dioxide and decay products from the tissues, the blood collects in the veins and moves to the right atrium.
The non-stop movement of blood through the vessels is caused by rhythmic contractions of the heart, which alternate with its relaxation. Due to the pumping function of the heart, creating a pressure difference in the arterial and venous sections the vascular system, as a result of periodic alternation of contractions and relaxations of the ventricles and atria, blood moves through the vessels continuously, in a certain direction. The contraction of the heart muscle is called systole, and her relaxation - diastole. The period including systole and diastole is cardiac cycle.
The activity of the heart is characterized by atrial systole (0.1 s) and ventricular (0.35 s) and diastole (0.45 s).
There are three types of blood vessels in humans: arteries, veins, and capillaries. Arteries and veins differ from each other in the direction of blood movement in them. Arteries carry blood from the heart to the tissues, and veins return it from the tissues to the heart. Capillaries - the finest vessels, they are thinner human hair 15 times.
The heart is the central organ of the circulatory system. The heart is hollow muscular organ, divided by a longitudinal partition into right and left halves. Each of them consists of an atrium and ventricles, separated by fibrous septa (Fig. 5).
Rice. 5. Human heart.
Valve apparatus of the heart- formation that allows blood to pass through vascular system in one direction. In the heart, there are leaflet valves between the atria and ventricles and semilunar valves - at the exit of blood from the ventricles into the aorta and pulmonary artery.
Automaticity of the heart- the ability of the heart to be rhythmically excited without the participation of regulation of the central nervous system. The movement of blood through the vessels is ensured, in addition to the pumping function of the heart, by the suction action of the chest and the dynamic compression of muscle vessels during physical work.
Arterial blood moves through the vessels from the heart under the influence of pressure created by the heart muscle at the time of its contraction. The return movement of blood through the veins is influenced by several factors:
Firstly, venous blood moves towards the heart under the action of contractions of skeletal muscles, which seem to push blood out of the veins towards the heart, while the reverse movement of blood is excluded, since the valves located in the veins allow blood to pass only in the direction of the heart. Forced promotion mechanism venous blood to the heart overcoming the forces of gravity under the influence of rhythmic contractions and relaxation of skeletal muscles, called the muscle pump. Thus, skeletal muscles during cyclic movements significantly help the heart to ensure blood circulation in the vascular system;
Secondly, when inhaling, the chest expands and a reduced pressure is created in it, which ensures the suction of venous blood to the thoracic region;
Thirdly, at the moment of systole (contraction) of the heart muscle, when the atria relax, a suction effect occurs in them, promoting the movement of venous blood to the heart.
The heart works automatically under the control of the central nervous system; a wave of oscillations propagated along the elastic walls of the arteries as a result of the hydrodynamic shock of a portion of blood ejected into the aorta during contraction of the left ventricle is called heart rate(heart rate).
The rhythm of the heart depends on age, gender, body weight, and fitness. In young healthy people, the heart rate (HR) is 60-80 beats per minute. In an adult man at rest it is 65-75 beats/min, in women it is 8-10 beats more than in men. In trained athletes, resting heart rate can reach 40-50 beats/min.
Heart rate less than 60 beats/min is called bradycardia, and more than 90 - tachycardia.
The amount of blood pushed by the ventricle of the heart into the aorta during one contraction is called systolic (stroke) blood volume, at rest it is 60-80 ml. At physical activity in untrained people it increases to 100-130 ml, and in trained ones up to 180-200 ml.
The amount of blood ejected by one ventricle of the heart in one minute is called minute blood volume (MBV). At rest, this figure is on average 4-6 liters. During physical activity, it increases in untrained people to 18-20 l, and in trained ones up to 30-40 l.
The pressure of blood moving through the cardiovascular system is determined mainly by the work of the heart, the resistance of the walls of blood vessels and hydrostatic forces. In the aorta and central arteries systemic circulation, blood pressure (blood pressure) at rest during systole (moment of heart contraction) is 115-125 mm Hg. Art., with diastole (pressure at the moment of relaxation of the heart muscle) is 60-80 mm Hg. Art.
According to the World Health Organization, optimal performance blood pressure the numbers are 120/80.
Normal low for an adult is 100-110/60-70. Below these values, the pressure is hypotonic.
Normal high values include numbers 130-139/85-89. Above these values, the pressure is hypertensive.
Older people have higher blood pressure than younger people; in children it is lower than in adults.
The value of blood pressure depends on the contractile force of the myocardium, the size of the IOC, the length, capacity and tone of blood vessels, and blood viscosity.
Under the influence of physical training, the size and mass of the heart increase due to the thickening of the walls of the heart muscle and an increase in its volume. The muscle of a trained heart is more densely penetrated with blood vessels, which ensures better nutrition of the muscle tissue and its performance.
Breath.Breathing is a complex of physiological, biochemical and biophysical processes that ensure the supply of oxygen to the body, its transport to tissues and organs, as well as its formation, release and removal from the body carbon dioxide and water. The following parts of the respiratory system are distinguished: external respiration, gas transport by blood and tissue respiration.
External breathing carried out using breathing apparatus consisting of the airways (nasal cavity, nasopharynx, larynx, windpipe, trachea and bronchi). The walls of the nasal passage are lined with ciliated epithelium, which traps dust incoming air. The air inside the nasal passage is warmed. When breathing through the mouth, air enters directly into the pharynx and from it into the larynx, without being cleaned or warmed (Fig. 6).
Rice. 6. The structure of the human respiratory apparatus.
When you inhale, air enters the lungs, each of which is in pleural cavity and works in isolation from each other. Each lung is shaped like a cone. From the side facing the heart, a bronchus enters each lung, dividing into smaller bronchi, forming the so-called bronchial tree. Small bronchi end in alveoli, which are intertwined with a dense network of capillaries through which blood flows. As blood passes through the pulmonary capillaries, gas exchange occurs: carbon dioxide, released from the blood, enters the alveoli, which release oxygen into the blood.
Indicators of the performance of the respiratory organs are tidal volume, respiratory rate, vital capacity, pulmonary ventilation, oxygen consumption, etc.
Tidal volume- the volume of air passing through the lungs in one respiratory cycle (inhalation, exhalation), this indicator increases significantly in trained people and ranges from 800 ml or more. In untrained people, the tidal volume at rest is at the level of 350-500 ml.
If, after a normal inhalation, you exhale as much as possible, then another 1.0-1.5 liters of air will come out of the lungs. This volume is usually called reserve The amount of air that can be inhaled beyond the tidal volume is called additional volume.
The sum of three volumes: respiratory, additional and reserve is the vital capacity of the lungs. Vital capacity of the lungs (VC)- the maximum volume of air that a person can exhale after a maximum inhalation (measured by spirometry). The vital capacity of the lungs largely depends on age, gender, height, chest circumference, physical development. In men, vital capacity ranges from 3200-4200 ml, in women 2500-3500 ml. In athletes, especially those involved in cyclic sports (swimming, cross-country skiing, etc.), vital capacity can reach 7000 ml or more in men, 5000 ml or more in women.
Breathing rate- number of respiratory cycles per minute. One cycle consists of inhalation, exhalation and a breathing pause. The average resting respiratory rate is 15-18 cycles per minute. In trained people, due to an increase in tidal volume, the respiratory rate decreases to 8-12 cycles per minute. During physical activity, the respiratory rate increases, for example, in swimmers up to 45 cycles per minute.
Pulmonary ventilation- the volume of air that passes through the lungs in a minute. The amount of pulmonary ventilation is determined by multiplying the tidal volume by the respiratory rate. Pulmonary ventilation at rest is at the level of 5000-9000 ml. With physical activity this figure increases.
Oxygen consumption- the amount of oxygen used by the body at rest or during exercise in 1 minute. At rest, a person consumes 250-300 ml of oxygen per minute. With physical activity this value increases. Largest quantity oxygen that the body can consume per minute at maximum muscle work, called maximum oxygen consumption(IPC).
The respiratory system is most effectively developed by cyclic sports (running, rowing, swimming, skiing, etc.) (Table 1)
Table 1. Some morphofunctional indicators of cardiovascular
E. ZVYAGINA.
Physiological scientists claim that a lack of oxygen in some cases can be beneficial for the body and even help cure many diseases.
Lack of oxygen in organs and tissues (hypoxia) occurs for various reasons.
Laureate of the State Prize of Ukraine, Professor A. Z. Kolchinskaya. Under her leadership, a computer program was created that evaluates the functioning of the respiratory system, and a hypoxic training system was developed.
Hypoxic training session. The patient breathes through the hypoxicator for several minutes, then removes the mask and breathes normal air. The procedure is repeated four to six times.
You can forget how to swim or ride a bike, but breathing is a process that occurs outside of our consciousness. Thank God, no special training is required here. Maybe that's why most of us have extremely rough ideas about how we breathe.
If you ask about this from a person far from natural sciences, the answer will most likely be: we breathe with our lungs. Actually this is not true. It took humanity more than two hundred years to understand what breathing is and what its essence is.
Schematically, the modern concept of breathing can be represented as follows: movements of the chest create conditions for inhalation and exhalation; we inhale air, and with it oxygen, which, passing through the trachea and bronchi, enters the pulmonary alveoli and blood vessels. Thanks to the work of the heart and the hemoglobin contained in the blood, oxygen is delivered to all organs, to every cell. Cells contain tiny grains - mitochondria. It is in them that oxygen is processed, that is, breathing itself takes place.
Oxygen in mitochondria is “picked up” by respiratory enzymes, which deliver it in the form of negatively charged ions to a positively charged hydrogen ion. When oxygen and hydrogen ions combine, they release a large number of heat required for the synthesis of the main storage device of biological energy - ATP (adenosine phosphoric acid). The energy released during the breakdown of ATP is used by the body to carry out all life processes and for any of its activities.
This is how breathing flows in normal conditions: that is, the air contains a sufficient amount of oxygen, and the person is healthy and does not experience overload. But what happens when the balance is upset?
The respiratory system can be compared to a computer. The computer has sensitive elements through which information about the progress of the process is transmitted to the control center. The same sensitive elements are present in the respiratory chain. These are the chemoreceptors of the aorta and carotid arteries, transmitting information about a decrease in oxygen concentration in arterial blood or an increase in carbon dioxide content in it. This happens, for example, in cases where the amount of oxygen in the inhaled air decreases. The signal about this is transmitted through special receptors to the respiratory center of the medulla oblongata, and from there it goes to the muscles. The work of the chest and lungs increases, a person begins to breathe more often, and accordingly, ventilation of the lungs and the delivery of oxygen to the blood improve. Excitation of the receptors in the carotid arteries also causes an increase in heart rate, which increases blood circulation and oxygen reaches the tissues faster. This is also facilitated by the release of new red blood cells into the blood, and therefore the hemoglobin they contain.
This explains beneficial influence mountain air on vitality person. Arriving at mountain resorts - say, in the Caucasus - many people notice that their mood improves, their blood seems to flow faster. And the secret is simple: the air in the mountains is thin, there is less oxygen in it. The body works in the “struggle for oxygen” mode: in order to ensure complete delivery of oxygen to the tissues, it needs to mobilize internal resources. Breathing quickens, blood circulation increases, and as a result, vital forces are activated.
But if you go higher into the mountains, where the air contains even less oxygen, the body will react to its lack in a completely different way. Hypoxia (in scientific terms, lack of oxygen) will be dangerous, and the central nervous system will be the first to suffer from it.
If there is not enough oxygen to support brain function, a person may lose consciousness. Severe hypoxia sometimes even leads to death.
But hypoxia is not necessarily caused low content oxygen in the air. It can be caused by one or another disease. For example, with chronic bronchitis, bronchial asthma and various diseases lungs (pneumonia, pneumosclerosis), not all inhaled oxygen enters the blood. The result is an insufficient supply of oxygen to the entire body. If there are few red blood cells and the hemoglobin contained in them in the blood (as happens with anemia), the entire breathing process suffers. You can breathe often and deeply, but the delivery of oxygen to the tissues will not increase significantly: after all, hemoglobin is responsible for its transport. In general, the circulatory system is directly related to breathing, so interruptions in cardiac activity cannot but affect the delivery of oxygen to the tissues. The formation of blood clots in blood vessels also leads to hypoxia.
So, the functioning of the respiratory system goes wrong with a significant lack of oxygen in the air (for example, high in the mountains), as well as with various diseases. But it turns out that a person can experience hypoxia even if they are healthy and breathe oxygen-rich air. This happens when the load on the body increases. The fact is that in an active state a person consumes significantly more oxygen than in a calm state. Any work - physical, intellectual, emotional - requires certain energy costs. And energy, as we found out, is generated by the combination of oxygen and hydrogen in mitochondria, that is, during respiration.
Of course, the body has mechanisms that regulate the supply of oxygen when the load increases. The same principle applies here as in the case of rarefied air, when the receptors of the aorta and carotid arteries register a decrease in the oxygen concentration in the arterial blood. Excitation of these receptors is transmitted to the cortex cerebral hemispheres brain and all its parts. Ventilation of the lungs and blood supply are increased, which prevents a decrease in the rate of oxygen delivery to organs and cells.
It is curious that in some cases the body can take measures in advance against hypoxia, in particular that occurs during exercise. The basis of this is forecasting future load increases. In this case, the body also has special sensitive elements - they respond to sound, color signals, changes in smell and taste. For example, an athlete, having heard the command “Go!”, receives a signal to reorganize the functioning of the respiratory system. More oxygen begins to flow into the lungs, blood and tissues.
However, an untrained body is often unable to establish adequate oxygen delivery under significant load. And then the person suffers from hypoxia.
The problem of hypoxia has long attracted the attention of scientists. Serious developments were carried out under the leadership of Academician N. N. Sirotinin at the Institute of Physiology named after. A. A. Bogomolets Academy of Sciences of the Ukrainian SSR. A continuation of these studies was the work of Professor A. Z. Kolchinskaya, winner of the State Prize of Ukraine, and her students. They created a computer program that allows one to evaluate the functioning of the human respiratory system using various indicators (volume of air inhaled, rate of oxygen entering the blood, heart rate, etc.). The work was carried out, on the one hand, with athletes and climbers and, on the other hand, with people suffering from certain diseases (chronic bronchitis, bronchial asthma, anemia, diabetes, uterine bleeding, cerebral palsy, myopia, etc.). Computer analysis has shown that even those diseases that seem not to be directly related to the respiratory system have a negative impact on it. It is logical to assume feedback: the functioning of the respiratory system can affect the condition of the entire body.
And then the idea of hypoxic training arose. Let us remember: with a slight decrease in the amount of oxygen in the air (for example, in the foothills), the body activates vital forces. The respiratory system is rebuilt, adapting to new conditions. The volume of respiration increases, blood circulation increases, red blood cells and hemoglobin increase, and the number of mitochondria increases. Such results can be achieved in a clinical setting by providing the patient with a flow of air from reduced content oxygen. For this purpose, a special apparatus was created - a hypoxicator.
But a person cannot be constantly connected to the device. It is necessary to achieve sustainable results and qualitative changes in the respiratory system. For this purpose, it was decided to divide the hypoxic exposure session into series: it turned out that it was under this regime that the mechanisms developed by the body to adapt to hypoxia were strengthened. The patient breathes through a hypoxicator for several minutes (the oxygen content in the supplied air is 11 - 16%), then removes the mask and breathes normal air for some time. This alternation is repeated four to six times. As a result, from session to session, the respiratory, circulatory, hematopoietic organs and those cell organelles that take part in the utilization of oxygen - mitochondria - are trained.
For each patient, the interval hypoxic training regimen is selected individually. It is important to determine the concentration of oxygen in the inhaled air at which the mechanisms of adaptation to hypoxia will begin to operate in the body. Of course, these concentrations are not the same for an athlete and for a patient with bronchial asthma. Therefore, before prescribing a course of treatment, a hypoxic test is performed, which determines the body’s response to inhalation of air with a low oxygen content.
Today, hypoxic training has already proven its effectiveness in treating a wide variety of diseases. First of all, of course, for diseases of the respiratory tract, such as
obstructive chronic bronchitis and bronchial asthma. This alone more than justifies the work of the scientists who developed the method. But the most amazing thing is that with its help those diseases that, at first glance, have nothing to do with breathing can be treated.
For example, as B. Kh. Khatsukov showed, the method turned out to be effective in the treatment of myopia. More than 60% of myopic children who underwent a course of hypoxic training completely restored their vision; for the rest it improved significantly. The fact is that the cause of myopia is poor blood supply and oxygen supply to the ciliary muscle of the eye and the occipital lobes of the cerebral cortex, which regulate vision. In myopic children, the respiratory system lags behind age development. And when it normalizes, vision is restored.
A. 3. Kolchinskaya and her students M. P. Zakusilo and 3. Kh. Abazova conducted successful experiment on the use of hypoxic training for the treatment of hypothyroidism (underactive thyroid gland). When the patient inhaled air with a reduced oxygen content, his thyroid gland began to produce more hormones. After several sessions, the level of hormones in the blood became normal.
Currently, there are already quite a few specialized hypoxic therapy centers operating in Russia and the CIS countries. These centers successfully treat patients with anemia, coronary heart disease, hypertension in the initial stage, neurocirculatory dystonia, diabetes mellitus, some gynecological diseases.
Good results have also been achieved in training athletes. After a 15-day course of hypoxic training, the maximum oxygen consumption of cyclists, rowers and skiers increases by 6%. With normal systematic sports training, this takes about a year. But breathing in such sports is the key to success. Moreover, as we know, it depends on general state organism, its potential.
The effect of hypoxic training is similar to hardening or morning exercises. Just like we train our muscles or boost our immunity by getting wet. cold water, you can “train” the respiratory system. It’s just a pity that you can’t do this kind of gymnastics at home. You still have to pay for your health.
Origin of the brain Savelyev Sergey Vyacheslavovich
§ 6. Brain oxygen consumption
It is completely incorrect to relate the rate of brain metabolism to the total oxygen consumption of the body (Schmidt-Nielsen, 1982). Indeed, in a shrew, oxygen consumption per 1 kg of body weight is 7.4 l/h, and in an elephant it is 0.07 l/h. However, this is the total oxygen consumption, which varies by orders of magnitude in different parts of the body of both the elephant and the shrew. Moreover, in animals with different biology, the amount of oxygen consumption by the same body organs also varies significantly. The idea that oxygen consumption in the brain changes proportionally to body size remains a strange misconception. If any mammal's brain oxygen consumption drops below 12.6 L/(kg-h), death occurs. At this level of oxygen, the brain can only remain active for 10–15 seconds. After 30-120 s, reflex activity fades away, and after 5-6 minutes the death of neurons begins. In other words, nervous tissue has practically no resources of its own. Neither a shrew, nor even an elephant would have any chance of survival if oxygen consumption by the brain were not ensured by special mechanisms. The brain receives oxygen, water with electrolyte solutions and nutrients according to laws that have nothing to do with the metabolic rate of other organs. The consumption values of all “consumable” components are relatively stable and cannot be below a certain level that ensures the functional activity of the brain.
It should be noted that the brain often has a decisive influence on the metabolism of the entire animal. The energy consumption of the brain cannot be below a certain value. Providing this level is achieved in different systematic groups by changing the speed of blood circulation in the vessels of the nervous system. The reason for these differences is changes in the number of capillaries per 1 mm of brain tissue. Of course, in different departments In the brain, the length of the capillaries can vary significantly. Depending on the physiological load, the lumen of the capillaries can also change dynamically. Nevertheless, this very average indicator illuminates the reasons for the increase in heart rate in small mammals. The smaller the capillary network of the brain, the greater the blood flow rate must be to ensure the necessary flow of oxygen and nutrients. You can increase metabolism due to heart rate, breathing and the rate of food consumption. This is what happens in small mammals. Information about the density of capillaries in the brain of animals is very fragmentary. However, there is a general trend showing evolutionary development capillary network brain In a pond frog, the length of capillaries in 1 mm3 of brain tissue is about 160 mm; in a whole-headed cartilaginous fish- 500, in a shark - 100, in an ambystoma - 90, in a turtle - 350, in a tuateria - 100 mm, in a shrew - 400, in a mouse 700, in a rat - 900, in a rabbit - 600, in a cat - 900, in a dog - 900, and in primates and humans - 1200-1400 mm. It should be taken into account that when the length of capillaries is reduced, the area of their contact surface with nerve tissue decreases exponentially. This indicates that in order to maintain a minimum level of oxygen supply to the brain, the shrew's heart must beat several times faster than that of primates and humans. Indeed, for a person this value is 60–90 per minute, and for a shrew it is 130–450. The mass of the shrew's heart should be proportionally greater. In humans it is about 4%, in the capuchin - 8%, and in the shrew - 14% of the total body weight. Consequently, one of the key organs that determines the metabolism of animals is the brain.
Let's try to estimate the real share of energy consumed by the body of animals with different brain and body masses. The large relative mass of the nervous system of small mammals places high demands on the level of metabolism of the brain itself. The costs of maintaining it are comparable to the costs of maintaining the human brain, which have been well researched. The human brain's basic consumption of nutrients and oxygen is approximately 8-10% of the entire body. When the organism is inactive, this value is more or less constant, although it can fluctuate significantly among large and small representatives of a given species. However, even this value is disproportionately large. The human brain makes up 1/50 of the body's weight, and consumes 1/10 of all energy - 5 times more than any other organ. These figures are somewhat underestimated, since oxygen consumption alone is 18%. Let's add the costs of maintaining the spinal cord and peripheral system and we get approximately 1/7. Consequently, in an inactive state, the human nervous system consumes about 15% of the energy of the entire body. Now consider the situation with an actively working brain and peripheral nervous system. According to the most conservative estimates, the energy costs of one brain more than double. Given the generalized increase in activity of the entire nervous system, it can be confidently assumed that about 25–30% of the body’s total expenditure is on its maintenance (Fig. I-8).
The nervous system of mammals turns out to be an extremely “expensive” organ, so the less time the brain works in an intensive mode, the cheaper its maintenance is. The problem is solved in different ways. One of the methods is associated with minimizing the time of intensive operation of the nervous system. This is achieved by a large set of innate, instinctive behavior programs that are stored in the brain as a set of instructions. Instructions for different behaviors require only minor adjustments to suit specific conditions. The brain is hardly used to make individual decisions based on the animal's personal experience. Survival becomes statistical process application of ready-made forms of behavior to specific environmental conditions. The energy costs of maintaining the brain become a limiter of intellectual activity for small animals.
For example, let's say that the American scallopus mole decided to use its brain, like primates or humans. Let's consider the initial conditions. A mole weighing 40 g has a brain weighing 1.2 g and a spinal cord, together with a peripheral nervous system weighing approximately 0.9 g. Having a nervous system that makes up more than 5% of its body weight, the mole spends about 30% of the body’s total energy resources on its maintenance . If he thinks about solving a chess problem, then his body’s expenses for maintaining the brain will double, and the mole himself will instantly die of starvation. Even if a mole pushes an endless earthworm from black caviar, then he will die anyway. The brain will need so much energy that insoluble problems will arise with the rate of oxygen production and the delivery of initial metabolic components from the gastrointestinal tract. Similar difficulties will arise with the removal of metabolic products from the nervous system and its basic cooling. Thus, small insectivores and rodents are doomed not to become chess players. Their brain is instinctive, and the energetic problems of its content pose insurmountable barriers to the development of individual behavior. At the individual level, only variability in the application of innate behavioral programs can arise.
Rice. I-8. Metabolic processes in the brain of primates.
In the metabolism of the nervous system, three main dynamic processes can be distinguished: the exchange of oxygen and carbon dioxide, the consumption of organic substances and the release of catabolic products, the exchange of water and electrolyte solutions. The proportion of these substances consumed by the human brain is indicated at the bottom. The exchange of water and electrolyte solutions is calculated as the time it takes for all the body's water to pass through the brain. The top line is a passive state, the bottom line is the intense work of the nervous system.
However, it is enough to slightly increase the body size, and a qualitatively different situation arises. Gray rat (Rattus rattus) has a nervous system weighing approximately 1/60th of body weight. This is already enough to achieve noticeable decrease relative brain metabolism. There is no point in retelling the results of intellectual experiments and observations of rats, and the degree of individualization of behavior is not comparable to that of moles and shrews. Obvious advantage An increase in body weight is a decrease in the cost of maintaining the brain. Constantly working peripheral parts are not as expensive as the brain, so an increase in body weight leads to a relative “cheaper” brain.
Therefore, to create a customized brain, you need an animal with a sufficiently large body mass. In other words, there is a kind of barrier that, through body size and brain mass, limits the ability of animals to learn and individualize behavior. A small animal with a large brain and high costs of maintaining it will not be able to provide the energy costs to increase its activity. Thus, one cannot expect solutions to complex problems or deep individualization of adaptive behavior. If the animal is large and the brain size is relatively small, then significant fluctuations in the energy costs of its maintenance are acceptable. In this situation, both individualization of behavior and complex processes learning. However, even a large animal with good developed brain there are energy problems. The nervous system is too expensive to be used intensively. The small and intensively working nervous system consumes a colossal share of the body's resources. This situation is unprofitable. An energetically justified solution can only be the short-term use of the brain to solve specific problems. This is what is observed in large mammals. Brief activity is quickly replaced by long-term rest.
Thus, the small and large nervous systems have their advantages. To implement instinctive behavior, you can have a small brain, but its adaptability comes down to modifications of instinct. Big brain It costs its owner quite a lot, but the high energy costs are quite justified. A large brain allows you to cope with complex tasks that do not have ready-made instinctive solutions. The cost of implementing such mechanisms of adaptive behavior is very high, so both animals and humans try to use the brain as little as possible.
Privilege of the nervous system
The nervous system of many animals (and especially mammals) has one property that puts it in an exceptional position. This property is due to its isolation from the rest of the body. Being the main mechanism for integrating the work of internal organs and the basis of behavior, it is a “foreign body” for one’s own body. The immune system views the nervous system much like a splinter. If the immune system “gets” to the brain, then severe autoimmune processes begin that are incompatible with life.
A paradoxical situation arises. The nervous system consumes a huge portion of the oxygen and nutrients of the entire body, which it receives through the blood. At the same time, it must be carefully isolated from the circulatory system, since it is considered by the cells of the immune system as a foreign object.
From the point of view of biological expediency, an obvious contradiction is visible. The main integrating organ should not be foreign to the immune system. Nevertheless, this is a fact for which it is quite easy to find a clear explanation. The brain contains too many specialized organic components that are not used anywhere else in the body. Creating a mechanism in the immune system to recognize them as “our” cells is extremely difficult and unjustified. It is much “cheaper” to simply separate the nervous system from the rest of the body. This principle of isolation is implemented in the testes, ovaries and nervous system. In the very general view The insulation of the nervous system is maintained by the blood-brain barrier, which consists of several types of specialized cells. To understand the isolation of the nervous system from the rest of the body, it is necessary to consider the elementary principles of its structure.
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The amount of oxygen consumed by a person on an empty stomach in a state of muscular rest, lying down, is an indicator of the metabolism necessary to maintain the vital functions of the body at rest, i.e. basal metabolism. Basic human metabolism is characterized by oxygen consumption in the range of 200-250 ml/min with energy consumption of approximately 1-1.2 kcal/min. Basic metabolism is influenced by gender, age, weight and body surface, food composition, climatic conditions, ambient temperature, etc. The basal energy metabolic rate for an adult is taken to be 1 kcal per 1 kg of weight per hour.
Increased oxygen consumption during work is necessary for the oxidation of breakdown products of carbohydrates in the aerobic phase (lactic acid), fats, as well as for the resynthesis of nitrogen-containing substances in the anaerobic phase. The body's need for oxygen is greater, the more work harder. Within certain limits there is linear dependence between the severity of the work performed and oxygen consumption. This compliance is ensured by increased work of the cardiovascular system and an increase in the diffusion coefficient of oxygen through lung tissue. The diffusion coefficient increases from 50 when operating at 450 kg/min to 61 when operating at 1590 kg/min.
The amount of oxygen per minute required for complete oxidation of decay products is called the oxygen demand, or oxygen demand, while the maximum amount of oxygen that the body can receive per minute is called the oxygen ceiling. The oxygen ceiling for people untrained for physical work is approximately 3 l/min, and for trained people it can reach 4-5 l/min.
Energy costs for dynamic negative work are approximately 50% of energy costs for dynamic positive work. Thus, moving a load along a horizontal plane is 9-16 times easier than lifting a load.
Rice. 1. Dynamics of oxygen consumption during physical work. Checkered hatching - oxygen consumption during operation; horizontal shading - oxygen request; vertical shading - oxygen debt. The picture on the left is a medium-heavy job; The picture on the right shows work with progressive oxygen debt.
Oxygen consumption during dynamic positive work is shown in Fig. 1. As can be seen from this figure, the oxygen consumption curve at the beginning of work increases and only after 2-3 minutes it is established at a certain level, which is then maintained for a long time (steady state). The essence of this course of the curve is that at first the work is carried out with incomplete satisfaction of the oxygen demand and, as a result, with an increasing oxygen debt, since the energy processes in the muscle during its contraction occur instantly, and the delivery of oxygen due to the inertia of the cardiovascular and respiratory systems is slow . And only when oxygen delivery fully meets oxygen demand does a steady state of oxygen consumption occur.
The oxygen debt formed at the beginning of work is repaid after the work stops, during the recovery period, during which oxygen consumption reaches the initial level. This is the dynamics of oxygen consumption during light and moderate work. During heavy work, a steady state of oxygen consumption essentially never occurs; the oxygen deficiency at the beginning of the work is supplemented by the oxygen deficiency formed during it. In this case, oxygen consumption increases all the time up to the oxygen ceiling. The recovery period with such work is significantly longer. In the case when the oxygen demand during operation exceeds the oxygen ceiling, the so-called false steady state occurs. It reflects the oxygen ceiling, not the true oxygen demand. The recovery period is even longer.
Thus, the level of oxygen consumption in connection with work can be used to judge the severity of the work performed. A steady state of oxygen consumption during work may indicate that the oxygen demand is fully satisfied, that the accumulation of lactic acid in the muscles and blood does not occur, and that it has time to be resynthesized into glycogen. The absence of a steady state and an increase in oxygen consumption during work indicate the severity of the work, the accumulation of lactic acid, which requires oxygen for its resynthesis. Even more difficult work is characterized by a false steady state.
The duration of the recovery period for oxygen consumption also indicates greater or lesser severity of work. During light work, the oxygen debt is small. The resulting lactic acid, for the most part, manages to be resynthesized into glycogen in the muscles during work; the duration of the recovery period does not exceed several minutes. After hard work, oxygen consumption drops first quickly and then very slowly, the total duration of the recovery period can reach -30 minutes or more.
Restoring oxygen consumption does not mean restoring the impaired functions of the body as a whole. Many functions of the body, for example the state of the respiratory and cardiovascular systems, respiratory coefficient, biochemical processes, etc., have not yet reached the initial level by this time.
For the analysis of gas exchange processes, changes in the respiratory coefficient CO 2 /O 2 (RK) may be of particular interest.
In a steady state of oxygen consumption during operation, DC may indicate the nature of the oxidized substances. During hard work, DC increases to 1, which indicates the oxidation of carbohydrates. After work, DC may be greater than 1, which is explained by a violation of the acid-base balance of the blood and an increase in the concentration of hydrogen ions (pH): the increased pH continues to excite respiratory center and as a result, carbon dioxide is intensively washed out of the blood while oxygen consumption decreases, i.e., in the CO 2 /O 2 ratio, the numerator increases and the denominator decreases.
In a later stage of recovery, DC may be lower than the initial pre-working indicator. This is explained by the fact that in recovery period Alkaline blood reserves are released, and carbon dioxide is retained to maintain normal pH.
During static work, oxygen consumption is of a different nature. In the labor process, the most concrete expression of static work is maintaining a person’s working posture. Working posture as a state of balance of the body can be carried out in order to actively counteract external forces; in this case, prolonged tetanic muscle tension occurs. This type of static work is very uneconomical in terms of innervation and energy. The working posture, in which balance is maintained by adapting to the direction of gravity, is much more economical, since in this case tonic rather than tetanic muscle tension is noted. In practice, both types of static work are observed, often replacing each other, but from the point of view of labor physiology, static work accompanied by tetanic tension is of primary importance. The dynamics of oxygen consumption with this type of static work are shown in Fig. 2.
The diagram shows that during static tension, oxygen consumption is significantly less than oxygen demand, i.e. the muscle works almost under anaerobic conditions. In the period immediately following work, oxygen consumption increases sharply and then gradually decreases (Lingard phenomenon), and the recovery period can be long, so almost all oxygen demand is satisfied after work. Lingard gave the following explanation for the phenomenon he discovered. With tetanic muscle contraction, due to compression of blood vessels, a mechanical obstacle is created to blood flow and thereby to the delivery of oxygen and the outflow of breakdown products - lactic acid. Static work is anaerobic, therefore, the characteristic jump towards increasing oxygen consumption after work is due to the need for oxidation of decomposition products formed during work.
This explanation is not exhaustive. Based on the teachings of N. E. Vvedensky, low oxygen consumption during static work may be due not so much to a mechanical factor as to a decrease in metabolism due to pressor-reflex influences, the mechanism of which is as follows. As a result of static tension (continuous impulses from the muscle), certain cells of the cerebral cortex enter a state of strong prolonged excitation, ultimately leading to inhibitory phenomena such as a parabiotic block. After the cessation of static work (pessimal state), a period of exaltation begins - increased excitability and, as a consequence, an increase in metabolism. The state of increased excitability extends to the respiratory and cardiovascular centers. The described type of static work is low-energy-intensive, oxygen consumption, even with very significant static voltage, rarely exceeds 1 l/min, but fatigue can occur quite quickly, which is explained by changes that have occurred in the central nervous system.
Another type of static work - maintaining a pose through tonic muscle contraction - requires little energy expenditure and is less tiring. This is explained by rare and more or less uniform impulses from the central nervous system, characteristic of tonic innervation, and the characteristics of the contractile reaction itself, rare and weak impulses, viscousness and unity of impulses, and stability of the effect. An example is the habitual standing position of a person.
Rice. 2. Scheme of the Lingard phenomenon.
