General characteristics and significance of the musculoskeletal system. Musculoskeletal system
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The musculoskeletal system includes the skeleton and muscles, combined into a single musculoskeletal system. The functional significance of this system lies in its very name. The skeleton and muscles are the supporting structures of the body, limiting the cavities in which internal organs. With the help of the musculoskeletal system, one of the most important functions of the body is movement. Movement is the main external manifestation of the activity of the organism and, at the same time, a necessary factor in its development. In conditions of restriction of movements, both physical and mental development are sharply slowed down. It is shown that if newborn animals are deprived of the possibility of free movement, then already in the first month their weight becomes 3 times less than that of individuals of the same litter. Motor activity, especially hand movements, is one of the necessary conditions for the normal development of the brain, its speech function and thinking. Motor activity also plays an important role in metabolic processes, positively affects the work of all internal organs.
Knowledge of the age characteristics of the organs of movement and the conditions conducive to their normal development is necessary for the development effective means and methods of physical education, labor training, organization of the daily routine.
Skeleton - structural basis
body. The skeleton forms the structural basis of the body and largely determines its shape and size. The skeleton consists of bones, in an adult there are more than 200 of them. The role of the bones is not limited to the support function. The mineral salts that are part of their tissues are one of the most important elements of metabolic processes. The bones also contain one of the main organs of hematopoiesis - the bone marrow.
Each bone is a complex organ consisting of bone tissue, periosteum, bone marrow, blood and lymphatic vessels and nerves.
The bone, with the exception of the connecting surfaces, is covered with periosteum. This is a thin connective tissue sheath, which is rich in nerves and blood vessels that penetrate from it into the bone through special openings. Ligaments and muscles are attached to the periosteum. The inner layer of the periosteum consists of cells that grow and multiply, ensuring the growth of the bone in thickness, and in case of fractures, the formation of callus.
The structure of bones provides their main property - mechanical strength. The properties of the bone are also provided by their chemical composition. Bones contain 60% minerals, 30% organic, 10% water.
The mineral substances of the bone are represented by salts of calcium, phosphorus, magnesium; many trace elements have been found (aluminum, fluorine, manganese, lead, strontium, uranium, cobalt, iron, molybdenum, etc.). In an adult, about 1200 g of calcium, 530 g of phosphorus, 11 g of magnesium are concentrated in the skeleton; 99% of the calcium in the human body is found in the bones. Organic substances include fibrous protein-collagen, carbohydrates, and enzymes. Minerals, especially calcium, make bones hard, organic substances give them elasticity. In children, organic matter predominates in the bone tissue;
their skeleton is flexible, elastic, and therefore it is easily deformed, bent under prolonged and heavy load and incorrect body positions. As we age, the mineral content of bones increases, causing bones to become less elastic and more brittle.
Organic and mineral substances make the bone strong, hard and elastic, and in combination with the structural features of bone tissue, the location of its plates, oriented in the direction of pressure and stretching forces, give the bone properties that surpass many Construction Materials and metals. Thus, bone is 30 times harder than brick and 2.5 times harder than granite. Bone is stronger than oak. It is 9 times stronger than lead and almost as strong as cast iron.
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Musculoskeletal system
Abstract on biology on the topic:
"The musculoskeletal system"
Pupil 9 "G" class
secondary school number 117
SWAD Moscow
Yuditsky Alexander.
Moscow 2004
Plan:
I. Introduction.
II. Skeleton.
1. Spine.
2. Chest.
3. Limbs.
4. Leg and arm.
III. Two types of muscle tissue.
1.Smooth muscles.
2. Muscles of the skeleton.
3. Nerve connections in the muscles.
4. Muscles generate heat.
5. Strength and speed of muscle contraction.
IV. Tiredness and rest.
1. Causes of fatigue.
V. Statics and dynamics of the human body.
1. Conditions of equilibrium.
VI. Everyone needs sports.
1. Muscle training.
2. Labor and sport.
3. Anyone can become an athlete.
VII. Great people about the benefits of exercise.
VIII. Conclusion.
XI. List of used literature.
Musculoskeletal system
The musculoskeletal system consists of bones of the skeleton with joints, ligaments and muscles with tendons, which, along with movements, provide the supporting function of the body. Bones and joints participate passively in movement, obeying the action of muscles, but play a leading role in the implementation of the supporting function. A certain shape and structure of the bones give them greater strength, the reserve of which for compression, expansion, bending significantly exceeds the loads possible during the daily work of the musculoskeletal system. For example, the human tibia can withstand a load of more than a ton during compression, and in terms of tensile strength it is almost as good as cast iron. Ligaments and cartilage also have a large margin of safety.
Skeleton
The skeleton is made up of interconnected bones. It provides our body with support and shape retention, and also protects the internal organs. An adult human skeleton consists of about 200 bones. Each bone has a certain shape, size and occupies a certain position in the skeleton. Part of the bones are interconnected by movable joints. They are driven by muscles attached to them.
Spine. The original structure that makes up the main support of the skeleton is the spine. If it consisted of a solid bone rod, then our movements would be constrained, devoid of flexibility and would deliver the same unpleasant sensations as riding a cart without springs on a cobblestone pavement.
The elasticity of hundreds of ligaments, cartilage layers and bends makes the spine a strong and flexible support. Thanks to this structure of the spine, a person can bend down, jump, somersault, run. Very strong intervertebral ligaments allow the most complex movements and at the same time create reliable protection for the spinal cord. It is not subjected to any mechanical stretching, pressure under the most incredible curves of the spine.
The bends of the spinal column correspond to the influence of the load on the axis of the skeleton. Therefore, the lower, more massive part becomes a support when moving; the upper, with free movement, helps to maintain balance. The vertebral column could be called the vertebral spring.
Wavy curves of the spine provide its elasticity. They appear with the development of the motor abilities of the child, when he begins to hold his head, stand, walk.
Rib cage. The thorax is formed by the thoracic vertebrae, twelve pairs of ribs, and a flat sternum, or sternum. The ribs are flat curved bones. Their rear ends are movably connected to the thoracic vertebrae, and the front ends of the ten upper ribs are connected to the sternum with the help of flexible cartilage. This ensures the mobility of the chest during breathing. The two lower pairs of ribs are shorter than the rest and terminate freely. The chest protects the heart and lungs, as well as the liver and stomach.
It is interesting to note that the ossification of the chest occurs later than other bones. By the age of twenty, the ossification of the ribs ends, and only by the age of thirty does the complete fusion of the parts of the sternum, consisting of the handle, the body of the sternum and the xiphoid process, occur.
The shape of the chest changes with age. In a newborn, it has, as a rule, the shape of a cone with the base turned down. Then the circumference of the chest in the first three years increases faster than the length of the body. Gradually, the cone-shaped chest acquires a rounded shape characteristic of a person. Its diameter is greater than its length.
The development of the chest depends on the lifestyle of a person. Compare an athlete, swimmer, athlete with a non-athlete. It is easy to understand that the development of the chest, its mobility depends on the development of the muscles. Therefore, in adolescents of twelve to fifteen years old who go in for sports, the circumference of the chest is seven to eight centimeters larger than that of their peers who do not go in for sports.
Improper seating of students at a desk, squeezing the chest can lead to its deformation, which disrupts the development of the heart, large vessels and lungs.
Limbs. Due to the fact that the limbs are attached to a reliable support, they have mobility in all directions and are able to withstand heavy physical exertion.
Light bones - clavicles and shoulder blades, lying on the upper part of the chest, cover it like a belt. This is the handhold. The protrusions and ridges on the collarbone and shoulder blade are the site of muscle attachment. The greater the strength of these muscles, the more developed the bone processes and irregularities. In an athlete, a loader, the longitudinal ridge of the scapula is more developed than in a watchmaker or accountant. The clavicle is the bridge between the bones of the trunk and arms. The shoulder blade and collarbone create a reliable spring support for the hand.
The position of the shoulder blades and collarbones can be used to judge the position of the hands. Anatomists helped to restore the broken off hands of the ancient Greek statue of Venus de Milo, determining their position by the silhouettes of the shoulder blades and collarbones.
The pelvic bones are thick, wide and almost completely fused. In humans, the pelvis justifies its name - it, like a bowl, supports the internal organs from below. This is one of the typical features of the human skeleton. The massiveness of the pelvis is proportional to the massiveness of the bones of the legs, which bear the main load when a person moves, therefore the human pelvic skeleton can withstand a large load.
Leg and hand. With a vertical posture, a person’s hands do not carry a constant load as supports, they acquire lightness and variety of action, freedom of movement. The hand can perform hundreds of thousands of different motor operations. The legs carry the entire weight of the body. They are massive, have extremely strong bones and ligaments.
The head of the shoulder has no restriction in wide circular movements of the arms, such as when throwing a javelin. The head of the femur protrudes deeply into the deepening of the pelvis, which limits movement. The ligaments of this joint are the strongest and hold the weight of the body on the hips.
Exercise and training achieve greater freedom of movement of the legs, despite their massiveness. A convincing example of this can be ballet art, gymnastics, martial arts.
The tubular bones of the arms and legs have a huge margin of safety. It is interesting that the location of the openwork crossbars of the Eiffel Tower corresponds to the structure of the spongy substance of the heads of tubular bones, as if J. Eiffel designed the bones. The engineer used the same laws of construction that determine the structure of the bone, giving it lightness and strength. This is the reason for the similarity of the metal structure and the living bone structure.
The elbow joint provides complex and diverse movements of the hand in the working life of a person. Only he has the ability to rotate the forearm around its axis, with a characteristic movement of unwinding or twisting.
The knee joint directs the lower leg when walking, running, jumping. The knee ligaments in humans determine the strength of the support when the limb is straightened.
The hand begins with a group of bones of the wrist. These bones do not experience strong pressure, perform a similar function, so they are small, monotonous, and difficult to distinguish. It is interesting to mention that the great anatomist Andrei Vesalius could, blindfolded, identify each carpal bone and tell whether it belongs to the left or right hand.
The bones of the metacarpus are moderately mobile, they are located in the form of a fan and serve as a support for the fingers. Phalanges of fingers - 14. All fingers have three bones, except for the thumb - it has two bones. A person has a very mobile thumb. It can become at right angles to everyone else. Its metacarpal bone is able to oppose the rest of the bones of the hand.
The development of the thumb is associated with the labor movements of the hand. The Indians call the thumb "mother", the Javanese - "big brother". In ancient times, captives were cut off the thumb to humiliate their human dignity and make them unfit for participation in battles.
The brush makes the most subtle movements. In any working position of the hand, the hand retains complete freedom of movement.
The foot became more massive due to walking. The tarsal bones are very large and strong compared to the carpal bones. The largest of them are the talus and calcaneus. They can withstand significant weight of the body. In newborns, the movements of the foot and thumb are similar to those of monkeys. Strengthening the supporting role of the foot during walking led to the formation of its arch. When walking, standing, you can easily feel how the entire space between these points “hangs in the air”.
The vault, as is known in mechanics, withstands greater pressure than the platform. The arch of the foot provides the elasticity of the gait, eliminates pressure on the nerves and blood vessels. Its formation in the history of the origin of man is associated with upright walking and is a distinctive feature of man, acquired in the process of his historical development.
Two types of muscle tissue.
Smooth muscles. When we talked about muscles, we usually thought of skeletal muscles. But, besides them, in our body in the connective tissue there are smooth muscles in the form of single cells, in some places they are collected in bundles.
Many smooth muscles in the skin, they are located at the base of the hair bag. By contracting, these muscles raise the hair and squeeze out fat from the sebaceous gland.
In the eye around the pupil are smooth circular and radial muscles. They work all the time, imperceptibly for us, work: in bright light, the circular muscles constrict the pupil, and in the dark, the radial muscles contract and the pupil expands.
In the walls of all tubular organs - the respiratory tract, blood vessels, digestive tract, urethra, etc. - there is a layer of smooth muscles. Under the influence of nerve impulses, it is reduced. For example, reducing it in the windpipe delays the flow of air containing harmful impurities - dust, gases.
Due to the contraction and relaxation of the smooth cells of the walls of blood vessels, their lumen either narrows or expands, which contributes to the distribution of blood in the body. The smooth muscles of the esophagus, contracting, push a lump of food or a sip of water into the stomach.
Complex plexuses of smooth muscle cells are formed in organs with a wide cavity - in the stomach, bladder, uterus. The contraction of these cells causes compression and narrowing of the lumen of the organ. The strength of each cell contraction is negligible, since they are very small. However, the addition of the forces of entire beams can create a contraction of enormous force. Powerful contractions create a sensation of intense pain.
Muscles of the skeleton. Skeletal muscles carry out both static activity, fixing the body in a certain position, and dynamic, ensuring the movement of the body in space and its individual parts relative to each other. Both types of muscular activity closely interact, complementing each other: static activity provides a natural background for dynamic activity. As a rule, the position of the joint is changed with the help of several muscles of multidirectional, including opposite action. Complex joint movements are performed by coordinated, simultaneous or sequential contraction of non-directional muscles. Consistency (coordination) is especially necessary for the performance of motor acts in which many joints participate (for example, skiing, swimming).
Skeletal muscles are not only the executive motor apparatus, but also a kind of sensory organs. In the muscle fiber and tendons there are nerve endings - receptors that send impulses to cells at various levels of the central nervous system. As a result, a closed cycle is created: impulses from various formations of the central nervous system, going along the motor nerves, cause muscle contraction, and impulses sent by muscle receptors inform the central nervous system about each element of the system. The cyclic system of connections ensures the accuracy of movements and their coordination. Although the movement of skeletal muscles is controlled by various sections of the central nervous system, the leading role in ensuring interaction and setting the goal of a motor reaction belongs to the cerebral cortex. In the cerebral cortex, the motor and sensory zones of the representations form a single system, with each muscle group corresponding to a certain section of these zones. Such a relationship allows you to perform movements, attributing them to environmental factors acting on the body. Schematically, the control of arbitrary movements can be represented as follows. The tasks and purpose of a motor action are formed by thinking, which determines the direction of attention and efforts of a person. Thinking and emotions accumulate and direct these efforts. The mechanisms of higher nervous activity form the interaction of psychophysiological mechanisms of movement control at various levels. Based on the interaction of the musculoskeletal system, deployment and correction of motor activity are provided. Analyzers play an important role in the implementation of the motor reaction. The motor analyzer provides the dynamics and interconnection of muscle contractions, participates in the spatial and temporal organization of the motor act. The balance analyzer, or vestibular analyzer, interacts with the motor analyzer when the position of the body in space changes. Vision and hearing, actively perceiving information from the environment, are involved in spatial orientation and correction of motor reactions.
The name "muscle" comes from the word "musculis", which means "mouse".
This is due to the fact that anatomists, observing the contraction of skeletal muscles, noticed that they seem to run under the skin, like mice.
A muscle is made up of muscle plexuses. The length of muscle plexuses in humans reaches 12 cm. Each such plexus forms a separate muscle fiber.
Numerous rod-shaped nuclei are located under the shell of the muscle fiber. Along the entire length of the cell stretches several hundred of the thinnest filaments of the cytoplasm - myofibrils, capable of contracting. In turn, myofibrils are formed by 2.5 thousand protein filaments.
In myofibrils, light and dark discs alternate, and under a microscope, the muscle fiber looks transversely striated. Compare the function of skeletal and smooth muscles. It turns out that striated muscles cannot elongate as much as smooth ones. But skeletal muscles contract faster than the muscles of the internal organs. It is therefore not difficult to explain why a snail or an earthworm, devoid of striated muscles, moves slowly. The swiftness of the movements of the bee, lizard, eagle, horse, and man is ensured by the speed of contraction of the striated muscles.
Thickness muscle fibers different people is not the same. For those who go in for sports, muscle fibers develop well, their mass is large, which means that the contraction force is also large. The limited work of the muscles leads to a significant reduction in the thickness of the fibers and the mass of the muscles as a whole, and also entails a decrease in the force of contraction.
There are 656 skeletal muscles in the human body. Almost all muscles are paired. The position of the muscles, their shape, the method of attachment to the bones has been studied in detail by anatomy. The location and structure of the muscles is especially important for the surgeon to know. That is why the surgeon is first and foremost an anatomist, and anatomy and surgery are sisters. World merits in the development of these sciences belong to our domestic science, and above all to N.I. Pirogov.
Nerve connections in muscles. It is wrong to think that the muscle itself can contract. It would be difficult to imagine at least one coordinated movement if the muscles were uncontrollable. “Start up” the muscle in the course of nerve impulses. An average of 20 impulses per second enters one muscle. In each step, for example, up to 300 muscles take part, and many impulses coordinate their work.
The number of nerve endings in different muscles is not the same. There are relatively few of them in the thigh muscles, and the oculomotor muscles, which make subtle and precise movements all day long, are rich in motor nerve endings. The cortex of the hemisphere is unevenly connected with individual muscle groups. For example, large areas of the cortex are occupied by motor areas that control the muscles of the face, hand, lips, and foot, and relatively small areas are occupied by the muscles of the shoulder, thigh, and lower leg. The size of individual zones of the motor area of the cortex is proportional not to the mass of muscle tissue, but to the subtlety and complexity of the movements of the corresponding organs.
Each muscle has a double nerve subordination. One nerve sends impulses from the brain and spinal cord. They cause muscle contraction. Others, moving away from the nodes that lie on the sides of the spinal cord, regulate their nutrition.
The nerve signals that control muscle movement and nutrition are consistent with the nervous regulation of muscle blood supply. It turns out a single triple nervous control.
Muscles generate heat. Striated muscles are “engines” in which chemical energy is immediately converted into mechanical energy. The muscle uses 33% of the chemical energy for movement, which is released during the breakdown of animal starch - glycogen. 67% of the energy in the form of heat is transferred by the blood to other tissues and evenly warms the body. That is why in the cold a person tries to move more, as if warming himself up due to the energy that the muscles produce. Small involuntary muscle contractions cause tremors - the body increases the production of heat.
Strength and speed of muscle contraction. The strength of a muscle depends on the number of muscle fibers, on its cross-sectional area, the size of the surface of the bone to which it is attached, the angle of attachment and the frequency of nerve impulses. All these factors have been identified by special studies.
The strength of a person's muscles is determined by what load he can lift. Muscles outside the body develop strength several times greater than that which is manifested in human movements.
The working quality of a muscle is associated with its ability to suddenly change its elasticity. Muscle protein becomes very elastic during contraction. After contraction of the muscle, it again acquires its original state. Becoming elastic, the muscle holds the load, this manifests muscle strength. A human muscle for every square centimeter of section develops a force of up to 156.8 N.
One of the strongest muscles is the calf. It can lift a load of 130 kg. Every healthy person is able to "stand on tiptoe" on one leg and even lift an additional load. This load falls mainly on the calf muscle.
Being under the influence of constant nerve impulses, the muscles of our body are always tense, or, as they say, are in a state of tone - a long contraction. You can check the muscle tone for yourself: close your eyes with force, and you will feel the trembling of the contracted muscles in the eye area.
It is known that any muscle can contract with different strengths. For example, the same muscles are involved in lifting a small stone and a pound weight, but they expend different strength. The speed with which we can set our muscles in motion varies and depends on the training of the body. The violinist makes 10 movements per second, and the pianist - up to 40.
Fatigue and rest
Reasons for fatigue. Fatigue is an indicator that the body cannot work to its full potential. Why does muscle fatigue occur? For science, this question has long been unresolved. Various theories have been created.
Some scientists have suggested that the muscle is depleted from a lack of nutrients; Others said that her "suffocation" was coming, a lack of oxygen. It has been suggested that fatigue occurs due to poisoning, or clogging, of the muscle with toxic waste products. However, all these theories did not satisfactorily explain the causes of fatigue. As a result, there was an assumption that the cause of fatigue does not lie in the muscle. A hypothesis of nerve fatigue has been put forward. However, an outstanding Russian physiologist, one of the students of I. M. Sechenov, Professor N. E. Vvdensky proved by example that the nerve conductors are practically not fatiguable.
The path to unraveling the mystery of fatigue was opened by the Russian physiologist I. M. Sechenov. He developed the nervous theory of fatigue. He found that the right hand, after prolonged work, restored its working capacity, if during the period of its rest movements were made with the left hand. The nerve centers of the left hand, as it were, energized the tired nerve centers of the right hand. It turned out that fatigue is removed more quickly when the rest of the working hand is combined with the work of the other hand than with complete rest. With these experiments, I. M. Sechenov outlined ways to relieve fatigue and methods for their reasonable organization of rest, thereby realizing his noble desire to facilitate human work.
Statics and dynamics of the human body
Equilibrium conditions. Every body has mass and has a center of gravity. A plumb line passing through the center of gravity (line of gravity) always falls onto the support. The lower the center of gravity and the wider the support, the more stable the balance. So, when standing, the center of gravity is placed approximately at the level of the second sacral vertebra. The line of gravity is between both feet, inside the support area.
The stability of the body increases significantly if you spread your legs: the area of \u200b\u200bsupport increases. When the legs approach each other, the area of support decreases, and therefore stability also decreases. The stability of a person standing on one leg is even less.
Our body has great mobility, and the center of gravity is constantly shifting. For example, when carrying a bucket of water in one hand, for stability, you lean in the opposite direction, while extending the other arm almost horizontally. If you carry a heavy object on your back, the body leans forward. In all these cases, the line of gravity approaches the edge of the support, so the balance of the body is stable. If the projection of the center of gravity of the body goes beyond the area of support, the body will fall. Its stability is ensured by a shift in the center of gravity, corresponding to a change in the position of the body. To create a counterweight, the body leans in the direction opposite to the load. The line of gravity remains inside the area of support.
By performing various gymnastic exercises, you can determine how balance and stability are maintained if the center of gravity goes beyond the fulcrum.
Rope walkers, for greater stability, take a pole in their hands, which they tilt to one side or the other. Balancing they move the center of gravity to a limited support.
Sports are for everyone
Muscle training. Active physical activity is one of the prerequisites for the harmonious development of a person.
Constant exercises lengthen the muscles, develop their ability to stretch better. During training, muscle mass increases, muscles become stronger, nerve impulses cause muscle contraction of great strength.
Muscle strength and bone strength are interrelated. When playing sports, the bones become thicker, and accordingly developed muscles have sufficient support. The entire skeleton becomes stronger and more resistant to stress and injury. A good physical load is a necessary condition for the normal growth and development of the body. A sedentary lifestyle is harmful to health. Lack of movement is the cause of flabbiness and muscle weakness. Physical exercises, work, games develop working capacity, endurance, strength, dexterity and speed.
Labor and sport. Movements in work and sports are forms of muscular activity. Work and sport are interconnected and complement each other.
Two students came to the workshop, stood at the workbench for the first time. One is into sports, the other is not. It is easy to see how quickly an athlete learns labor skills.
Sport develops important motor qualities - agility, speed, strength, endurance.
These qualities are improved in work.
Labor and physical education help each other. They favor mental work. When moving, the brain receives an abundance of nerve signals from the muscles that maintain its normal state and develop. Overcoming fatigue during physical labor increases efficiency during mental activities.
Anyone can become an athlete. Do I need to have any natural qualities to become an athlete? There can be only one answer: no. Diligence and systematic training ensure the achievement of high sports results. Sometimes it is recommended to take into account the general features of the physique for the choice of a particular sport.
Yes, and it's not always necessary. Some athletes have achieved first-class results in sports for which, it would seem, they have no data. Vitaly Ushakov, despite the small capacity of the lungs before playing sports, became a first-class swimmer and gave better results than some other athletes with "natural buoyancy".
The famous wrestler I. M. Poddubny wrote that wrestlers are not born, wrestling develops a person and he becomes a powerful strongman from an ordinary kid.
Desire and perseverance, training and a thoughtful attitude to physical activities do wonders. Even sick, physically weak and pampered people can become excellent athletes. For example, the European champion in race walking A. I. Egorov suffered from rickets in childhood, and did not walk until he was 5 years old. Under the supervision of a doctor, he began to play sports and achieved high rates.
Great people about the benefits of exercise.
Gymnastics as a means of physical education originated in ancient China and India, but especially developed in ancient Greece. The Greeks went in for sports naked under the rays of the southern sun. From here, in fact, the word “gymnastics” comes from: translated from ancient Greek “gymnos” means “naked”.
Even the great thinkers of antiquity Plato, Aristotle, Socrates noted the influence of movements on the body. They themselves were engaged in gymnastics until a very old age.
M. V. Lomonosov was the first to raise his voice in defense of the health of the Russian people. He himself was distinguished by great physical strength and athletic build. Lomonosov considered it necessary "to try in every possible way to be in the movement of the body." He thought to introduce the Olympic Games in Russia. The great scientist spoke about the benefits of motor activity after intense mental work. “Movement,” he said, “can serve instead of medicine.”
AI Radishchev deeply believed that physical education can "strengthen the body, and with it the spirit."
A. V. Suvorov introduced, and did military gymnastics himself, demanded training and hardening of troops. “My offspring,” said the great commander, “please take my example.”
Contemporaries of A. S. Pushkin wrote about him that he was of the strongest build, muscular, flexible, and this was facilitated by gymnastics.
L. N. Tolstoy was fond of cycling and horseback riding. At the age of 82, he made horseback rides of 20 or more miles a day. He loved to mow, dig, saw. At the age of 70, Tolstoy won in skating the youth who were visiting Yasnaya Polyana. He wrote: “With assiduous mental work without movement and bodily labor, there is real grief. I don’t look like, I don’t work with my legs and arms for at least one day, in the evening I’m no longer fit: neither to read, nor write, nor even listen carefully to others, my head is spinning, and there are some stars in my eyes, and the night is spent without sleep."
Maxim Gorky was fond of rowing, swimming, playing gorodki, in winter he went skiing and skating.
I. P. Pavlov went in for sports until a ripe old age and loved physical labor. For many years he led the gymnastic circle of doctors in St. Petersburg.
Conclusion
In the legends, the Russian people endowed their heroes with extraordinary strength, glorified their heroic deeds in labor and in defending the Motherland from enemies. Work and love for the native land in the minds of the people are inseparable from each other.
In epics and legends, the features of our people are displayed - diligence, courage, mighty strength. The Arab writer of the 11th century, Abubekri, wrote that the Slavs are such a powerful people that if they were not divided into many clans, no one would be able to resist them.
The struggle with the harsh nature, external enemies developed in them qualities worthy of admiration. Strong, freedom-loving, hardened, not afraid of either cold or heat, not spoiled by excesses and luxury - such were our ancestors even according to the description of their enemies.
List of used literature.
- www.referat
"Reserves of the body" B. P. Nikitin, L. A. Nikitina. 1990
"A Reading Book on Human Anatomy, Physiology and Hygiene". I. D. Zverev, 1983
"Russian power". Valentin Lavrov. 1991
"Secrets of Athleticism". Yuri Shaposhnikov. 1991
"Biology Man Grade 9". A. S. Batuev. 1997
In the musculoskeletal system, two parts are distinguished: passive and active. The passive part is a skeleton formed by bones and their joints. The active part is represented by skeletal muscles formed by striated muscle tissue, the diaphragm, and the walls of internal organs.
Human skeleton
The skeleton performs two main functions: mechanical and biological.
Mechanical function includes:
Support function - the bones, together with their joints, constitute the support of the body, to which soft tissues and organs are attached;
The function of movement (albeit indirectly, since the skeleton serves to attach skeletal muscles);
Spring function - due to articular cartilage and other structures of the skeleton (arch of the foot, curves of the spine), softening shocks and tremors;
Protective function - the formation of bone formations to protect important organs: the brain and spinal cord; heart, lungs. The genital organs are located in the pelvic cavity. The bones themselves contain red bone marrow.
Under biological function understand:
Hematopoietic function - red bone marrow, located in the bones, is a source of blood cells;
The storage function - bones serve as a depot for many inorganic compounds: phosphorus, calcium, iron, magnesium, and therefore participate in maintaining a constant mineral composition of the internal environment of the body.
The human skeleton is formed different kind bones. According to the shape and structure of the bones are divided into:
Tubular bones (long and short) are the bones of the skeleton of free limbs.
Spongy bones: long - ribs and sternum; short - vertebrae, bones of the wrist, tarsus;
Flat bones - bones of the roof of the skull, scapula, pelvic bone, built from a spongy substance surrounded by a plate of compact substance;
Mixed bones - temporal and base of the skull.
The bones of the skeleton can be connected in two ways.
The first way is to connect the bones when there is no gap between them. Such connections are called continuous. Continuous connections can be formed by connective tissue (for example, ligaments between the vertebral arches), cartilage tissue (connection of the ribs to the sternum) and bone fusion (the bones of the skull grow together with the formation of a seam, and the pelvic bones - without a seam).
The second connection method is called intermittent connection - a gap remains between the bones. Such connections are called joints. Depending on the shape of the articular surfaces and the degree of joint mobility (the number of axes along which movement occurs in the joint), the following types of joints are distinguished
Uniaxial flat joints between the articular processes of the vertebrae
Cylindrical Articulation between the ulna and radius
Block-shaped interphalangeal joints
Biaxial Saddle Carpal joint
Ellipsoidal Between the occipital bone and the first cervical vertebra; radiocarpal
Triaxial Spherical Shoulder
Walnut
The connection of bones can also be divided according to the degree of mobility of the joints. So, the joints will refer to mobile joints, and the connection by fusion of bones - to fixed joints (bones of the skull, connection of the bones of the pelvis with the sacrum).
Connections of bones with the help of cartilaginous and dense connective tissue are mobile joints (connection of the bodies of the cervical, thoracic, lumbar vertebrae).
The human skeleton consists of the skeleton of the head, or skull, the skeleton of the trunk, which is subdivided into the spine and chest, consisting of the ribs and sternum, and the skeleton of the limbs. The limb skeleton is subdivided into the free limb skeleton and the limb girdle skeleton.
The active part of the musculoskeletal system is represented by muscles. The muscles distinguish between the central part, or the contractile (abdomen), built from striated muscle tissue, and the end parts, or irreducible, tendons formed by dense fibrous connective tissue. With the help of tendons, muscles are attached to the bones of the skeleton, therefore they are called skeletal. The shape of the muscles depends on the location of the muscle fibers relative to the axis of the tendon.
According to the function performed, respiratory, chewing, facial muscles are distinguished, and according to the action on the joints: flexors, extensors, abductors, adductors, rotational, constrictors. If two muscles in a joint perform the same action, such muscles are called synergists, if the muscles perform opposite actions, they are called antagonists.
