Introduced the concept of reflex as an automatic way of responding. Reflex. Definition. Types of reflexes. A simple definition of the concept "reflex"

• 1.1The role of physiology in the materialistic understanding of the essence of life. The significance of the works of I.M. Sechenov and I.P. Pavlov in the creation of the materialistic foundations of physiology.
• 2.2 Stages of development of physiology. Analytical and systematic approach to the study of body functions. Method of acute and chronic experiment.
• 3.3 Definition of physiology as a science. Physiology as the scientific basis for diagnosing health and predicting the functional state and performance of a person.
• 4.4 Determination of physiological function. Examples of physiological functions of cells, tissues, organs and systems of the body. Adaptation as the main function of the body.
• 5.5 The concept of regulation of physiological functions. Mechanisms and methods of regulation. The concept of self-regulation.
• 6.6Basic principles of reflex activity of the nervous system (determinism, synthesis analysis, unity of structure and function, self-regulation)
• 7.7 Definition of reflex. Classification of reflexes. Modern structure of the reflex arc. Feedback, its meaning.
• 8.8 Humoral connections in the body. Characteristics and classification of physiologically and biologically active substances. The relationship between nervous and humoral regulatory mechanisms.
• 9.9 Teachings of P.K. Anokhin about functional systems and self-regulation of functions. Nodal mechanisms of functional systems, general diagram
• 10.10Self-regulation of the constancy of the internal environment of the body. The concept of homeostasis and homeokinesis.
• 11.11 Age-related features of the formation and regulation of physiological functions. Systemogenesis.
• 12.1 Irritability and excitability as the basis of tissue response to irritation. The concept of a stimulus, types of stimuli, characteristics. The concept of irritation threshold.
• 13.2 Laws of irritation of excitable tissues: the value of the strength of the stimulus, the frequency of the stimulus, its duration, the steepness of its increase.
• 14.3 Modern ideas about the structure and function of membranes. Membrane ion channels. Cell ion gradients, mechanisms of origin.
• 15.4 Membrane potential, theory of its origin.
• 16.5. Action potential, its phases. Dynamics of membrane permeability in different phases of the action potential.
• 17.6 Excitability, methods for its assessment. Changes in excitability under the influence of direct current (electroton, cathodic depression, accommodation).
• 18.7 Correlations between the phases of changes in excitability during excitation and the phases of the action potential.
• 19.8 Structure and classification of synapses. Mechanism of signal transmission in synapses (electrical and chemical) Ionic mechanisms of postsynaptic potentials, their types.
• 20.10 Definition of mediators and synoptic receptors, their classification and role in conducting signals in excitatory and inhibitory synapses.
• 21Definition of transmitters and synaptic receptors, their classification and role in the conduction of signals in excitatory and inhibitory synapses.
• 22.11 Physical and physiological properties of muscles. Types of muscle contractions. Strength and muscle function. Law of force.
• 23.12 Single contraction and its phases. Tetanus, factors influencing its size. The concept of optimum and pessimum.
• 24.13 Motor units, their classification. Role in the formation of dynamic and static contractions of skeletal muscles in natural conditions.
• 25.14 Modern theory of muscle contraction and relaxation.
• 26.16 Features of the structure and functioning of smooth muscles
• 27.17 Laws of conduction of excitation through nerves. The mechanism of nerve impulse transmission along unmyelinated and myelinated nerve fibers.
• 28.17 Receptors of sensory organs, concept, classification, basic properties and features. Excitation mechanism. The concept of functional mobility.
• 29.1 Neuron as a structural and functional unit in the central nervous system. Classification of neurons according to structural and functional characteristics. The mechanism of excitation penetration in a neuron. Integrative function of a neuron.
• Question 30.2 Definition of the nerve center (classical and modern). Properties of nerve centers determined by their structural links (irradiation, convergence, aftereffect of excitation)
• Question 32.4 Inhibition in the central nervous system (I.M. Sechenov). Modern ideas about the main types of central inhibition, postsynaptic, presynaptic and their mechanisms.
• Question 33.5 Definition of coordination in the central nervous system. Basic principles of the coordination activity of the central nervous system: reciprocity, common “final” path, dominant, temporary connection, feedback.
• Question 35.7 The medulla oblongata and the pons, the participation of their centers in the processes of self-regulation of functions. Reticular formation of the brainstem and its descending influence on the reflex activity of the spinal cord.
• Question 36.8 Physiology of the midbrain, its reflex activity and participation in the processes of self-regulation of functions.
• 37.9 The role of the midbrain and medulla oblongata in the regulation of muscle tone. Decerebrate rigidity and the mechanism of its occurrence (gamma rigidity).
• Question 38.10 Static and statokinetic reflexes. Self-regulatory mechanisms maintaining body balance.
• Question 39.11 Physiology of the cerebellum, its influence on motor (alpha-regidity) and autonomic functions of the body.
• 40.12 Ascending activating and inhibitory influences of the reticular formation of the brain stem on the cerebral cortex. The role of the Russian Federation in the formation of the integrity of the body.
• Question 41.13 Hypothalamus, characteristics of the main nuclear groups. The role of the hypothalamus in the integration of autonomic, somatic and endocrine functions, in the formation of emotions, motivation, stress.
• Question 42.14 The limbic system of the brain, its role in the formation of motivation, emotions, self-regulation of autonomic functions.
• Question 43.15 Thalamus, functional characteristics and features of nuclear groups of the thalamus.
• 44.16. The role of the basal ganglia in the formation of muscle tone and complex motor acts.
• 45.17 Structural and functional organization of the cerebral cortex, projection and association zones. Plasticity of cortex functions.
• 46.18 Functional asymmetry of the BP cortex, dominance of the hemispheres and its role in the implementation of higher mental functions (speech, thinking, etc.)
• 47.19 Structural and functional features of the autonomic nervous system. Autonomic neurotransmitters, main types of receptor substances.
• 48.20 Divisions of the autonomic nervous system, relative physiological antagonism and biological synergism of their effects on innervated organs.
• 49.21 Regulation of autonomic functions (kbp, limbic system, hypothalamus) of the body. Their role in the autonomic support of goal-directed behavior.
• 50.1 Determination of hormones, their formation and secretion. Effect on cells and tissues. Classification of hormones according to various criteria.
• 51.2 Hypothalamic-pituitary system, its functional connections. Trans and para pituitary regulation of the endocrine glands. The mechanism of self-regulation in the activity of the endocrine glands.
• 52.3 Pituitary hormones and their participation in the regulation of endocrine organs and body functions.
• 53.4 Physiology of the thyroid and parathyroid glands. Neurohumoral mechanisms regulating their functions.
• 55.6 Physiology of the adrenal glands. The role of hormones of the cortex and medulla in the regulation of body functions.
• 56.7 Sex glands. Male and female sex hormones and their physiological role in the formation of sex and regulation of reproductive processes.
• 57.1 Concept of the blood system (Lang), its properties, composition, functions. Composition of blood. Basic physiological blood constants and mechanisms of their maintenance.
• 58.2 Composition of blood plasma. Blood osmotic pressure fs, ensuring the constancy of blood osmotic pressure.
• 59.3 Blood plasma proteins, their characteristics and functional significance. Oncotic pressure in blood plasma.
• 60.4 Blood pH, physiological mechanisms that maintain the constancy of acid-base balance.
• 61.5 Red blood cells and their functions. Counting methods. Types of hemoglobin, its compounds, their physiological significance. Hemolysis.
• 62.6 Regulation of erythro and leukopoiesis.
• 63.7 Concept of hemostasis. The process of blood coagulation and its phases. Factors that accelerate and slow down blood clotting.
• 64.8 Vascular-platelet hemostasis.
• 65.9 Coagulation, anticoagulation and fibrinolytic blood systems as the main components of the apparatus of a functional system for maintaining a fluid state of blood
• 66.10 Concept of blood groups. Avo and Rh factor systems. Determination of blood group. Rules for blood transfusion.
• 67.11 Lymph, its composition, functions. Non-vascular liquid media, their role in the body. Exchange of water between blood and tissues.
• 68.12 Leukocytes and their types. Counting methods. Leukocyte formula. Functions of leukocytes.
• 69.13 Platelets, quantity and functions in the body.
• 70.1 The importance of blood circulation for the body.
• 71.2 Heart, the significance of its chambers and valve apparatus. Cardiocycle and its structure.
• 73. PD of cardiomyocytes
• 74. The ratio of excitation, excitability and contraction of the cardiomyocyte in various phases of the cardiac cycle. Extrasystoles
• 75.6 Intracardiac and extracardiac factors involved in the regulation of cardiac activity, their physiological mechanisms.
• Extracardiac
• Intracardiac
• 76. Reflex regulation of heart activity. Reflexogenic zones of the heart and blood vessels. Intersystem cardiac reflexes.
• 77.8 Auscultation of the heart. Heart sounds, their origin, listening locations.
• 78. Basic laws of hemodynamics. Linear and volumetric velocity of blood flow in various parts of the circulatory system.
• 79.10 Functional classification of blood vessels.
• 80. Blood pressure in various parts of the circulatory system. Factors that determine its magnitude. Types of blood pressure. The concept of mean arterial pressure.
• 81.12 Arterial and venous pulse, origin.
• 82.13 Physiological features of blood circulation in the myocardium, kidneys, lungs, brain.
• 83.14 The concept of basal vascular tone.
• 84. Reflex regulation of systemic blood pressure. The importance of vascular reflexogenic zones. Vasomotor center, its characteristics.
• 85.16 Capillary blood flow and its features. Microcirculation.
• 89. Bloody and bloodless methods for determining blood pressure.
• 91. Comparison of ECG and FCG.
• 92.1 Breathing, its essence and main stages. Mechanisms of external respiration. Biomechanics of inhalation and exhalation. Pressure in the pleural cavity, its origin and role in the ventilation mechanism.
• 93.2Gas exchange in the lungs. Partial pressure of gases (oxygen and carbon dioxide) in the alveolar air and gas tension in the blood. Methods for analyzing blood and air gases.
• 94. Transport of oxygen in the blood. Dissociation curve of oxyhemoglobin. The influence of various factors on the affinity of hemoglobin for oxygen. Oxygen capacity of the blood. Oxygemometry and oxygemography.
• 98.7 Methods for determining pulmonary volumes and capacities. Spirometry, spirography, pneumotachometry.
• 99Respiratory center. Modern representation of its structure and localization. Autonomy of the respiratory center.
• 101 Self-regulation of the respiratory cycle, mechanisms of change of respiratory phases. The role of peripheral and central mechanisms.
• 102 Humoral influences on respiration, the role of carbon dioxide and pH levels. The mechanism of the first breath of a newborn. The concept of respiratory analeptics.
• 103.12 Breathing under conditions of low and high barometric pressure and when the gas environment changes.
• 104. Fs ensures the constancy of the blood gas composition. Analysis of its central and peripheral components
• 105.1. Digestion, its meaning. Functions of the digestive tract. Research in the field of digestion by P. Pavlov. Methods for studying the functions of the gastrointestinal tract in animals and humans.
• 106.2. Physiological bases of hunger and satiety.
• 107.3. Principles of regulation of the digestive system. The role of reflex, humoral and local regulatory mechanisms. Gastrointestinal hormones
• 108.4. Digestion in the oral cavity. Self-regulation of the chewing act. Composition and physiological role of saliva. Regulation of salivation. The structure of the reflex arc of salivation.
• 109.5. Swallowing is the phase of self-regulation of this act. Functional features of the esophagus.
• 110.6. Digestion in the stomach. Composition and properties of gastric juice. Regulation of gastric secretion. Phases of gastric juice separation.
• 111.7. Digestion in the duodenum. Exocrine activity of the pancreas. Composition and properties of pancreatic juice. Regulation of pancreatic secretion.
• 112.8. The role of the liver in digestion: barrier and bile-forming functions. Regulation of the formation and secretion of bile into the duodenum.
• 113.9. Motor activity of the small intestine and its regulation.
• 114.9. Cavity and parietal digestion in the small intestine.
• 115.10. Features of digestion in the large intestine, colon motility.
• 116 Fs, ensuring constant power supply. The thing is in the blood. Analysis of central and peripheral components.
• 117) The concept of metabolism in the body. Processes of assimilation and dissimilation. Plastic energetic role of nutrients.
• 118) Methods for determining energy consumption. Direct and indirect calorimetry. Determination of the respiratory coefficient, its significance for determining energy consumption.
• 119) Basic metabolism, its significance for the clinic. Conditions for measuring basal metabolism. Factors influencing the basal metabolic rate.
• 120) Energy balance of the body. Work exchange. Energy expenditure of the body during different types of labor.
• 121) Physiological nutritional standards depending on age, type of work and state of the body. Principles of compiling food rations.
• 122. Constancy of the temperature of the internal environment of the body as a condition for the normal course of metabolic processes….
• 123) Human body temperature and its daily fluctuations. Temperature of various areas of the skin and internal organs. Nervous and humoral mechanisms of thermoregulation.
• 125) Heat dissipation. Methods of heat transfer from the surface of the body. Physiological mechanisms of heat transfer and their regulation
• 126) The excretory system, its main organs and their participation in maintaining the most important constants of the internal environment of the body.
• 127) Nephron as a structural and functional unit of the kidney, structure, blood supply. The mechanism of formation of primary urine, its quantity and composition.
• 128) Formation of final urine, its composition. Reabsorption in tubules, mechanisms of its regulation. Processes of secretion and excretion in the renal tubules.
• 129) Regulation of kidney activity. The role of nervous and humoral factors.
• 130. Methods for assessing the amount of filtration, reabsorption and secretion of the kidneys. The concept of purification coefficient.
• 131.1 Pavlov's teaching on analyzers. Concept of sensory systems.
• 132.3 Conductor department of analyzers. The role and participation of switching nuclei and reticular formation in the conduction and processing of afferent excitations
• 133.4 Cortical section of analyzers. Processes of higher cortical analysis of afferent excitations. Interaction of analyzers.
• 134.5 Adaptation of the analyzer, its peripheral and central mechanisms.
• 135.6 Characteristics of the visual analyzer. Receptor apparatus. Photochemical processes in the retina under the influence of light. Perception of light.
• 136.7 Modern ideas about the perception of light. Methods for studying the function of the visual analyzer. The main forms of color vision impairment.
• 137.8 Hearing analyzer. Sound-collecting and sound-conducting apparatus. Receptor section of the auditory analyzer. Mechanism of the occurrence of receptor potential in the hair cells of the spinal organ.
• 138.9. Theory of sound perception. Methods for studying the auditory analyzer.
• 140.11 Physiology of the taste analyzer. Receptor, conduction and cortical sections. Classification of taste sensations. Methods for studying the taste analyzer.
• 141.12 Pain and its biological significance. The concept of nociception and central mechanisms of pain. Actinociceptive system. Neurochemical mechanisms of actinociception.
• 142. The concept of the antipain (antinociceptive) system. Neurochemical mechanisms of antinociception, rolendorphins and exorphins.
• 143. Conditioned reflex as a form of adaptation of animals and humans to changing living conditions….
• Rules for developing conditioned reflexes
• Classification of conditioned reflexes
• 144.2 Physiological mechanisms of the formation of conditioned reflexes. Classical and modern ideas about the formation of temporary connections.

• Reflex- the main form of nervous activity. The body's response to stimulation from the external or internal environment, carried out with the participation of the central nervous system, is called reflex.

  Based on a number of characteristics, reflexes can be divided into groups

  By type of education: conditioned and unconditioned reflexes

  By type of receptor: exteroceptive (skin, visual, auditory, olfactory), interoceptive (from receptors of internal organs) and proprioceptive (from receptors of muscles, tendons, joints)

  By effector: somatic or motor (skeletal muscle reflexes), for example flexor, extensor, locomotor, statokinetic, etc.; vegetative internal organs - digestive, cardiovascular, excretory, secretory, etc.

  According to biological significance: defensive, or protective, digestive, sexual, orientation.

  According to the degree of complexity of the neural organization of reflex arcs, a distinction is made between monosynaptic, whose arcs consist of afferent and efferent neurons (for example, knee), and polysynaptic, whose arcs also contain 1 or more intermediate neurons and have 2 or several synaptic switches (for example, flexor).

  According to the nature of the influences on the activity of the effector: excitatory - causing and enhancing (facilitating) its activity, inhibitory - weakening and suppressing it (for example, a reflex increase in heart rate by the sympathetic nerve and a decrease in it or cardiac arrest by the vagus).

  Based on the anatomical location of the central part of the reflex arcs, spinal reflexes and cerebral reflexes are distinguished. Neurons located in the spinal cord are involved in the implementation of spinal reflexes. An example of the simplest spinal reflex is the withdrawal of a hand from a sharp pin. Brain reflexes are carried out with the participation of brain neurons. Among them there are bulbar, carried out with the participation of neurons of the medulla oblongata; mesencephalic - with the participation of midbrain neurons; cortical - with the participation of neurons in the cerebral cortex.

  Unconditioned reflexes- hereditarily transmitted (congenital) reactions of the body, inherent in the entire species. They perform a protective function, as well as the function of maintaining homeostasis (adaptation to environmental conditions).

  Unconditioned reflexes are an inherited, unchangeable reaction of the body to external and internal signals, regardless of the conditions for the occurrence and course of reactions. Unconditioned reflexes ensure the body's adaptation to constant environmental conditions. The main types of unconditioned reflexes: food, protective, orientation, sexual.

  An example of a defensive reflex is the reflexive withdrawal of the hand from a hot object. Homeostasis is maintained, for example, by a reflex increase in breathing when there is an excess of carbon dioxide in the blood. Almost every part of the body and every organ is involved in reflex reactions.

  The simplest neural networks, or arcs (according to Sherrington), involved in unconditioned reflexes, are closed in the segmental apparatus of the spinal cord, but can also be closed higher (for example, in the subcortical ganglia or in the cortex). Other parts of the nervous system are also involved in reflexes: the brain stem, cerebellum, and cerebral cortex.

  The arcs of unconditioned reflexes are formed at the time of birth and remain throughout life. However, they can change under the influence of illness. Many unconditioned reflexes appear only at a certain age; Thus, the grasping reflex characteristic of newborns fades away at the age of 3-4 months.

  Conditioned reflexes arise during individual development and accumulation of new skills. The development of new temporary connections between neurons depends on environmental conditions. Conditioned reflexes are formed on the basis of unconditioned ones with the participation of higher parts of the brain.

  The development of the doctrine of conditioned reflexes is associated primarily with the name of I. P. Pavlov. He showed that a new stimulus can initiate a reflex response if it is presented for some time together with an unconditioned stimulus. For example, if you let a dog smell meat, it will secrete gastric juice (this is an unconditioned reflex). If you ring a bell at the same time as the meat, the dog’s nervous system associates this sound with food, and gastric juice will be released in response to the bell, even if the meat is not presented. Conditioned reflexes underlie acquired behavior

  Reflex arc(nerve arc) - the path traversed by nerve impulses during the implementation of a reflex

  The reflex arc consists of six components: receptors, afferent pathway, reflex center, efferent pathway, effector (working organ), feedback.

  Reflex arcs can be of two types:

  1) simple - monosynaptic reflex arcs (reflex arc of the tendon reflex), consisting of 2 neurons (receptor (afferent) and effector), there is 1 synapse between them;

  2) complex – polysynaptic reflex arcs. They consist of 3 neurons (there may be more) - a receptor, one or more intercalary and an effector.

  The feedback loop establishes a connection between the realized result of the reflex response and the nerve center that issues executive commands. With the help of this component, the open reflex arc is transformed into a closed one.

  Rice. 5. Reflex arc of the knee reflex:

  1 - receptor apparatus; 2 - sensory nerve fiber; 3 - intervertebral node; 4 - sensory neuron of the spinal cord; 5 - motor neuron of the spinal cord; 6 - motor fiber of the nerve

  "

Historical information

The assumption about the reflex nature of the activity of the higher parts of the brain was first developed by the scientist-physiologist I.M. Sechenov. Before him, physiologists and neurologists did not dare to raise the question of the possibility of a physiological analysis of mental processes, which were left to psychology to solve.

Further, the ideas of I.M. Sechenov were developed in the works of I.P. Pavlov, who discovered the ways of objective experimental research of the functions of the cortex, developed a method for developing conditioned reflexes and created the doctrine of higher nervous activity. Pavlov in his works introduced the division of reflexes into unconditioned, which are carried out by innate, hereditarily fixed nerve pathways, and conditioned, which, according to Pavlov’s views, are carried out through nerve connections formed in the process of individual life of a person or animal.

Charles S. Sherrington (Nobel Prize in Physiology or Medicine, 1932) made a great contribution to the formation of the doctrine of reflexes. He discovered coordination, mutual inhibition and facilitation of reflexes.

The meaning of the doctrine of reflexes

The doctrine of reflexes has given a lot to understanding the very essence of nervous activity. However, the reflex principle itself could not explain many forms of goal-directed behavior. Currently, the concept of reflex mechanisms has been supplemented by the idea of ​​the role of needs in the organization of behavior; it has become generally accepted that the behavior of animal organisms, including humans, is active in nature and is determined not so much by the irritations that arise, but by the plans and intentions that arise under influenced by certain needs. These new ideas were expressed in the physiological concepts of the “functional system” by P.K. Anokhin or “physiological activity” by N.A. Bernstein. The essence of these concepts boils down to the fact that the brain can not only adequately respond to external stimuli, but also foresee the future, actively make plans for its behavior and implement them in action. The idea of ​​an “acceptor of action”, or a “model of the required future”, allows us to talk about “ahead of reality”.

General mechanism of reflex formation

Neurons and the pathways of nerve impulses during a reflex act form a so-called reflex arc:

Stimulus - receptor-affector - CNS neuron - effector - reaction.

Classification

Based on a number of characteristics, reflexes can be divided into groups

• By type of education: conditioned and unconditioned reflexes
• By type of receptor: exteroceptive (skin, visual, auditory, olfactory), interoceptive (from receptors of internal organs) and proprioceptive (from receptors of muscles, tendons, joints)
• By effector: somatic or motor (skeletal muscle reflexes), for example flexor, extensor, locomotor, statokinetic, etc.; vegetative internal organs - digestive, cardiovascular, excretory, secretory, etc.
• According to biological significance: defensive, or protective, digestive, sexual, orientation.
• According to the degree of complexity of the neural organization of reflex arcs, a distinction is made between monosynaptic, whose arcs consist of afferent and efferent neurons (for example, knee), and polysynaptic, whose arcs also contain 1 or more intermediate neurons and have 2 or several synaptic switches (for example, flexor).
• According to the nature of the influences on the activity of the effector: excitatory - causing and enhancing (facilitating) its activity, inhibitory - weakening and suppressing it (for example, a reflex increase in heart rate by the sympathetic nerve and a decrease in it or cardiac arrest by the vagus).
• Based on the anatomical location of the central part of the reflex arcs, spinal reflexes and cerebral reflexes are distinguished. Neurons located in the spinal cord are involved in the implementation of spinal reflexes. An example of the simplest spinal reflex is the withdrawal of a hand from a sharp pin. Brain reflexes are carried out with the participation of brain neurons. Among them there are bulbar, carried out with the participation of neurons of the medulla oblongata; mesencephalic - with the participation of midbrain neurons; cortical - with the participation of neurons in the cerebral cortex.

Unconditional

Unconditioned reflexes are hereditarily transmitted (innate) reactions of the body, inherent to the entire species. They perform a protective function, as well as the function of maintaining homeostasis (adaptation to environmental conditions).

Unconditioned reflexes are inherited, unchangeable reactions of the body to certain influences of the external or internal environment, regardless of the conditions for the occurrence and course of reactions. Unconditioned reflexes ensure the body's adaptation to constant environmental conditions. The main types of unconditioned reflexes: food, protective, orientation, sexual.

An example of a defensive reflex is the reflexive withdrawal of the hand from a hot object. Homeostasis is maintained, for example, by a reflex increase in breathing when there is an excess of carbon dioxide in the blood. Almost every part of the body and every organ is involved in reflex reactions.

Pathological reflexes

Pathological reflexes are a neurological term that refers to reflex reactions that are unusual for a healthy adult. In some cases, they are characteristic of earlier stages of phylo- or ontogenesis.

There is an opinion that mental dependence on something is caused by the formation of a conditioned reflex. For example, mental dependence on drugs is due to the fact that taking a certain substance is associated with a pleasant state (a conditioned reflex is formed that persists for almost the entire life).

see also

Notes

Literature

• Skoromets A. A., Skoromets A. P., Skoromets T. A. Propaedeutics of clinical neurology. St. Petersburg: Politekhnika, 2004
• Chief editor member Academy of Medical Sciences of the USSR Kositsky G.I., “Human Physiology.” Ed. "Medicine", 1985.
• Dictionary of physiological terms / resp. ed. Gazenko O.G.. - M.: “Science”, 1987. - 32,000 copies.
• Fundamental and clinical physiology: Textbook for students of higher educational institutions / ed. Kamkin A.G., Kamensky A.A.. - M.: Publishing Center "Academy", 2004. - 1072 p. - 5,000 copies. -

Answers:

1 . reflex.

A reflex is the body's response to irritation of sensitive formations - receptors (to irritations from the external and internal environment), carried out with the participation of the nervous system.

Irritations are perceived by the nerve endings of sensitive receptors in the form of nerve impulses.

The path along which nerve impulses travel during a reflex is called a reflex arc.

Reflex is the main form of activity of the nervous system. In the central nervous system, reflex activity is caused by the interaction of excitation and inhibition processes.

Unconditioned and conditioned reflexes (types of reflexes).

The outstanding Russian physiologist I.P. Pavlov studied reflexes and divided reflexes into unconditioned and conditioned.

Reflexes :

ü Unconditioned - innate reflexes, inherited by the body; these are constant reactions of the body to certain external stimuli (eye blinking reflex, constriction of the pupils when exposed to strong light);

ü Conditioned - acquired reflexes that arise in certain conditions; These are individual reflexes, they are acquired and formed throughout life, but they are based on unconditioned reflexes (for example, salivation to the smell of food).

The role of reflexes in human life:

Reflexes are acts of conscious and unconscious activity.

1) Unconditioned reflexes ensure the body’s adaptation to constant environmental conditions.

2) Unconditioned reflexes provide nutritional and protective processes.

3) Conditioned reflexes shape human behavior.

4) Conditioned reflexes help adapt to changing environmental conditions.

5) Unconditioned and conditioned reflexes help a person survive in this world.

2. Large molecules of proteins, fats and carbohydrates cannot pass through the walls of the digestive canal, so these substances are subjected to chemical treatment - digestion. Food is digested as it moves through the digestive organs.

Digestive glands:

1) three pairs of salivary glands:

In the oral cavity, in addition to the mechanical grinding of food, its chemical processing also begins. It is carried out by special enzymes that break down starch into glucose. People who smoke produce a lot of saliva, but the breakdown of starch is insufficient due to the action of substances contained in tobacco smoke.

2) liver:

The liver is the largest gland in our body. The liver produces bile, which travels through the cystic duct into the duodenum. The formation of bile in liver cells occurs continuously, but its release into the duodenum occurs only 5-10 minutes after eating and lasts 6-8 hours. In the absence of digestion, bile accumulates in the gallbladder. The daily amount of bile secreted by an adult is about 1 liter.

The production of bile in liver cells is only a small part of its overall role in the body. The liver is involved in the regulation of the metabolism of proteins, carbohydrates, vitamins, hormones and other biologically active substances, fats.

3) pancreas:

The pancreas consists of two types of cells. Some cells secrete digestive juice, others secrete hormones. Digestive juice enters the duodenum through two ducts.

The secretion of pancreatic juice begins a few minutes after eating and, depending on its composition, lasts 6-14 hours. A person secretes about 1.5-2.0 liters of pancreatic juice per day. Juice secretion is influenced by unconditioned reflex and conditioned reflex signals (the sight, smell of food, the sound of dishes, etc.). The center of the juice secretion reflex is located in the medulla oblongata.

4) many small glands in the stomach and intestines:

Intestinal juice is produced by glands in the mucous membrane of the small intestine. About 2 liters are released per day. The separation of juice does not occur continuously, but under the influence of irritants - dense parts of food, gastric juice, and protein breakdown products. Nervous and humoral mechanisms are involved in the regulation of the activity of the gastrointestinal glands. A large number of enzymes have been found in intestinal juice that act on all types of organic nutrients (proteins, fats, carbohydrates), on the products of their incomplete breakdown formed in the stomach, and ensure the completion of the digestion of nutrients.

Ticket No. 6

1. What is the structure and importance of the digestive system? §thirty

2. Name first aid techniques for various types of bleeding. Justify them. §23

Answers:

1. Expand the meaning of nutrition. Describe the structure and functions of the digestive system.

Products of plant and animal origin, complementing each other, provide the body's cells with all the necessary nutrients. Water, mineral salts and vitamins are absorbed in the form in which they are contained in food. Large molecules of proteins, fats and carbohydrates cannot pass through the walls of the digestive canal, so these substances are subjected to chemical treatment - digestion. Food is digested as it moves through the digestive organs. Nutrition is a necessary condition for normal growth, development and functioning of the body.

The meaning of nutrition is to provide the body with nutrients: proteins, fats, carbohydrates, mineral salts, water and vitamins, that is, to ensure the development and vital functions of the body.

2. Describe first aid measures for various types of bleeding.

Carrying out practical work on unconditioned reflexes:

Introduction (relevance)

The concept of reflex is very important in physiology. This concept explains the automated work of the body to quickly adapt to changes in the environment.

With the help of reflexes, the nervous system coordinates the activities of the body with signals coming from the surrounding external and internal environment.

Reflex (reflection) is the basic principle and way of working of the nervous system. A more general concept is reactivity . These concepts imply that the reason for the behavioral activity of the organism lies not in the psyche, but out of psyche , outside the nervous system, and is triggered by signals external to the psyche and the nervous system - stimuli. Also implied determinism , i.e. predetermination of behavior due to the cause-and-effect relationship between the stimulus and the body’s response to it.

The concepts of “reflex” and “reflex arc” relate to the field of physiology of the nervous system and they must be understood to the level of complete understanding and clarity in order to understand many other topics and sections of physiology.

Definition of the concept

A simple definition of the concept "reflex"

Reflex is responsiveness. You can give such a definition to a reflex, but after that it is necessary to name 6 important criteria (signs) of a reflex that characterize it. They are listed below in the full definition of the concept of reflex.

A reflex is a stereotypical automated adaptive responsiveness to a stimulus (irritant).

A reflex in a general broad sense is secondary a phenomenon caused by another phenomenon (primary), i.e. reflection, a consequence in relation to something original. In physiology, a reflex is responsiveness the body to an incoming signal, the source of which is outside the psyche, when the triggering signal (stimulus) is the primary phenomenon, and the reaction to it is secondary, reactive.

A complete definition of the concept "reflex"

Physiological definition of the concept "reflex arc"

Reflex arc - this is a schematic path of excitation movement from the receptor to the effector.

We can say that this is the path of nervous excitation from the place of its birth to the place of application, as well as the path from the information input to the information output from the body. This is what a reflex arc is from a physiological point of view.

Anatomical definition of the concept "reflex arc"

Reflex arc - this is a set of nervous structures involved in the implementation of a reflex act.

Both of these definitions of the reflex arc are correct, but for some reason the anatomical definition is more often used, although the concept of a reflex arc refers to physiology, not anatomy.

Remember that the diagram of any reflex arc must begin with irritant , although the stimulus itself is not part of the reflex arc. The reflex arc ends with the organ effector , which gives a response.

Stimulus - this is a physical factor that, when exposed to sensory receptors adequate for it, generates nervous excitement in them.

The stimulus triggers transduction in the receptors, as a result of which irritation is converted into excitation.

Electric current is a universal stimulus because it can generate excitation not only in sensory receptors, but also in neurons, nerve fibers, glands and muscles.

Variants of the result of the effect of an irritant on the body

1. Launching an unconditioned reflex.

2. Triggering a conditioned reflex.

3. Launch of the orientation reflex.

4. Launching the dominant.

5. Launch of a functional system.

6. Triggering emotions.

7. Launching the creation of a neural model (in particular, a sensory image), the learning/memorization process.

8. Trigger memories.

There are not many types of effectors.

Types of effectoro V:

1) striated muscles of the body (fast white and slow red),

2) smooth muscles of blood vessels and internal organs,

3) exocrine glands (for example, salivary glands),

4) endocrine glands (for example, adrenal glands).

Accordingly, responses will be the result of the activity of these effectors, i.e. contraction or relaxation of muscles, leading to movements of the body or internal organs and blood vessels, or secretion of secretions by glands.

Concept of temporary neural connection

“A temporary connection is a set of biochemical, neurophysiological and, possibly, ultrastructural changes in the brain that arise in the process of combining conditioned and unconditioned stimuli and form strictly defined relationships between structural formations that underlie various brain mechanisms. The memory mechanism records these relationships, ensuring their retention and reproduction." (Khananashvili M.M., 1972).

Meanwhile, the meaning of this tricky definition boils down to the following:

Temporary neural connection - this is the flexible part catch reflex arc, formed during the development of a conditioned reflex to connect two undoubtedly reflex arcs. It ensures the conduction of excitation between the nerve centers of two different unconditioned reflexes. Initially, one of these two unconditioned reflexes is triggered by a weak stimulus ("conditioned"), and the second by a strong one ("unconditioned" or "reinforcement"), but when a conditioned reflex has already been developed, the weak conditioned stimulus gets the opportunity to trigger an "alien" unconditioned reaction for due to the transition of excitation from its nerve center to the nerve center of a strong unconditioned stimulus.

Types of reflex arcs:

1. Elementary (simple) reflex arc of the unconditioned reflex. © 2015-2016 Sazonov V.F. © 2015-2016 kineziolog.bodhy.ru..

This reflex arc is the simplest, it contains only 5 elements. Although the figure shows more elements, from them we identify 5 main and necessary ones: receptor (2) - afferent ("carrying") neuron (4) - intercalary neuron (6) - efferent ("carrying out") neuron (7, 8 ) - effector (13).

It is important to understand the meaning of each element of the arc. Receptor : converts irritation into nervous excitement. Afferent neuron : delivers sensory stimulation to the central nervous system, to the interneuron. Interneuron : transforms the incoming excitement and directs it along the desired path. So, for example, an interneuron can receive sensory ("signal") excitation, and then transmit another excitation - motor ("control"). Efferent neuron : delivers control excitation to the effector organ. For example, motor excitation - on a muscle. Effector carries out a response.

The figure on the right shows a rudimentary reflex arc using the example of the knee reflex, which is so simple that it does not even have interneurons.

Please note that on the motor neuron that ends the reflex arc, many endings of neurons converge, located at different levels of the nervous system and seeking to control the activity of this motor neuron.

4. Double sided arc conditional reflex E.A. Asratyan. It shows that during the development of a conditioned reflex, opposing temporary connections are formed and both stimuli used are simultaneously both conditioned and unconditioned.

The figure on the right shows an animated diagram of a double conditioned reflex arc. It actually consists of two unconditioned reflex arcs: the left one is a blinking unconditioned reflex to irritation of the eye by an air flow (the effector is the contracting muscle of the eyelid), the right one is the salivary unconditioned reflex to irritation of the tongue with acid (the effector is the salivary gland that secretes saliva). Due to the formation of temporary conditioned reflex connections in the cerebral cortex, effectors begin to respond to stimuli that are normally inadequate for them: blinking in response to acid in the mouth and salivation in response to blowing air into the eye.

5. Reflex ring ON THE. Bernstein. This diagram shows how movement is reflexively adjusted depending on the achievement of the set goal.

6. Functional system to ensure appropriate behavior of P.K. Anokhina. This diagram shows the management of complex behavioral acts aimed at achieving a useful planned result. The main features of this model: action result acceptor and feedback between elements.

7. Double arc of the conditioned salivary reflex. This diagram shows that any conditioned reflex must consist of two reflex arcs formed by two different unconditioned reflexes, because Each stimulus (conditioned and unconditioned) generates its own unconditioned reflex.

An example of an experimental protocol for developing a conditioned pupillary reflex to sound in a laboratory lesson

(lat. reflexus - turned back, reflected) - the body’s response to certain influences carried out through the nervous system. There are R. unconditional (congenital) and conditional (acquired by the body during an individual life, having the property of disappearing and being restored). Fr. philosopher R. Descartes was the first to point out the reflex principle in brain activity. N.D. Naumov

Excellent definition

Incomplete definition ↓

REFLEX

from lat. reflexus – turning back; in a figurative meaning – reflection) – a general principle for regulating the behavior of living systems; engine (or secretory) act that has an adaptability. meaning determined by the influence of signals on receptors and mediated by nerve centers. The concept of R. was introduced by Descartes and served the task of deterministically explaining, within the framework of mechanism. pictures of the world, the behavior of organisms based on the general laws of physics. interaction of macrobodies. Descartes rejected the soul as he explains. motor principle activity of the animal and described this activity as the result of a strictly natural response of the “machine-body” to external influences. Based on the mechanistically understood principle of R., Descartes tried to explain certain mental. functions, in particular learning and emotions. All subsequent neuromuscular physiology was under the determining influence of the doctrine of R. Some followers of this doctrine (Dilli, Swammerdam) back in the 17th century. expressed a guess about the reflexive nature of all human behavior. This line was completed in the 18th century. La Mettrie. Ch. the enemy of deterministic view of R. came out with vitalism (Stahl and others), which argued that not a single organic. the function is not carried out automatically, but everything is directed and controlled by the sentient soul. In the 18th century Witt discovered that dep. a segment of the spinal cord is sufficient to carry out an involuntary muscle reaction, but he considered its determinant to be a special “sensitive principle”. The problem of the dependence of movement on sensation, used by Witt to prove the primacy of feeling in relation to the work of the muscle, materialistic. the interpretation was given by Hartley, who pointed out that sensation actually precedes movement, but it itself is caused by a change in the state of moving matter. Opening specific. signs of neuromuscular activity prompted naturalists to introduce the concept of “forces” inherent in the body and distinguishing it from other natural bodies (“muscular and nervous force” by Haller, “nervous force” by Unzer and Prohaska), and the interpretation of force was materialistic. Creatures Contribution to the further development of the doctrine of R. was made by Prohaska, who proposed biological. R.'s explanation as a purposeful act regulated by a sense of self-preservation, under the influence of which the body evaluates external stimuli. The development of the anatomy of the nervous system led to the discovery of the mechanism of the simplest reflex arc (Bell-Magendie law). A scheme for the localization of reflex pathways emerges, based on the cut in the 30s. 19th century the classic is maturing. doctrine about R. as the principle of operation of the spinal centers, in contrast to the higher parts of the brain. It was substantiated by Marshall Hall and I. Muller. This is purely physiological. the teaching exhaustively explained the definition. category of nervous acts by the influence of an external stimulus on a specific. anatomical structure. But the idea of ​​R. as mechanical. "blind" movement, predetermined anatomically. the structure of the organism and independent of what is happening in the external environment, forced us to resort to the idea of ​​a force that selects from a set of reflex arcs those needed in given circumstances and synthesizes them into a holistic act in accordance with the object or situation of action. This concept has been subjected to sharp experimental-theoretical research. criticism from materialistic positions by Pflueger (1853), who proved that lower vertebrates, lacking a brain, are not purely reflex automata, but vary their behavior with changing conditions, and that, along with the reflex function, there is a sensory function. The weak side of Pflueger’s position was the opposition of R. to the sensory function, the transformation of the latter into the finite will explain. concept. Sechenov brought the theory of R. to a new path. The former is purely morphological. He transformed R.’s scheme into a neurodynamic one, bringing the center connection to the foreground. processes in natural groups. The regulator of movement was recognized as feeling of varying degrees of organization and integration - from the simplest sensation to the dismembered sensory, and then the mind. an image that reproduces the objective characteristics of the environment. Accordingly, the afferent phase of the interaction of the organism with the environment was not thought of as mechanical. contact, but as the acquisition of information that determines the subsequent course of the process. The function of the centers was interpreted in a broad biological sense. adaptation. Engine activity acted as a factor that has a reverse influence on the construction of behavior - external and internal (feedback principle). Subsequently, a major contribution to the development of physiological. ideas about the mechanism of R. were introduced by Sherrington, who studied the integrative and adaptive originality of nervous acts. However, in the understanding of mental he adhered to dualistic functions of the brain. views. I.P. Pavlov, continuing the line of Sechenov, experimentally established the difference between unconditional and conditional R. and discovered the laws and mechanisms of reflex work of the brain, forming physiological. basis of mental activities. Subsequent study of complex adaptations. acts supplemented the general scheme of R. with a number of new ideas about the mechanism of self-regulation (N. A. Bernstein, P.K. Anokhin, etc.). Lit.: Sechenov I.M., Physiology of the nervous system, St. Petersburg, 1866; Immortal B.S., One Hundred Years of the Belle-Magendie Doctrine, in the book: Archives of Biol. Sciences, vol. 49, no. 1, ?., 1938; Conradi G.P., On the history of the development of the doctrine of R., ibid., vol. 59, no. 3, M., 1940; Anokhin P.K., From Descartes to Pavlov, M., 1945; Pavlov I. P., Izbr. works, M., 1951; Yaroshevsky M. G., History of Psychology, M., 1966; Gray Walter W., The Living Brain, trans. from English, M., 1966; Eckhard S., Geschichte der Entwicklung der Lehre von den Reflexerscheinungen, "Beitr?ge zur Anatomie und Physiologie", 1881, Bd 9; Fulton J. F., Muscular contraction and the reflex control of movement, L., 1926; Fearing F., Reflex action. A study in the history of physiological psychology, L., 1930; Bastholm E., The history of muscle physiology, Copenhagen, 1950. M. Yaroshevsky. Leningrad. The current state of the study of R. Advances in the physiology of the nervous system and the close contact of general neurophysiology and the physiology of higher nervous activity with biophysics and cybernetics have extremely expanded and deepened the understanding of R. at the physicochemical, neural, and system levels. Physico-chemical level. An electron microscope showed the subtle mechanism of the chemical. transferring excitation from neuron to neuron by emptying transmitter bubbles into the synaptic. cracks (E. de Robertis, 1959). At the same time, the nature of the excitation wave in the nerve is determined, as 100 years ago by L. Herman (1868), in the form of physical. action current, short-term electric impulse (B. Katz, 1961). But along with electrical ones, metabolic ones are taken into account. excitation components, e.g. "sodium pump" generating electricity. current (A. Hodgkin and A. Huxley, 1952). Neural level. Even Ch. Sherrington (1947) associated certain properties of simple spinal R., for example. reciprocity of excitation and inhibition, with a hypothetical neuron connection diagrams. I. S. Beritashvili (1956) based on cytoarchitectonic. data made a number of assumptions about various forms of organization of neurons in the cerebral cortex, in particular about the reproduction of images of the external world by the system of stellate cells of the eye. analyzer of lower animals. The general theory of the neural organization of reflex centers was proposed by W. McCulloch and V. Pite (1943), who used mathematical apparatus. logic for modeling the functions of neural circuits in a rigidly deterministic manner. networks of formal neurons. However, many The properties of higher nervous activity do not fit into the theory of fixed nerve networks. Based on the results of electrophysiological. and morphological studying the interconnection of neurons in the higher parts of the brain, a hypothesis of their probabilistic-statistical organization is developed. According to this hypothesis, the regularity of the reflex reaction is ensured not by the unambiguous path of signals along fixed interneuron connections, but by the probabilistic distribution of their flows across sets. ways and statistical way to achieve the final result. Randomness in the interaction of neurons was assumed by D. Hebb (1949), A. Fessar (1962) and other researchers, and W. Gray Walter (1962) showed statistical data. the nature of conditional R. Often neural networks with fixed connections are called deterministic, contrasting them with networks with random connections as indeterministic. However, stochasticity does not mean indeterminism, but, on the contrary, provides the highest, most flexible form of determinism, which apparently lies at the basis of the Holy Rule. plasticity R. System level. The system of even simple unconditional R., for example. pupillary, consists of a number of self-regulating subsystems with linear and nonlinear operators (M. Clynes, 1963). Assessing the correspondence of the current stimuli and the “nervous model of the stimulus” (E. N. Sokolov, 1959) turned out to be an important factor in the biologically expedient organization of R. Taking into account the mechanisms of self-regulation through feedback, the presence of which was written by Sechenov (1863), the structure of R. in modern cybernetic aspect began to be represented not as an open reflex arc, but as a closed reflex ring (N.A. Bernstein, 1963). Recently, discussions have arisen about the content of the concepts of signaling, reinforcement and temporary connections of conditional R. Thus, P.K. Anokhin (1963) considers signaling as a manifestation of the work of the mechanism for “predicting” events in the external world, and reinforcement as the formation of cyclical. structures for monitoring the results of action. E. A. Asratyan (1963) emphasizes qualities. differences between the connections of conditional R. and short-term ones. reactions such as trampling and dominance. Lit.: Beritashvili I. S., Morphological. and physiological foundations of temporary connections in the cerebral cortex, "Tr. Institute of Physiology named after I. S. Beritashvili", 1956, v. 10; McCulloch, W. S. and Pitts, W., Logic. calculus of ideas relating to nervous activity, [trans. from English], in the collection: Avtomaty, M., 1956; Sokolov E.N., Nervous model of stimulus, "Doc. APN RSFSR", 1959, No. 4; Katz B., The nature of the nerve impulse, in: Sovrem. problems of biophysics, vol. 2, M., 1961; Hartline X., Receptor mechanisms and integration of sensory information in the retina, ibid.; Walter G. W., Stat. approach to the theory of conditioned R., in the book: Electroencephalographic. study of higher nervous activity, M., 1962; Fessar?., Analysis of the closure of temporary connections at the neuronal level, ibid.; Smirnov G.D., Neurons and functional. organization of the nerve center, in: Gagra Conversations, vol. 4, Tb., 1963; Philosophy question Physiology of Higher Nervous Activity and Psychology, M., 1963 (see article by P.K. Anokhin, E.A. Asratyan and N.A. Bernstein); Kogan A. B., Probabilistic-statistical. the principle of neural organization of functional systems of the brain, "DAN USSR", 1964, v. 154, No. 5; Sherrington Ch. S., The integrative action of the nervous system, , 1947; Hodgkin A. L., Huxley A. F., A quantitative description of membrane current and its application to conduction and excitation in nerve, "J. physiol.", 1952, v. 117, No. 4; Hebb D. O., The organization of behavior, N. Y.–L., ; Robertis Ed. de, Submicroscopic morphology of the synapse, "Intern. Rev. Cytol.", 1959, v. 8, p. 61–96. A. Kogan. Rostov n/a.