Functions of reflexes. Types of reflexes and their features

24.11.202227.05.2017

The term “reflex” was introduced by the French scientist R. Descartes in the 17th century. But to explain mental activity it was used by the founder of Russian materialistic physiology I.M. Sechenov. Developing the teachings of I.M. Sechenov. I. P. Pavlov experimentally studied the peculiarities of the functioning of reflexes and used the conditioned reflex as a method for studying higher nervous activity.

He divided all reflexes into two groups:

unconditional;
conditional.

Unconditioned reflexes

Unconditioned reflexes- innate reactions of the body to vital stimuli (food, danger, etc.).

They do not require any conditions for their production (for example, the release of saliva at the sight of food). Unconditioned reflexes are a natural reserve of ready-made, stereotypical reactions of the body. They arose as a result of the long evolutionary development of this animal species. Unconditioned reflexes are the same in all individuals of the same species. They are carried out using the spinal and lower parts of the brain. Complex complexes of unconditioned reflexes manifest themselves in the form of instincts.

Rice. 1. The location of some functional zones in the human cerebral cortex: 1 - zone of speech production (Broca's center), 2 - area of the motor analyzer, 3 - area of analysis of oral verbal signals (Wernicke's center), 4 - area of the auditory analyzer, 5 - analysis of written verbal signals, 6 - visual analyzer area

Conditioned reflexes

But the behavior of higher animals is characterized not only by innate, i.e., unconditioned reactions, but also by such reactions that are acquired by a given organism in the process of individual life activity, i.e. conditioned reflexes. The biological meaning of the conditioned reflex is that numerous external stimuli that surround the animal in natural conditions and in themselves do not have vital significance, preceding in the animal’s experience food or danger, the satisfaction of other biological needs, begin to act as signals, by which the animal orients its behavior (Fig. 2).

So, mechanism of hereditary adaptation- an unconditioned reflex, and the mechanism of individual variable adaptation is a conditioned reflex, developed by combining vital phenomena with accompanying signals.

Rice. 2. Scheme of formation of a conditioned reflex

a - salivation is caused by an unconditioned stimulus - food;
b - excitation from a food stimulus is associated with a previous indifferent stimulus (light bulb);
c - the light of the light bulb became a signal of the possible appearance of food: a conditioned reflex was developed to it

A conditioned reflex is developed on the basis of any of the unconditioned reactions. Reflexes to unusual signals that do not occur in a natural environment are called artificial conditioned. In laboratory conditions, it is possible to develop many conditioned reflexes to any artificial stimulus.

I. P. Pavlov associated with the concept of a conditioned reflex principle of signaling of higher nervous activity, the principle of synthesis of external influences and internal states.

Pavlov's discovery of the basic mechanism of higher nervous activity - the conditioned reflex - became one of the revolutionary achievements of natural science, a historical turning point in the understanding of the connection between the physiological and the mental.

Understanding the dynamics of formation and changes in conditioned reflexes began the discovery of complex mechanisms of human brain activity and the identification of patterns of higher nervous activity.

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 the implementation of 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 due to the interaction of the processes of excitation and inhibition.

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 during 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 adaptation of the body 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.

reflexes) R. is the least complex motor reaction of C. n. With. to the sensory input signal, carried out with minimal delay. R.'s expression is an involuntary, stereotypical act, determined by the locus and nature of the stimulus that causes it. However, over many R. can be under conscious control. R. can be caused by stimulation of any sensory modality. There are a lot of R., and we will not give a complete list of them here. Instead, for several With specific examples we will illustrate those principles that apply to all R. The simplest reflex is the myotatic reflex, or muscle stretch reflex. This reflex can be induced in any skeletal muscle, although the most famous example is the knee reflex. Anat. The basis of the myotatic reflex is a monosynaptic (with one synapse) reflex arc. It includes a sensory end organ, a sensory nerve fiber with its cell body in the dorsal root ganglion, an α-motoneuron, on which the sensory axon forms a synapse, and an axon of this β-motoneuron returning to the muscle, from which the sensory fiber comes. The sensory end organ in the muscle stretch reflex is the muscle spindle. The muscle spindle has muscle endings called. intrafusal fibers, and a central, non-muscular region associated with the ending of the afferent nerve. Intrafusal fibers are innervated by α-motoneurons of the anterior roots of the spinal cord. Higher centers of the brain can influence the muscle stretch reflex by modulating the activity of α-motoneurons. This reflex is caused by stretching of the muscle, which leads to an increase in the length of the muscle spindle and, consequently, to an increase in the frequency of action potential generation in the sensory (afferent) nerve fiber. Increased activity in the afferent fiber increases the discharge of the target motor neuron, which causes contraction of the extrafusal fibers of the muscle, from which the afferent signal comes. When extrafusal fibers contract, the muscle shortens and activity in the afferent fibers decreases. There are also more complex reflex arcs, including one or several. intercalary neurons between the afferent and efferent parts of the reflex. An example of the simplest polysynaptic (with more than one synapse) reflex is the tendon reflex. The sensory end organ, the Golgi corpuscle, is located in the tendons. An increase in the load on the tendon, usually caused by contraction of the muscle attached to it, is an exciting stimulus, which leads to stretching of the Golgi bodies and the emergence of impulse activity in them, widespread. according to afferent fiber. The afferent coming from the tendon sensory end organ ends at an interneuron in the spinal cord. This interneuron has an inhibitory effect on the β-motoneuron, reducing activity in its efferent axon. As this axon returns to the muscle attached to the stretched tendon, the muscle relaxes and the stress on the tendon is reduced. The muscle stretch reflex and tendon reflex work in concert to provide the basic mechanism for quickly regulating the degree of muscle contraction. These R. are useful for quick adaptations to changes in the position of the leg when a person. you have to walk on uneven ground. Of course, other polysynaptic spinal R. also participate in locomotion. These R. include many more interneurons in the structure of the reflex arc. The neurological basis of these complex R. is formed by divergent (from one neuron to several) and convergent (from several neurons to one) connections of interneurons. An example of the action of these R. is given to us by a person stepping with his bare foot on a sharp object and reflexively withdrawing his wounded leg. The sensory input here is pain. Pain afferent fibers travel to the spinal cord and form synapses on interneurons. Some of these interneurons excite motor neurons, which cause the flexor muscles of the injured leg to contract, pulling the leg up, but other interneurons contribute to the inhibition of motor neurons serving the extensor muscles of the same leg. This allows the leg to rise quickly and smoothly. Dr. neurons receiving pain input send axons across the midline of the spinal cord, excite the extensor motor neurons of the opposite leg and inhibit the motor neurons innervating its flexors. This causes the uninjured leg to become rigid and provide support as the injured leg is pulled upward. On top of that, interneurons also relay information. into the upper and lower parts of the spinal cord, causing intersegmental R., which coordinate the contraction of the muscles of the trunk and upper extremities. Monosynaptic and polysynaptic spinal nerve fibers form the basic mechanism for maintaining and adapting posture. Motor systems of the brain influence spinal nerves through input circuits going to interneurons and β-motoneurons. Thus, changes in spinal R. may indicate pathology in the motor systems of the brain. An example of this is hyperreflexia associated with injury to the lateral spinal motor tract or damage to the motor areas of the frontal lobe. There are a number of visual R. As an example, we can name. pupillary reflex, manifested in the constriction of the pupil in response to the illumination of the eye with bright light. This reflex requires an intact retina, optic nerve, midbrain, and third pair of cranial nerves, but does not depend on the integrity of the nuclei of the lateral geniculate body or the visual cortex. R. tj can be caused by stimulation of sensory input from internal organs. The baroreceptor reflex is an example of such an autonomic reflex. Increased blood pressure stretches receptors in large vessels near the heart. This enhances the flow of afferent impulses to the nuclei of the solitary tract of the medulla oblongata. Neurons in the nuclei of the solitary tract switch impulses to the motor nuclei of the vagus nerve and transmit them to the spinal cord, causing a decrease in heart rate and blood pressure. It is very difficult to gain conscious control over this reflex, but it is possible to develop a conditioned reflex on its basis using the technique of classical conditioning. See also Acetylcholinesterase, Electrical stimulation of the nervous system, Endorphins/enkephalins, Neural network models, Neurotransmitters, Sensorimotor processes M. L. Woodruff

REFLEX

reaction to receptor stimulation is a natural response of the body to a stimulus mediated by the nervous system. It is caused by the influence of a certain external or internal environmental factor on the analyzer. Manifests itself in muscle contraction and secretion. The principle of reflex in the activity of the brain was formulated by the French philosopher R. Descartes, although the term itself entered science later.

The manifestation of reflexes is unclear in protozoa, maximal in intestinal cavities, average in worms and insects, and gradually disappears in animals of a higher degree of development, but even in humans it does not disappear completely.

There are differences between unconditioned and conditioned reflexes.

Reflex

In psychology, the term has several meanings, ranging from a technical definition (innate behavior exhibited without conscious effort and not changing depending on the situation) to non-specific (an act carried out under the influence of an “impulse”). In the theory of classical conditioning, it is defined as “an unlearned association between stimuli and corresponding responses.” Thus, salivation at the sight of food is an unconditioned reflex.

REFLEX

jerk) is the body's response to one or another influence, carried out through the nervous system. For example, the knee jerk reflex (see Patellar reflex) consists of a sharp “throwing” movement of the leg, resulting from contraction of the quadriceps femoris muscle in response to stretching when tapping its tendon. Determining this, as well as some other reflexes, such as the Achilles and ulnar extensor reflex, allows you to monitor the state of the spinal nerves that are involved in these reflexes.

REFLEX

reflex) - the body's response to certain influences carried out through the nervous system. Thus, a painful stimulus (for example, a pin prick) will lead to the emergence of a reflex of withdrawing the finger even before the brain sends a message about the need for the muscles to participate in this process. See Conditioned reflex, Patellar reflex. Plantar reflex.

Reflex

Word formation. Comes from Lat. reflexus - reflected.

Specificity. Manifests itself in muscle contraction, secretion, etc.

Conditioned reflexes,

Unconditioned reflexes.

REFLEX

1. In general - any relatively simple, “mechanical” reaction. Reflexes are usually viewed as species-specific, innate patterns of behavior that are largely beyond the control of will and choice and show little variability from individual to individual. This value is preferred in specialized literature. 2. Not acquired connection between the response and the stimulus. This meaning simply extends the first to include in the definition the presence of a stimulus that causes a reflex. 3. More metaphorical meaning - any unconscious, impulsive action. This value is significantly broader than the previous ones, although it is not generally recommended. Many authors use the terms reflex and reaction interchangeably, despite the fact that the term reaction does not carry any connotations of species-specific, innate qualities that the concept of reflex has (at least in its basic meaning). Consequently, many compound terms are used in the literature with either of these two general names; for example, the so-called startle response is often called the startle reflex. See reaction.

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 growth.
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 action of direct current (electrotone, cathodic depression, accommodation).
18.7 The ratio of the phases of the change in excitability during excitation with the phases of the action potential.
19.8 Structure and classification of synapses. The 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 the conduction of signals in excitatory and inhibitory synapses.
21Determination of mediators 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 magnitude. 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 due to 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 of postsynaptic, presynaptic and their mechanisms.
Question 33.5 Definition of coordination in the central nervous system. The main principles of the coordination activity of the central nervous system: reciprocity, a common "final" path, dominant, temporal connection, feedback.
Question 35.7 The medulla oblongata and the bridge, 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 the motor (alpha-rigidity) and vegetative 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, motivations, stress.
Question 42.14 The limbic system of the brain, its role in the formation of motivations, emotions, self-regulation of autonomic functions.
Question 43.15 Thalamus, functional characteristics and features of the nuclear groups of the thalamus.
44.16. The role of the basal nuclei in the formation of muscle tone and complex motor acts.
45.17 Structural and functional organization of the cerebral cortex, projection and associative zones. Plasticity of cortex functions.
46.18 Functional asymmetry of the cerebral 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 Departments of autonomic NS, relative physiological antagonism and biological synergism of their influences on the 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 value. 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
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

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) to some external stimulus.

By ordinary reflexes we mean a machine-like reaction, which, other things being equal, is characterized by stereotypical constancy and which, repeated each time with the same external stimulation, can change to one degree or another only quantitatively. The noticeable differences in the strength of the reflex reaction are partly due to the strength of external stimulation, and mainly to the phenomena of internal or external inhibition; Otherwise, these reactions develop with constant consistency every time a certain external influence is applied to a certain area of the body. (Bekhterev V.M. Objective psychology. p. 144).

The reflex is that in response to familiar circumstances the animal responds with a habitual, innate or acquired response.

This can be either one or another single stimulus, or a combination of various stimuli. A child's cry is a single stimulus. A child who runs to his mother, cries and stretches his arms towards her - a combination of irritants...

In more detail, a reflex is the body’s response to irritation, carried out through excitation of the central nervous system and having adaptive significance. This definition contains 5 signs of a reflex: 1) it is a response and not spontaneous, 2) irritation is necessary, without which the reflex does not occur, 3) the reflex is based on nervous excitation, 4) the participation of the central nervous system is necessary to transform sensory excitation in the effector, 5) the reflex is needed to adapt (adapt) to changing environmental conditions.

The circumstance that triggers the reflex can be either one or another single stimulus, or a combination of various stimuli. The cry of a child is a single irritant for a mother. A child who runs to his mother, cries and stretches his arms towards her - a combination of irritants... But what will be the reaction of the mother, “What are you yelling at?” or “Come here, honey, your mother will feel sorry for you!”, depends on how the mother was raised, on her already learned reflexes.

In everyday life, instead of the word “reflexes”, people outside science more often use the words “habit”, “impulse”, “movement of the soul”...

As we have already said, reflexes are divided into congenital and acquired. We are all born with one or another innate reflex, from the knee and breathing reflex to the defensive reflex, fear reflex or goal reflex.

The theory of reflexes was developed by I.P. Pavlov and V.M. Bekhterev, the contribution of both was enormous. However, after the death of V.M. Bekhterev's legacy was practically forgotten, only I.P. remained in the spotlight. Pavlov and the research of his school, primarily the concept of the “conditioned reflex”. Conditioned reflex according to I.P. Pavlov, this is the triggering of an unconditioned reflex to a conditioned stimulus (signal) as a result of multiple coincidence (combination) of the signal and the unconditioned reflex, and the conditioned stimulus must act first, performing the function of a signal about what will follow it.

Most of his research I.P. Pavlov conducted on dogs; his most famous experiments were the study of salivation in response to a light bulb or the sound of a bell. When a dog sees food, its salivary glands begin to secrete saliva. This always happens in any dog, it is an unconditioned reflex. If a dog hears a bell, at first it has an indicative reaction (the dog tenses and turns its head), but over time this reaction disappears, and the dog no longer reacts to the bell. However, if the bell regularly rang at the time of feeding, or rather right before it, then after a while the dog developed a conditioned reflex: the bell itself began to cause it to salivate.

The difference in terminology is interesting: if the acquired reflexes of I.P. Pavlov called “conditioned reflexes”, then V.M. Bekhterev - “combining” or “combining-motor reflexes”. In addition to the difference in terminology, there is some difference in the content of the concepts. In the Pavlovian conditioned reflex, the conditioned stimulus must act first, performing the function of a signal that it will follow, while associative reflexes, according to Bekhterev, can arise both in the case of a slight advance of the neutral stimulus and in the case of its slight delay. Thus, “combinative” reflexes according to Bekhterev include both “conditioned reflexes” according to Pavlov and “operational behavior” according to B. Skinner.

Indeed, it turned out that in contrast to the conditioned reflex, in which the appearance of a reaction to a conditioned signal is always preceded by its reinforcement, an animal can form a reaction that in the past was reinforced by its manifestation: not as a signal of what will happen, but as reinforcement of what will happen. what the animal has already done.

This mechanism is called operant conditioning. Operant conditioning can be considered as a type of combinational reflexes, where a stable connection arises between a certain type of behavior and its consequences, namely its positive or negative reinforcement. In operant conditioning, it is not the dog's salivation that is studied, but its behavior: for example, under what conditions will the dog run to the door and, for example, bark three times at the door.

However, calling operant behavior a reflex is inaccurate. B. Skinner wrote about the difference between reflexes and operant behavior: “Reflexes, both conditioned and all other, are mainly associated with internal physiological processes in the body. However, most often we are interested in behavior that has a certain impact on the world around us. arises as a result of a person’s collision with the need to solve the problems put forward by life.” When reacting (when performing a conditioned reflex), the animal plays a passive role: the owner gave a command - the dog did it. The active beginning of behavior is in humans. In operant behavior, on the contrary, the source of activity is the animal: the dog performs an action in order to be rewarded.

It is quite important to distinguish between reflex and instinct. A reflex, unlike an instinct, is triggered by a simple stimulus (a certain sound, impact, flash of light, and so on). It occurs at the moment when the body is affected by a stimulus of such force that it is sufficient to trigger the reflex (i.e. threshold force), and is triggered regardless of the presence or absence. Instinct, unlike a reflex, is triggered by complex stimuli and is triggered only in the presence of a motivational state:

For example, for a dog to begin defending territory, it must see an approaching enemy - see, hear, feel - a whole set of stimuli.

The same dog, finding itself in a new territory, will not defend it, but will explore it - and even if at that moment the same “enemy” passes nearby, the instinct to protect the territory will not work - there is no motivation.

Unconditioned reflexes

Conditioned reflexes

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