Methods for studying the central nervous system

The most widely used methods for recording the bioelectrical activity of individual neurons, the total activity of the neuronal pool or the brain as a whole (electroencephalography), computed tomography (positron emission tomography, magnetic resonance imaging), etc.

Electroencephalography - this is registration from the surface of the skin head or from the surface of the cortex (the latter in the experiment) the total electric field of brain neurons when they are excited(Fig. 82).

Rice. 82. Electroencephalogram rhythms: A – basic rhythms: 1 – α-rhythm, 2 – β-rhythm, 3 – θ-rhythm, 4 – σ-rhythm; B – reaction of EEG desynchronization of the occipital region of the cerebral cortex when opening the eyes () and restoration of the α rhythm when closing the eyes (↓)

The origin of EEG waves is not well understood. It is believed that the EEG reflects the LP of many neurons - EPSP, IPSP, trace - hyperpolarization and depolarization, capable of algebraic, spatial and temporal summation.

This point of view is generally accepted, while the participation of PD in the formation of the EEG is denied. For example, W. Willes (2004) writes: “As for action potentials, the resulting ionic currents are too weak, fast and unsynchronized to be recorded in the form of EEG.” However, this statement is not supported by experimental facts. To prove it, it is necessary to prevent the occurrence of APs of all neurons of the central nervous system and record the EEG under conditions of the occurrence of only EPSPs and IPSPs. But this is impossible. In addition, under natural conditions, EPSPs are usually the initial part of APs, so there is no reason to assert that APs do not participate in the formation of the EEG.

Thus, EEG is the registration of the total electric field of PD, EPSP, IPSP, trace hyperpolarization and depolarization of neurons.

The EEG records four main physiological rhythms: α-, β-, θ- and δ-rhythms, the frequency and amplitude of which reflect the degree of central nervous system activity.

When studying EEG, the frequency and amplitude of the rhythm are described (Fig. 83).

Rice. 83. Frequency and amplitude of the electroencephalogram rhythm. T 1, T 2, T 3 – period (time) of oscillation; number of oscillations in 1 second – rhythm frequency; A 1, A 2 – vibration amplitude (Kiroy, 2003).

Evoked potential method(EP) consists of recording changes in the electrical activity of the brain (electric field) (Fig. 84) that occur in response to irritation of sensory receptors (usual option).

Rice. 84. Evoked potentials in a person to a flash of light: P – positive, N – negative components of VP; digital indices indicate the order of positive and negative components in the composition of the VP. The start of recording coincides with the moment the light flashes (arrow)

Positron emission tomography- a method of functional isotope mapping of the brain, based on the introduction of isotopes (13 M, 18 P, 15 O) into the bloodstream in combination with deoxyglucose. The more active an area of ​​the brain, the more it absorbs labeled glucose. The radioactive radiation of the latter is recorded by special detectors. Information from the detectors is sent to a computer, which creates “slices” of the brain at a recorded level, reflecting the uneven distribution of the isotope due to the metabolic activity of brain structures, which makes it possible to judge possible damage to the central nervous system.

Magnetic resonance imaging allows you to identify actively working areas of the brain. The technique is based on the fact that after the dissociation of oxyhemoglobin, hemoglobin acquires paramagnetic properties. The higher the metabolic activity of the brain, the greater the volumetric and linear blood flow in a given region of the brain and the lower the ratio of paramagnetic deoxyhemoglobin to oxyhemoglobin. There are many foci of activation in the brain, which is reflected in the heterogeneity of the magnetic field.

Stereotactic method. The method allows the introduction of macro- and microelectrodes and a thermocouple into various structures of the brain. The coordinates of brain structures are given in stereotaxic atlases. By means of the introduced electrodes, it is possible to record the bioelectrical activity of a given structure, irritate or destroy it; through microcannulas, chemicals can be injected into the nerve centers or ventricles of the brain; Using microelectrodes (their diameter is less than 1 μm) placed close to the cell, it is possible to record the impulse activity of individual neurons and judge the participation of the latter in reflex, regulatory and behavioral reactions, as well as possible pathological processes and the use of appropriate therapeutic effects with pharmacological drugs.

Data about brain function can be obtained through brain surgery. In particular, with electrical stimulation of the cortex during neurosurgical operations.

Questions for self-control

1. What are the three sections of the cerebellum and their constituent elements in structural and functional terms? What receptors send impulses to the cerebellum?

2. What parts of the central nervous system is the cerebellum connected to through the inferior, middle and superior peduncles?

3. With the help of what nuclei and structures of the brain stem does the cerebellum realize its regulatory influence on the tone of skeletal muscles and motor activity of the body? Is it exciting or inhibitory?

4. What cerebellar structures are involved in the regulation of muscle tone, posture and balance?

5. What structure of the cerebellum is involved in programming goal-directed movements?

6. What effect does the cerebellum have on homeostasis, how does homeostasis change when the cerebellum is damaged?

7. List the parts of the central nervous system and structural elements that make up the forebrain.

8. Name the formations of the diencephalon. What skeletal muscle tone is observed in a diencephalic animal (the cerebral hemispheres have been removed), how is it expressed?

9. What groups and subgroups are the thalamic nuclei divided into and how are they connected to the cerebral cortex?

10. What are the names of neurons that send information to specific (projection) nuclei of the thalamus? What are the names of the paths that their axons form?

11. What is the role of the thalamus?

12. What functions do the nonspecific nuclei of the thalamus perform?

13. Name the functional significance of the association zones of the thalamus.

14. Which nuclei of the midbrain and diencephalon form the subcortical visual and auditory centers?

15. In what reactions, besides regulating the functions of internal organs, does the hypothalamus take part?

16. Which part of the brain is called the higher autonomic center? What is Claude Bernard's heat shot called?

17. What groups of chemical substances (neurosecrets) come from the hypothalamus to the anterior lobe of the pituitary gland and what is their significance? What hormones are released into the posterior lobe of the pituitary gland?

18. What receptors that perceive deviations from the norm in the parameters of the internal environment of the body are found in the hypothalamus?

19. Centers for regulating what biological needs are found in the hypothalamus

20. What brain structures make up the striopallidal system? What reactions occur in response to stimulation of its structures?

21. List the main functions in which the striatum plays an important role.

22. What is the functional relationship between the striatum and the globus pallidus? What movement disorders occur when the striatum is damaged?

23. What movement disorders occur when the globus pallidus is damaged?

24. Name the structural formations that make up the limbic system.

25. What is characteristic of the spread of excitation between the individual nuclei of the limbic system, as well as between the limbic system and the reticular formation? How is this ensured?

26. From what receptors and parts of the central nervous system do afferent impulses come to various formations of the limbic system, where does the limbic system send impulses?

27. What influences does the limbic system have on the cardiovascular, respiratory and digestive systems? Through what structures are these influences carried out?

28. Does the hippocampus play an important role in short-term or long-term memory processes? What experimental fact indicates this?

29. Provide experimental evidence demonstrating the important role of the limbic system in the species-specific behavior of an animal and its emotional reactions.

30. List the main functions of the limbic system.

31. Functions of the Peipets circle and the circle through the amygdala.

32. Cerebral cortex: ancient, old and new cortex. Localization and functions.

33. Gray and white matter of the CPB. Functions?

34.List the layers of the neocortex and their functions.

35. Fields Brodmann.

36. Columnar organization of the KBP in Mountcastle.

37. Functional division of the cortex: primary, secondary and tertiary zones.

38.Sensory, motor and associative zones of the KBP.

39. What does the projection of general sensitivity in the cortex mean (Sensitive homunculus according to Penfield). Where in the cortex are these projections located?

40.What does the projection of the motor system in the cortex mean (Motor homunculus according to Penfield). Where in the cortex are these projections located?

50. Name the somatosensory zones of the cerebral cortex, indicate their location and purpose.

51. Name the main motor areas of the cerebral cortex and their locations.

52.What are Wernicke's and Broca's areas? Where are they located? What consequences are observed when they are violated?

53. What is meant by a pyramid system? What is its function?

54. What is meant by the extrapyramidal system?

55. What are the functions of the extrapyramidal system?

56. What is the sequence of interaction between the sensory, motor and associative zones of the cortex when solving problems of recognizing an object and pronouncing its name?

57.What is interhemispheric asymmetry?

58.What functions does the corpus callosum perform and why is it cut in case of epilepsy?

59. Give examples of violations of interhemispheric asymmetry?

60.Compare the functions of the left and right hemispheres.

61.List the functions of the various lobes of the cortex.

62.Where in the cortex are praxis and gnosis carried out?

63.Neurons of which modality are located in the primary, secondary and associative zones of the cortex?

64.Which zones occupy the largest area in the cortex? Why?

66. In what areas of the cortex are visual sensations formed?

67. In what areas of the cortex are auditory sensations formed?

68. In what areas of the cortex are tactile and pain sensations formed?

69.What functions will a person lose if the frontal lobes are damaged?

70.What functions will a person lose if the occipital lobes are damaged?

71.What functions will a person lose if the temporal lobes are damaged?

72.What functions will a person lose if the parietal lobes are damaged?

73. Functions of associative areas of the KBP.

74.Methods for studying the functioning of the brain: EEG, MRI, PET, evoked potential method, stereotactic and others.

75.List the main functions of the PCU.

76. What is meant by plasticity of the nervous system? Explain using the example of the brain.

77. What functions of the brain will be lost if the cerebral cortex is removed in different animals?

2.3.15 . General characteristics of the autonomic nervous system

Autonomic nervous system- this is part of the nervous system that regulates the functioning of internal organs, the lumen of blood vessels, metabolism and energy, and homeostasis.

Departments of the VNS. Currently, two divisions of the ANS are generally recognized: sympathetic and parasympathetic. In Fig. 85 presents the sections of the ANS and the innervation of its sections (sympathetic and parasympathetic) of various organs.

Rice. 85. Anatomy of the autonomic nervous system. The organs and their sympathetic and parasympathetic innervation are shown. T 1 -L 2 – nerve centers of the sympathetic division of the ANS; S 2 -S 4 - nerve centers of the parasympathetic division of the ANS in the sacral part of the spinal cord, III-oculomotor nerve, VII-facial nerve, IX-glossopharyngeal nerve, X-vagus nerve - nerve centers of the parasympathetic division of the ANS in the brain stem

Table 10 shows the effects of the sympathetic and parasympathetic divisions of the ANS on effector organs, indicating the type of receptor on the cells of the effector organs (Chesnokova, 2007) (Table 10).

Table 10. The influence of the sympathetic and parasympathetic divisions of the autonomic nervous system on some effector organs

Organ	Sympathetic division of the ANS	Receptor	Parasympathetic division of the ANS	Receptor
Eye (iris)
Radial muscle	Reduction	α 1
Sphincter			Reduction	-
Heart
Sinus node	Increased frequency	β 1	Slowdown	M 2
Myocardium	Promotion	β 1	Demotion	M 2
Vessels (smooth muscle)
In the skin, in the internal organs	Reduction	α 1
In skeletal muscles	Relaxation	β 2		M 2
Bronchial muscles (respiration)	Relaxation	β 2	Reduction	M 3
Digestive tract
Smooth muscle	Relaxation	β 2	Reduction	M 2
Sphincters	Reduction	α 1	Relaxation	M 3
Secretion	Decline	α 1	Promotion	M 3
Leather
Hair muscles	Reduction	α 1		M 2
Sweat glands	Increased secretion			M 2

In recent years, convincing facts have been obtained proving the presence of serotonergic nerve fibers that run as part of the sympathetic trunks and enhance contractions of the smooth muscles of the gastrointestinal tract.

Autonomic reflex arc has the same links as the arc of the somatic reflex (Fig. 83).

Rice. 83. Reflex arc of the autonomic reflex: 1 – receptor; 2 – afferent link; 3 – central link; 4 – efferent link; 5 - effector

But there are features of its organization:

1. The main difference is that the ANS reflex arc may close outside the central nervous system- intra- or extraorgan.

2. Afferent link of the autonomic reflex arc can be formed by both its own - vegetative and somatic afferent fibers.

3. Segmentation is less pronounced in the arc of the autonomic reflex, which increases the reliability of autonomic innervation.

Classification of autonomic reflexes(by structural and functional organization):

1. Highlight central (various levels) And peripheral reflexes, which are divided into intra- and extraorgan.

2. Viscero-visceral reflexes- changes in the activity of the stomach when the small intestine is filled, inhibition of the activity of the heart when the P-receptors of the stomach are irritated (Goltz reflex), etc. The receptive fields of these reflexes are localized in different organs.

3. Viscerosomatic reflexes- change in somatic activity when the sensory receptors of the ANS are excited, for example, muscle contraction, movement of the limbs with strong irritation of the gastrointestinal tract receptors.

4. Somatovisceral reflexes. An example is the Danini-Aschner reflex - a decrease in heart rate when pressing on the eyeballs, a decrease in urine formation when the skin is painfully irritated.

5. Interoceptive, proprioceptive and exteroceptive reflexes - according to the receptors of reflexogenic zones.

Functional differences between the ANS and the somatic nervous system. They are associated with the structural features of the ANS and the severity of the influence of the cerebral cortex on it. Regulation of the functions of internal organs using the VNS can be carried out with a complete disruption of its connection with the central nervous system, but less completely. The effector neuron of the ANS is located outside the CNS: either in extra- or intraorgan autonomic ganglia, forming peripheral extra- and intraorgan reflex arcs. If the connection between muscles and the central nervous system is disrupted, somatic reflexes are eliminated, since all motor neurons are located in the central nervous system.

Influence of the VNS on organs and tissues of the body not controlled directly consciousness(a person cannot voluntarily control the frequency and strength of heart contractions, stomach contractions, etc.).

Generalized (diffuse) nature of the influence in the sympathetic division of the ANS is explained by two main factors.

Firstly, most adrenergic neurons have long postganglionic thin axons that branch repeatedly in organs and form the so-called adrenergic plexuses. The total length of the terminal branches of the adrenergic neuron can reach 10-30 cm. On these branches along their course there are numerous (250-300 per 1 mm) extensions in which norepinephrine is synthesized, stored and recaptured. When an adrenergic neuron is excited, norepinephrine is released from a large number of these extensions into the extracellular space, and it acts not on individual cells, but on many cells (for example, smooth muscle), since the distance to postsynaptic receptors reaches 1-2 thousand nm. One nerve fiber can innervate up to 10 thousand cells of the working organ. In the somatic nervous system, the segmental nature of innervation ensures more accurate sending of impulses to a specific muscle, to a group of muscle fibers. One motor neuron can innervate only a few muscle fibers (for example, in the muscles of the eye - 3-6, in the muscles of the fingers - 10-25).

Secondly, there are 50-100 times more postganglionic fibers than preganglionic fibers (there are more neurons in the ganglia than preganglionic fibers). In the parasympathetic ganglia, each preganglionic fiber contacts only 1-2 ganglion cells. Slight lability of neurons of the autonomic ganglia (10-15 impulses/s) and the speed of excitation in the autonomic nerves: 3-14 m/s in preganglionic fibers and 0.5-3 m/s in postganglionic fibers; in somatic nerve fibers - up to 120 m/s.

In organs with double innervation effector cells receive sympathetic and parasympathetic innervation(Fig. 81).

Each muscle cell of the gastrointestinal tract apparently has a triple extraorgan innervation - sympathetic (adrenergic), parasympathetic (cholinergic) and serotonergic, as well as innervation from neurons of the intraorgan nervous system. However, some of them, for example the bladder, receive mainly parasympathetic innervation, and a number of organs (sweat glands, muscles that lift the hair, spleen, adrenal glands) receive only sympathetic innervation.

Preganglionic fibers of the sympathetic and parasympathetic nervous systems are cholinergic(Fig. 86) and form synapses with ganglion neurons using ionotropic N-cholinergic receptors (mediator - acetylcholine).

Rice. 86. Neurons and receptors of the sympathetic and parasympathetic nervous system: A – adrenergic neurons, X – cholinergic neurons; solid line - preganglionic fibers; dotted line - postganglionic

The receptors got their name (D. Langley) because of their sensitivity to nicotine: small doses excite ganglion neurons, large doses block them. Sympathetic ganglia located extraorganically, Parasympathetic- usually, intraorganically. In the autonomic ganglia, in addition to acetylcholine, there are neuropeptides: metenkephalin, neurotensin, CCK, substance P. They perform modeling role. N-cholinergic receptors are also localized on the cells of skeletal muscles, carotid glomeruli and the adrenal medulla. N-cholinergic receptors of the neuromuscular junction and autonomic ganglia are blocked by various pharmacological drugs. Ganglia contain intercalary adrenergic cells that regulate the excitability of ganglion cells.

Mediators of postganglionic fibers of the sympathetic and parasympathetic nervous systems are different.

The study of the central nervous system includes a group of experimental and clinical methods. Experimental methods include cutting, extirpation, destruction of brain structures, as well as electrical stimulation and electrical coagulation. Clinical methods include electroencephalography, evoked potentials, tomography, etc.

Experimental methods

1. Cut and cut method. The method of cutting and switching off various parts of the central nervous system is done in various ways. Using this method, you can observe changes in conditioned reflex behavior.

2. Methods of cold switching off brain structures make it possible to visualize the spatio-temporal mosaic of electrical processes in the brain during the formation of a conditioned reflex in different functional states.

3. Methods of molecular biology are aimed at studying the role of DNA, RNA molecules and other biologically active substances in the formation of a conditioned reflex.

4. The stereotactic method consists in introducing an electrode into the animal’s subcortical structures, with which one can irritate, destroy, or inject chemicals. Thus, the animal is prepared for a chronic experiment. After the animal recovers, the conditioned reflex method is used.

Clinical methods

Clinical methods make it possible to objectively assess the sensory functions of the brain, the state of the pathways, the brain’s ability to perceive and analyze stimuli, as well as identify pathological signs of disruption of the higher functions of the cerebral cortex.

Electroencephalography

Electroencephalography is one of the most common electrophysiological methods for studying the central nervous system. Its essence lies in recording rhythmic changes in the potentials of certain areas of the cerebral cortex between two active electrodes (bipolar method) or an active electrode in a certain zone of the cortex and a passive electrode superimposed on an area remote from the brain.

Electroencephalogram is a recording curve of the total potential of the constantly changing bioelectrical activity of a significant group of nerve cells. This amount includes synaptic potentials and partly action potentials of neurons and nerve fibers. Total bioelectrical activity is recorded in the range from 1 to 50 Hz from electrodes located on the scalp. The same activity from the electrodes, but on the surface of the cerebral cortex is called electrocorticogram. When analyzing EEG, the frequency, amplitude, shape of individual waves and the repeatability of certain groups of waves are taken into account.

Amplitude measured as the distance from the baseline to the peak of the wave. In practice, due to the difficulty of determining the baseline, peak-to-peak amplitude measurements are used.

Under frequency refers to the number of complete cycles completed by a wave in 1 second. This indicator is measured in hertz. The reciprocal of the frequency is called period waves. The EEG records 4 main physiological rhythms: ά -, β -, θ -. and δ – rhythms.

α – rhythm has a frequency of 8-12 Hz, amplitude from 50 to 70 μV. It predominates in 85-95% of healthy people over nine years of age (except for those born blind) in a state of quiet wakefulness with eyes closed and is observed mainly in the occipital and parietal regions. If it dominates, then the EEG is considered as synchronized.

Synchronization reaction called an increase in amplitude and a decrease in frequency of the EEG. The EEG synchronization mechanism is associated with the activity of the output nuclei of the thalamus. A variant of the ά-rhythm are “sleep spindles” lasting 2-8 seconds, which are observed when falling asleep and represent regular alternations of increasing and decreasing amplitude of waves in the frequencies of the ά-rhythm. Rhythms of the same frequency are:

μ – rhythm, recorded in the Rolandic sulcus, having an arched or comb-shaped waveform with a frequency of 7-11 Hz and an amplitude of less than 50 μV;

κ - rhythm, noted when applying electrodes in the temporal lead, having a frequency of 8-12 Hz and an amplitude of about 45 μV.

β - rhythm has a frequency from 14 to 30 Hz and a low amplitude - from 25 to 30 μV. It replaces the ά rhythm during sensory stimulation and emotional arousal. The β rhythm is most pronounced in the precentral and frontal areas and reflects a high level of functional activity of the brain. The change from ά - rhythm (slow activity) to β - rhythm (fast low-amplitude activity) is called desynchronization EEG is explained by the activating influence on the cerebral cortex of the reticular formation of the brainstem and the limbic system.

θ – rhythm has a frequency from 3.5 to 7.5 Hz, amplitude from 5 to 200 μV. In a waking person, the θ rhythm is usually recorded in the anterior regions of the brain during prolonged emotional stress and is almost always recorded during the development of the phases of slow-wave sleep. It is clearly registered in children who are in a state of displeasure. The origin of the θ rhythm is associated with the activity of the bridge synchronizing system.

δ – rhythm has a frequency of 0.5-3.5 Hz, amplitude from 20 to 300 μV. Occasionally recorded in all areas of the brain. The appearance of this rhythm in a awake person indicates a decrease in the functional activity of the brain. Stably fixed during deep slow-wave sleep. The origin of the δ - EEG rhythm is associated with the activity of the bulbar synchronizing system.

γ – waves have a frequency of more than 30 Hz and an amplitude of about 2 μV. Localized in the precentral, frontal, temporal, parietal areas of the brain. When visually analyzing the EEG, two indicators are usually determined: the duration of the ά-rhythm and the blockade of the ά-rhythm, which is recorded when a particular stimulus is presented to the subject.

In addition, the EEG has special waves that differ from the background ones. These include: K-complex, λ - waves, μ - rhythm, spike, sharp wave.

K - complex- This is a combination of a slow wave with a sharp wave, followed by waves with a frequency of about 14 Hz. The K-complex occurs during sleep or spontaneously in a waking person. The maximum amplitude is observed in the vertex and usually does not exceed 200 μV.

Λ – waves- monophasic positive sharp waves arising in the occipital area associated with eye movements. Their amplitude is less than 50 μV, frequency is 12-14 Hz.

M – rhythm– a group of arc-shaped and comb-shaped waves with a frequency of 7-11 Hz and an amplitude of less than 50 μV. They are registered in the central areas of the cortex (Roland's sulcus) and are blocked by tactile stimulation or motor activity.

Spike– a wave clearly different from background activity, with a pronounced peak lasting from 20 to 70 ms. Its primary component is usually negative. Spike-slow wave is a sequence of superficially negative slow waves with a frequency of 2.5-3.5 Hz, each of which is associated with a spike.

sharp wave– a wave that differs from background activity with an emphasized peak lasting 70-200 ms.

At the slightest attraction of attention to a stimulus, desynchronization of the EEG develops, that is, a reaction of ά-rhythm blockade develops. A well-defined ά-rhythm is an indicator of the body’s rest. A stronger activation reaction is expressed not only in the blockade of the ά - rhythm, but also in the strengthening of high-frequency components of the EEG: β - and γ - activity. A decrease in the level of functional state is expressed in a decrease in the proportion of high-frequency components and an increase in the amplitude of slower rhythms - θ- and δ-oscillations.

Method for recording impulse activity of nerve cells

The impulse activity of individual neurons or a group of neurons can be assessed only in animals and, in some cases, in humans during brain surgery. To record neural impulse activity of the human brain, microelectrodes with tip diameters of 0.5-10 microns are used. They can be made of stainless steel, tungsten, platinum-iridium alloys or gold. The electrodes are inserted into the brain using special micromanipulators, which allow the electrode to be precisely positioned to the desired location. The electrical activity of an individual neuron has a certain rhythm, which naturally changes under different functional states. The electrical activity of a group of neurons has a complex structure and on a neurogram looks like the total activity of many neurons, excited at different times, differing in amplitude, frequency and phase. The received data is processed automatically using special programs.

Evoked potential method

The specific activity associated with a stimulus is called an evoked potential. In humans, this is the registration of fluctuations in electrical activity that appear on the EEG with a single stimulation of peripheral receptors (visual, auditory, tactile). In animals, afferent pathways and switching centers of afferent impulses are also irritated. Their amplitude is usually small, therefore, to effectively isolate evoked potentials, the technique of computer summation and averaging of EEG sections that was recorded during repeated presentation of the stimulus is used. The evoked potential consists of a sequence of negative and positive deviations from the baseline and lasts about 300 ms after the end of the stimulus. The amplitude and latency period of the evoked potential are determined. Some of the components of the evoked potential, which reflect the entry of afferent excitations into the cortex through specific nuclei of the thalamus, and have a short latent period, are called primary response. They are registered in the cortical projection zones of certain peripheral receptor zones. Later components that enter the cortex through the reticular formation of the brainstem, nonspecific nuclei of the thalamus and limbic system and have a longer latent period are called secondary responses. Secondary responses, unlike primary ones, are recorded not only in the primary projection zones, but also in other areas of the brain, connected by horizontal and vertical nerve pathways. The same evoked potential can be caused by many psychological processes, and the same mental processes can be associated with different evoked potentials.

Tomographic methods

Tomography– is based on obtaining images of brain slices using special techniques. The idea of ​​this method was proposed by J. Rawdon in 1927, who showed that the structure of an object can be reconstructed from the totality of its projections, and the object itself can be described by many of its projections.

CT scan is a modern method that allows you to visualize the structural features of the human brain using a computer and an X-ray machine. In a CT scan, a thin beam of X-rays is passed through the brain, the source of which rotates around the head in a given plane; The radiation passing through the skull is measured by a scintillation counter. In this way, X-ray images of each part of the brain are obtained from different points. Then, using a computer program, these data are used to calculate the radiation density of the tissue at each point of the plane under study. The result is a high-contrast image of a brain slice in a given plane. Positron emission tomography– a method that allows you to assess metabolic activity in different parts of the brain. The test subject ingests a radioactive compound, which makes it possible to trace changes in blood flow in a particular part of the brain, which indirectly indicates the level of metabolic activity in it. The essence of the method is that each positron emitted by a radioactive compound collides with an electron; in this case, both particles mutually annihilate with the emission of two γ-rays at an angle of 180°. These are detected by photodetectors located around the head, and their registration occurs only when two detectors located opposite each other are excited simultaneously. Based on the data obtained, an image is constructed in the appropriate plane, which reflects the radioactivity of different parts of the studied volume of brain tissue.

Nuclear magnetic resonance method(NMR imaging) allows you to visualize the structure of the brain without the use of X-rays and radioactive compounds. A very strong magnetic field is created around the subject's head, which affects the nuclei of hydrogen atoms, which have internal rotation. Under normal conditions, the rotation axes of each core have a random direction. In a magnetic field, they change orientation in accordance with the lines of force of this field. Turning off the field leads to the fact that the atoms lose the uniform direction of the axes of rotation and, as a result, emit energy. This energy is recorded by a sensor, and the information is transmitted to a computer. The cycle of exposure to the magnetic field is repeated many times and as a result, a layer-by-layer image of the subject’s brain is created on the computer.

Rheoencephalography

Rheoencephalography is a method for studying the blood circulation of the human brain, based on recording changes in the resistance of brain tissue to high-frequency alternating current depending on the blood supply and allows one to indirectly judge the amount of total blood supply to the brain, the tone, elasticity of its vessels and the state of venous outflow.

Echoencephalography

The method is based on the property of ultrasound to be reflected differently from brain structures, cerebrospinal fluid, skull bones, and pathological formations. In addition to determining the size of the localization of certain brain formations, this method allows you to estimate the speed and direction of blood flow.

Study of the functional state of the human autonomic nervous system

The study of the functional state of the ANS is of great diagnostic importance in clinical practice. The tone of the ANS is judged by the state of reflexes, as well as by the results of a number of special functional tests. Methods for clinical research of VNS are conditionally divided into the following groups:

• Patient interview;
• Study of dermographism (white, red, elevated, reflex);
• Study of vegetative pain points;
• Cardiovascular tests (capillaroscopy, adrenaline and histamine skin tests, oscillography, plethysmography, determination of skin temperature, etc.);
• Electrophysiological tests – study of electro-skin resistance using a direct current apparatus;
• Determination of the content of biologically active substances, for example catecholamines in urine and blood, determination of blood cholinesterase activity.



Methods for directly studying the functions of the central nervous system are divided into morphological and functional.

Morphological methods- macroanatomical and microscopic studies of the structure of the brain. This principle underlies the method of genetic mapping of the brain, which allows us to identify the functions of genes in neuronal metabolism. Morphological methods also include the method of labeled atoms. Its essence lies in the fact that radioactive substances introduced into the body penetrate more intensively into those nerve cells of the brain that are currently most functionally active.

Functional methods: destruction and irritation of central nervous system structures, stereotactic method, electrophysiological methods.

Destruction method. Destruction of brain structures is a rather crude method of research, since large areas of brain tissue are damaged. In the clinic, to diagnose brain damage of various origins (tumors, stroke, etc.) in humans, methods of computed x-ray tomography, echoencephalography, and nuclear magnetic resonance are used.

Irritation method brain structures makes it possible to establish the paths of excitation propagation from the place of irritation to the organ or tissue, the function of which changes in this case. Electric current is most often used as an irritating factor. In experiments on animals, a method of self-irritation of various parts of the brain is used: the animal is able to send irritation to the brain, closing the electric current circuit, and stop the irritation by opening the circuit.

Stereotactic method of electrode insertion.

Stereotactic atlases, which have three coordinate values ​​for all brain structures placed in the space of three mutually perpendicular planes - horizontal, sagittal and frontal. This method allows not only to insert electrodes into the brain with high precision for experimental and diagnostic purposes, but also to specifically influence individual structures with ultrasound, laser or X-ray beams for therapeutic purposes, as well as to perform neurosurgical operations.

Electrophysiological methods CNS studies include analysis of both passive and active electrical properties of the brain.

Electroencephalography. The method of recording the total electrical activity of the brain is called electroencephalography, and the curve of changes in brain biopotentials is called an electroencephalogram (EEG). EEG is recorded using electrodes placed on the surface of a person's head. Two methods of recording biopotentials are used: bipolar and monopolar. With the bipolar method, the difference in electrical potential between two closely located points on the surface of the head is recorded. With the monopolar method, the difference in electrical potential is recorded between any point on the surface of the head and an indifferent point on the head, whose own potential is close to zero. Such points are the earlobes, the tip of the nose, and the surface of the cheeks. The main indicators characterizing the EEG are the frequency and amplitude of biopotential oscillations, as well as the phase and shape of the oscillations. Based on the frequency and amplitude of oscillations, several types of rhythms in the EEG are distinguished.

2. Gamma >35 Hz, emotional arousal, mental and physical activity, when irritating.

3. Beta 13-30 Hz, emotional arousal, mental and physical activity, when causing irritation.

4. Alpha 8-13 Hz state of mental and physical rest, with eyes closed.

5. Theta 4-8 Hz, sleep, moderate hypoxia, anesthesia.

6. Delta 0.5 – 3.5 deep sleep, anesthesia, hypoxia.

7. The main and most characteristic rhythm is the alpha rhythm. In a state of relative rest, the alpha rhythm is most pronounced in the occipital, occipito-temporal and occipito-parietal regions of the brain. With short-term exposure to stimuli, such as light or sound, the beta rhythm appears. Beta and gamma rhythms reflect the activated state of brain structures, the theta rhythm is more often associated with the emotional state of the body. The delta rhythm indicates a decrease in the functional level of the cerebral cortex, associated, for example, with a state of light sleep or fatigue. The local appearance of a delta rhythm in any area of ​​the cerebral cortex indicates the presence of a pathological focus in it.

Microelectrode method. Registration of electrical processes in individual nerve cells. Microelectrodes - glass or metal. Glass micropipettes are filled with an electrolyte solution, most often a concentrated solution of sodium or potassium chloride. There are two ways to record cellular electrical activity: intracellular and extracellular. At intracellular At the location of the microelectrode, the membrane potential, or resting potential of the neuron, postsynaptic potentials - excitatory and inhibitory, as well as the action potential are recorded. Extracellular microelectrode registers only the positive part of the action potential.

2. Electrical activity of the cerebral cortex, electroencephalography.

EEG IN THE FIRST QUESTION!

Functional significance of various structures of the central nervous system.

The main reflex centers of the nervous system.

Spinal cord.

The distribution of functions of incoming and outgoing fibers of the spinal cord obeys a certain law: all sensory (afferent) fibers enter the spinal cord through its dorsal roots, and motor and autonomic (efferent) fibers exit through the anterior roots. Posterior roots formed by the fibers of one of the processes of afferent neurons, the bodies of which are located in the intervertebral ganglia, and the fibers of the other process are associated with the receptor. Anterior roots consist of processes of motor neurons of the anterior horns of the spinal cord and neurons of the lateral horns. The fibers of the former are directed to the skeletal muscles, while the fibers of the latter are switched in the autonomic ganglia to other neurons and innervate the internal organs.

Spinal cord reflexes can be divided into motor, carried out by alpha motor neurons of the anterior horns, and vegetative, carried out by efferent cells of the lateral horns. Motor neurons of the spinal cord innervate all skeletal muscles (with the exception of the facial muscles). The spinal cord carries out elementary motor reflexes - flexion and extension, arising from irritation of skin receptors or proprioceptors of muscles and tendons, and also sends constant impulses to the muscles, maintaining their tension - muscle tone. Muscle tone occurs as a result of irritation of proprioceptors in muscles and tendons when they are stretched during human movement or when exposed to gravity. Impulses from proprioceptors enter the motor neurons of the spinal cord, and impulses from the motor neurons are sent to the muscles, maintaining their tone.

Medulla oblongata and pons. The medulla oblongata and the pons are classified as the hindbrain. It is part of the brain stem. The hindbrain carries out complex reflex activity and serves to connect the spinal cord with the overlying parts of the brain. In its middle region are the posterior sections of the reticular formation, which exert nonspecific inhibitory effects on the spinal cord and brain.

Pass through the medulla oblongata ascending pathways from auditory and vestibular sensitivity receptors. End in the medulla oblongata afferent nerves carrying information from skin receptors and muscle receptors.

, Midbrain. Through the midbrain, which is a continuation of the brain stem, ascending pathways pass from the spinal cord and medulla oblongata to the thalamus, cerebral cortex and cerebellum.

Diencephalon. The diencephalon, which is the anterior end of the brain stem, includes visual hillocks - thalamus and subthalamic region - hypothalamus.

Thalamus represents the most important “station” on the path of afferent impulses to the cerebral cortex.

Thalamic nuclei divided into specific and nonspecific.

Subcortical nodes. Through subcortical nuclei Different parts of the cerebral cortex can connect with each other, which is of great importance in the formation of conditioned reflexes. Together with the diencephalon, the subcortical nuclei are involved in the implementation of complex unconditioned reflexes: defensive, food, etc.

Cerebellum. This - suprasegmental formation, not having a direct connection with the executive apparatus. The cerebellum is part of the extrapyramidal system. It consists of two hemispheres and a worm located between them. The outer surfaces of the hemispheres are covered with gray matter - cerebellar cortex, and accumulations of gray matter in white matter form cerebellar nuclei.

FUNCTIONS OF THE SPINAL CORD

The first function is reflexive. The spinal cord carries out motor reflexes of skeletal muscles relatively independently
Thanks to reflexes from proprioceptors in the spinal cord, motor and autonomic reflexes are coordinated. Reflexes are also carried out through the spinal cord from internal organs to skeletal muscles, from internal organs to receptors and other organs of the skin, from an internal organ to another internal organ.

The second function is conductive. Centripetal impulses entering the spinal cord along the dorsal roots are transmitted along short pathways to its other segments, and along long pathways to different parts of the brain.

The main long pathways are the following ascending and descending pathways.

Ascending paths of the posterior pillars. 1. Gentle bundle (Gaulle), conducting impulses to the diencephalon and cerebral hemispheres from skin receptors (touch, pressure), interoreceptors and proprioceptors of the lower torso and legs. 2. Wedge-shaped bundle (Burdacha), which conducts impulses to the diencephalon and cerebral hemispheres from the same receptors of the upper torso and arms.

Ascending paths of side pillars. 3. Posterior spinocerebellar (Flexiga) and 4. Anterior spinocerebellar (Goversa), conducting impulses from the same receptors to the cerebellum. 5. Spino-thalamic, conducting impulses to the diencephalon from skin receptors - touch, pressure, pain and temperature, and from interoreceptors.

Descending tracts from the brain to the spinal cord.
1. Direct pyramidal, or anterior corticospinal fasciculus, from neurons of the anterior central gyrus of the frontal lobes of the cerebral hemispheres to neurons of the anterior horns of the spinal cord; crosses in the spinal cord. 2. Crossed pyramidal, or corticospinal lateral fasciculus, from neurons of the frontal lobes of the cerebral hemispheres to neurons of the anterior horns of the spinal cord; decussates in the medulla oblongata. Along these bundles, which reach the greatest development in humans, voluntary movements are carried out in which behavior is manifested. 3. The rubrospinal fasciculus (Monakova) conducts centrifugal impulses from the red nucleus of the midbrain into the spinal cord, regulating the tone of skeletal muscles. 4. The vestibulospinal fascicle conducts from the vestibular apparatus to the spinal cord through the medulla oblongata and medial impulses, redistributing the tone of skeletal muscles

Cerebrospinal fluid formation

In the subarachnoid (subarachnoid) space there is cerebrospinal fluid, which in composition is a modified tissue fluid. This fluid acts as a shock absorber for brain tissue. It is also distributed along the entire length of the spinal canal and in the ventricles of the brain. Cerebrospinal fluid is secreted into the ventricles of the brain from the choroid plexuses, formed by numerous capillaries extending from the arterioles and hanging in the form of tassels into the ventricular cavity

The surface of the plexus is covered with single-layer cubic epithelium, developing from the ependyma of the neural tube. Beneath the epithelium lies a thin layer of connective tissue that arises from the pia and arachnoid membranes of the brain.

Cerebrospinal fluid is also formed by blood vessels that penetrate the brain. The amount of this fluid is insignificant; it is released onto the surface of the brain along the soft membrane accompanying the vessels.

Midbrain.

The midbrain includes the cerebral peduncles, located ventrally, and the roof plate (lamina tecti), or quadrigemina, lying dorsally. The cavity of the midbrain is the cerebral aqueduct. The roof plate consists of two superior and two inferior colliculi, which contain the nuclei of gray matter. The superior colliculi are associated with the visual pathway, the inferior colliculi with the auditory pathway. From them originates the motor pathway that goes to the cells of the anterior horns of the spinal cord. A cross section of the midbrain clearly shows its three sections: the roof, the tegmentum and the base of the cerebral peduncle. Between the tire and the base is a black substance. The tegmentum contains two large nuclei - the red nuclei and the nuclei of the reticular formation. The cerebral aqueduct is surrounded by central gray matter, which contains the nuclei of the III and IV pairs of cranial nerves. The base of the cerebral peduncles is formed by fibers of the pyramidal tracts and tracts connecting the cerebral cortex with the nuclei of the bridge and the cerebellum. The tegmentum contains systems of ascending pathways that form a bundle called the medial (sensitive) loop. The fibers of the medial lemniscus begin in the medulla oblongata from the cells of the nuclei of the thin and cuneate fasciculi and end in the nuclei of the thalamus. The lateral (auditory) loop consists of fibers of the auditory tract running from the pons to the inferior colliculi of the pontine tegmentum (quadrigeminal) and the medial geniculate bodies of the diencephalon.

Physiology of the midbrain

The midbrain plays an important role in regulating muscle tone and implementing the righting and righting reflexes, which make standing and walking possible.

The role of the midbrain in the regulation of muscle tone is best observed in a cat in which a transverse incision is made between the medulla oblongata and the midbrain. Such a cat has a sharp increase in muscle tone, especially extensor muscles. The head is thrown back, the paws are sharply straightened. The muscles are so strongly contracted that an attempt to bend the limb ends in failure - it immediately straightens. An animal placed on outstretched paws like sticks can stand. This condition is called decerebrate rigidity. If the incision is made above the midbrain, then decerebrate rigidity does not occur. After about 2 hours, such a cat makes an effort to get up. First she raises her head, then her body, then stands on her paws and can begin to walk. Consequently, the nervous apparatus for regulating muscle tone and the functions of standing and walking are located in the midbrain.

The phenomena of decerebrate rigidity are explained by the fact that the red nuclei and reticular formation are separated from the medulla oblongata and spinal cord by transection. The red nuclei do not have a direct connection with receptors and effectors, but they are connected with all parts of the central nervous system. They are approached by nerve fibers from the cerebellum, basal ganglia, and cerebral cortex. The descending rubrospinal tract begins from the red nuclei, through which impulses are transmitted to the motor neurons of the spinal cord. It is called the extrapyramidal tract.

The sensitive nuclei of the midbrain perform a number of important reflex functions. The nuclei located in the superior colliculi are the primary visual centers. They receive impulses from the retina and participate in the orientation reflex, i.e. turning the head towards the light. At the same time, the width of the pupil and the curvature of the lens (accommodation) change, which contributes to clear vision of the object. The nuclei of the inferior colliculi are the primary auditory centers. They participate in the orienting reflex to sound - turning the head towards the sound. Sudden sound and light stimulation cause a complex alarm reaction (start reflex), mobilizing the animal for a quick response.

Cerebellum.

Physiology of the cerebellum

The cerebellum is located above the segmental part of the central nervous system, which does not have a direct connection with the receptors and effectors of the body. It is connected in numerous ways to all parts of the central nervous system. Afferent pathways are sent to it, carrying impulses from proprioceptors of muscles, tendons, vestibular nuclei of the medulla oblongata, subcortical nuclei and cerebral cortex. In turn, the cerebellum sends impulses to all parts of the central nervous system.

The functions of the cerebellum are studied by irritating it, partially or completely removing it, and studying bioelectrical phenomena. The Italian physiologist Luciani characterized the consequences of removal of the cerebellum and loss of its functions with the famous triad A: astasia, atony and asthenia. Subsequent researchers added another symptom - ataxia.

A dog without a cerebellum stands on widely spaced legs and makes continuous rocking movements (astasia). She has impaired proper distribution of flexor and extensor muscle tone (atony). Movements are poorly coordinated, sweeping, disproportionate, abrupt. When walking, the paws are thrown beyond the midline (ataxia), which is not observed in normal animals. Ataxia is explained by the fact that movement control is impaired. Analysis of signals from proprioceptors of muscles and tendons is missing. The dog cannot get its muzzle into the food bowl. Tilt of the head downwards or to the side causes a strong opposite movement.

The movements are very tiring: the animal, after walking a few steps, lies down and rests. This symptom is called asthenia.

Over time, movement disorders in dogs without a cerebellum smooth out. She eats on her own and her gait is almost normal. Only biased observation reveals some violations (compensation phase).

As shown by E.A. Asratyan, compensation of functions occurs due to the cerebral cortex. If the bark of such a dog is removed, then all the violations are revealed again and are never compensated.

The cerebellum is involved in the regulation of movements, making them smooth, precise, proportionate. In the figurative expression of L.A. Orbeli, the cerebellum is an assistant to the cerebral cortex in controlling skeletal muscles and the activity of autonomic organs. As studies by L.A. have shown. Orbeli, autonomic functions are impaired in dogs without cerebellar systems. Blood constants, vascular tone, the functioning of the digestive tract and other autonomic functions become very unstable and easily shift under the influence of certain reasons (food intake, muscle work, temperature changes, etc.).

When half of the cerebellum is removed, motor functions on the side of the operation are impaired. This is explained by the fact; that the cerebellar pathways either do not cross at all or cross twice.

Diencephalon.

Diencephalon

The diencephalon is located under the corpus callosum and fornix, fused on the sides with the cerebral hemispheres. It includes the thalamus (visual thalamus), epithalamus (above the thalamic region), metathalamus (the sub-tubercular “region”) and the hypothalamus (under the tubercular region). The cavity of the diencephalon is the third ventricle.

The thalamus is a paired, ovoid collection of gray matter covered by a layer of white matter. The anterior sections are adjacent to the interventricular foramina, the posterior sections are expanded - to the quadrigeminal. The lateral surfaces of the thalamus grow together with the hemispheres and border the caudate nucleus and the internal capsule. The medial surfaces form the walls of the third ventricle, the lower ones continue into the hypothalamus. In the thalamus, there are three main groups of nuclei: anterior, lateral and medial, and there are 40 nuclei in total. In the epithalamus lies the upper appendage of the brain - the pineal gland, or pineal body, suspended on two leashes in the recess between the upper colliculi of the roof plate. The metathalamus is represented by the medial and lateral geniculate bodies, connected by bundles of fibers (handles of the colliculi) with the superior (lateral) and inferior (medial) colliculi of the roof plate. They contain nuclei that are reflex centers of vision and hearing.

The hypothalamus is located ventral to the thalamus and includes the subtubercular region itself and a number of formations located at the base of the brain. These include: the terminal plate, the optic chiasm, the gray tubercle, the infundibulum with the lower appendage of the brain extending from it - the pituitary gland and the mastoid bodies. In the hypothalamic region there are nuclei (supra optic, periventricular, etc.) containing large nerve cells capable of secreting a secretion (neurosecretion) that flows along their axons into the posterior lobe of the pituitary gland and then into the blood. In the posterior part of the hypothalamus lie nuclei formed by small nerve cells, which are connected to the anterior lobe of the pituitary gland by a special system of blood vessels.

The third (III) ventricle is located in the midline and is a narrow vertical slit. Its lateral walls are formed by the medial surfaces of the thalami and under the tubercular region, the anterior - by the columns of the fornix and the anterior commissure, the lower - by the formations of the hypothalamus and the posterior - by the cerebral peduncles and above the tubercular region. The upper wall - the lid of the third ventricle - is the thinnest and consists of the soft membrane of the brain, lined on the side of the ventricular cavity with an epithelial plate (ependyma). The soft shell has a large number of blood vessels here, forming the choroid plexus. In front, the third ventricle communicates with the lateral ventricles (I-II) through the interventricular foramina, and behind it passes into the aqueduct

Physiology of the diencephalon

The thalamus is a sensitive subcortical nucleus. It is called the “collector of sensitivity”, since afferent pathways from all receptors converge to it, excluding olfactory ones. In the lateral nuclei of the thalamus there is a third neuron of the afferent pathways, the processes of which end in the sensitive zones of the cerebral cortex.

The main functions of the thalamus are integration (unification) of all types of sensitivity, comparison of information received through various communication channels, and assessment of its biological significance. The nuclei of the thalamus are divided according to their function into specific (the ascending afferent pathways end on the neurons of these nuclei), nonspecific (nuclei of the reticular formation) and associative. Through the associative nuclei, the thalamus is connected with all the motor subcortical nuclei: the striatum, the globus pallidus, the hypothalamus - and with the nuclei of the midbrain and medulla oblongata.

The study of the functions of the thalamus is carried out by cutting, irritation and destruction. A cat in which the incision is made above the diencephalon is very different from a cat in which the highest part of the central nervous system is the midbrain. She not only gets up and walks, that is, performs complexly coordinated movements, but also shows all the signs of emotional reactions. A light touch causes an angry reaction: the cat whips its tail, bares its teeth, growls, bites, and extends its claws. In humans, the thalamus plays a significant role in emotional behavior, characterized by peculiar facial expressions, gestures and shifts in the functions of internal organs. During emotional reactions, blood pressure rises, pulse and breathing quicken, and pupils dilate. The facial reaction of a person is innate. If you tickle the nose of a 5-6 month old fetus, you can see a typical grimace of displeasure (P.K. Anokhin). In animals, when the thalamus is irritated, motor and pain reactions occur: squealing, grumbling. The effect can be explained by the fact that impulses from the visual thalamus easily transfer to the associated motor subcortical nuclei.

In the clinic, symptoms of damage to the thalamus are severe headache, sleep disturbances, disturbances in sensitivity (increased or decreased), movements, their accuracy, proportionality, and the occurrence of violent involuntary movements.

The hypothalamus is the highest subcortical center of the autonomic nervous system. In this area there are centers that regulate all vegetative functions, ensuring the constancy of the internal environment of the body, as well as regulating fat, protein, carbohydrate and water-salt metabolism. In the activity of the autonomic nervous system, the hypothalamus plays the same important role as the red nuclei of the midbrain play in the regulation of skeletal-motor functions of the somatic nervous system.

The earliest studies of the function of the hypothalamus belong to Claude Bernard. He discovered that an injection into the diencephalon of a rabbit caused an increase in body temperature of almost 3°C. This classic experiment, which made it possible to discover the thermoregulation center in the hypothalamus, was called heat injection. After the destruction of the hypothalamus, the animal becomes poikilothermic, that is, it loses the ability to maintain a constant body temperature.

It was later discovered that almost all organs innervated by the autonomic nervous system can be activated by stimulation of the subtubercular region. In other words, all the effects that can be obtained by irritating the sympathetic and parasympathetic nerves are observed when irritating the hypothalamus.

Currently, the method of implanting electrodes is widely used to stimulate various brain structures. Using a special, so-called stereotaxic technique, electrodes are inserted into any given area of ​​the brain through a burr hole in the skull. The electrodes are insulated throughout, only their tip is free. By connecting electrodes in a circuit, you can locally irritate certain areas.

When the anterior parts of the hypothalamus are irritated, parasympathetic effects occur: increased intestinal movements, separation of digestive juices, slowing down heart contractions, etc.; when the posterior sections are irritated, sympathetic effects are observed: increased heart rate, constriction of blood vessels, increased body temperature, etc. Consequently, parasympathetic centers are located in the anterior sections of the hypothalamus, and sympathetic centers in the posterior sections.

Since stimulation with the help of implanted electrodes is carried out on the animal without anesthesia, it is possible to judge the behavior of the animal. In Andersen's experiments on a goat with implanted electrodes, a center was discovered, the irritation of which causes unquenchable thirst - the thirst center. When irritated, the goat could drink up to 10 liters of water. By stimulating other areas, it was possible to force a well-fed animal to eat (hunger center).

The experiments of the Spanish scientist Delgado on a bull became widely known. An electrode was implanted into the bull's fear center. When an angry bull rushed at a bullfighter in the arena, the irritation was turned on and the bull retreated with clearly expressed signs of fear.

American researcher D. Olds proposed modifying the method: allowing the animal itself to make contact (self-irritation method). He believed that the animal would avoid unpleasant stimuli and, on the contrary, would strive to repeat pleasant ones. Experiments have shown that there are structures whose irritation causes an uncontrollable desire to repeat. The rats worked themselves to the point of exhaustion by pressing the lever up to 14,000 times. In addition, structures were discovered whose irritation apparently causes an unpleasant sensation, since the rat avoids pressing the lever a second time and runs away from it. The first center is obviously the center of pleasure, the second is the center of displeasure.

Extremely important for understanding the functions of the hypothalamus was the discovery in this part of the brain of receptors that detect changes in blood temperature (thermoreceptors), osmotic pressure (osmoreceptors) and blood composition (glucoreceptors).

Reflexes arise from receptors “turned into the blood” aimed at maintaining the constancy of the internal environment of the body - homeostasis. “Hungry” blood, irritating glucoreceptors, excites the food center: food reactions arise, aimed at searching and eating food.

One of the common manifestations of hypothalamic disease is a violation of water-salt metabolism, manifested in the release of large amounts of low-density urine. The disease is called diabetes insipidus.

The subtuberous region is closely related to the activity of the pituitary gland. The hormones vasopressin and oxytocin are produced in large neurons of the supra-optic and paraventricular nuclei of the hypothalamus. Hormones travel along axons to the posterior lobe of the pituitary gland, where they accumulate and then enter the blood.

A different relationship between the hypothalamus and the anterior pituitary gland. The vessels surrounding the nuclei of the hypothalamus unite into a system of veins, which reach the anterior lobe of the pituitary gland and here again break up into capillaries. With the blood, releasing factors, or releasing factors, enter the pituitary gland, stimulating the formation of hormones in its anterior lobe.

17. Subcortical centers .

18. Cerebral cortex.

General plan of the organization bark. The cerebral cortex is the highest section of the central nervous system, which appears later in the process of phylogenetic development and is formed during individual (ontogenetic) development later than other parts of the brain. The cortex is a layer of gray matter 2-3 mm thick, containing on average about 14 billion (from 10 to 18 billion) nerve cells, nerve fibers and interstitial tissue (neuroglia). In its cross section, 6 horizontal layers are distinguished based on the location of neurons and their connections. Thanks to numerous convolutions and grooves, the surface area of ​​the cortex reaches 0.2 m2. Directly below the cortex is white matter, consisting of nerve fibers that transmit excitation to and from the cortex, as well as from one area of ​​the cortex to another.

Cortical neurons and their connections. Despite the huge number of neurons in the cortex, very few of their varieties are known. Their main types are pyramidal and stellate neurons. Which do not differ in functional mechanism.

In the afferent function of the cortex and in the processes of switching excitation to neighboring neurons, the main role belongs to stellate neurons. They make up more than half of all cortical cells in humans. These cells have short branching axons that do not extend beyond the gray matter of the cortex, and short branching dendrites. Stellate neurons are involved in the processes of perception of irritation and combining the activities of various pyramidal neurons.

Pyramidal neurons carry out the efferent function of the cortex and intracortical processes of interaction between neurons remote from each other. They are divided into large pyramids, from which projection, or efferent, paths to subcortical formations begin, and small pyramids, forming associative paths to other parts of the cortex. The largest pyramidal cells - the giant pyramids of Betz - are located in the anterior central gyrus, in the so-called motor zone of the cortex. A characteristic feature of large pyramids is their vertical orientation within the crust. From the cell body, the thickest (apical) dendrite is directed vertically upward to the surface of the cortex, through which various afferent influences from other neurons enter the cell, and the efferent process, the axon, extends vertically downward.

The cerebral cortex is characterized by an abundance of interneuron connections. As the human brain develops after birth, the number of intercentral connections increases, especially intensely until the age of 18.

The functional unit of the cortex is a vertical column of interconnected neurons. Large pyramidal cells elongated vertically with neurons located above and below them form functional associations of neurons. All neurons of the vertical column respond to the same afferent stimulation (from the same receptor) with the same reaction and jointly form the efferent responses of pyramidal neurons.

The spread of excitation in the transverse direction - from one vertical column to another - is limited by inhibition processes. The occurrence of activity in the vertical column leads to the excitation of spinal motor neurons and contraction of the muscles associated with them. This path is used, in particular, for voluntary control of limb movements.

Primary, secondary and tertiary fields of the cortex. The structural features and functional significance of individual areas of the cortex make it possible to distinguish individual cortical fields.

There are three main groups of fields in the cortex: primary, secondary and tertiary fields.

Primary fields are associated with sensory organs and organs of movement on the periphery; they mature earlier than others in ontogenesis and have the largest cells. These are the so-called nuclear zones of the analyzers, according to I. P. Pavlov (for example, the field of pain, temperature, tactile and muscle-articular sensitivity in the posterior central gyrus of the cortex, the visual field in the occipital region, the auditory field in the temporal region and the motor field in the anterior central gyrus of the cortex) (Fig. 54). These fields analyze individual stimuli entering the cortex from the corresponding receptors. When primary fields are destroyed, so-called cortical blindness, cortical deafness, etc. occur. Nearby are secondary fields, or peripheral zones of analyzers, which are connected to individual organs only through primary fields. They serve to summarize and further process incoming information. Individual sensations are synthesized in them into complexes that determine the processes of perception. When secondary fields are damaged, the ability to see objects and hear sounds is retained, but the person does not recognize them and does not remember their meaning. Both humans and animals have primary and secondary fields.

The furthest from direct connections with the periphery are the tertiary fields, or the overlap zones of the analyzers. Only humans have these fields. They occupy almost half of the cortex and have extensive connections with other parts of the cortex and with nonspecific brain systems. These fields are dominated by the smallest and most diverse cells. The main cellular element here are stellate neurons. Tertiary fields are located in the posterior half of the cortex - at the boundaries of the parietal, temporal and occipital regions and in the anterior half - in the anterior parts of the frontal regions. These zones contain the largest number of nerve fibers connecting the left and right hemispheres, so their role is especially important in organizing the coordinated work of both hemispheres. Tertiary fields mature in humans later than other cortical fields; they carry out the most complex functions of the cortex. Processes of higher analysis and synthesis take place here. In tertiary fields, based on the synthesis of all afferent stimuli and taking into account traces of previous stimuli, goals and objectives of behavior are developed. According to them, motor activity is programmed. The development of tertiary fields in humans is associated with the function of speech. Thinking (inner speech) is possible only with the joint activity of analyzers, the integration of information from which occurs in tertiary fields.

Basic methods for studying the functions of the central nervous system in humans.

Methods for studying the functions of the central nervous system are divided into two groups: 1) direct study and 2) indirect (indirect) study.

Lesson 1. General physiology of the central nervous system. Reflex principles of regulation of functions.

Questions for self-study.

1. The nervous system and its significance. General characteristics of the structure and functions of the central nervous system.

2. Methods for studying the central nervous system.

3. Reflex theory and the main stages of its formation. Principles of reflex activity.

4. Conceptual reflex arc. Basic elements of the reflex arc. Structural features of simple and complex reflex arcs. Reflex ring.

5. Classification of reflexes. Levels of organization of reflex reactions.

6. General properties of reflexes.

Basic information.

The emergence of multicellular organisms was the initial stimulus for the differentiation of cells and the specialization of some of these cells into communication systems, which ultimately led to the formation of the most complex nervous system of mammals and humans. Nervous system regulates the activity of all organs and systems, determining their functional unity, and ensures the connection of the body as a whole with the external environment.

The nervous system is conventionally divided into two large sections - somatic, or animal, nervous system and vegetative, or autonomic nervous system.

The somatic nervous system primarily carries out the functions of connecting the body with the external environment, providing sensitivity and movement causing contraction of skeletal muscles. Since the functions of movement and feeling are characteristic of animals and distinguish them from plants, this part of the nervous system is called animal (animal).

The autonomic nervous system influences the processes of so-called plant life, common to animals and plants (metabolism, respiration, excretion, etc.), which is where its name comes from (vegetative - plant). Both systems are closely related to each other, but the autonomic nervous system has a certain degree of independence and does not depend on our will, as a result of which it is also called the autonomic nervous system. It is divided into two parts sympathetic And parasympathetic.

The nervous system is divided into a central part - the brain and spinal cord - the central nervous system and a peripheral part, represented by nerves extending from the brain and spinal cord - the peripheral nervous system. A cross-section of the brain shows that it consists of gray and white matter.

Gray matter is formed by clusters of nerve cells (with the initial sections of processes extending from their bodies). Individual limited accumulations of gray matter are called nuclei.
White matter form nerve fibers covered with a myelin sheath (the processes of nerve cells that form the gray matter). Nerve fibers in the brain and spinal cord form pathways

Peripheral nerves, depending on what fibers (sensory or motor) they consist of, are divided into sensory, motor and mixed. The cell bodies of the neurons, the processes of which make up the sensory nerves, lie in the ganglia outside the brain. The cell bodies of motor neurons lie in the anterior horns of the spinal cord or motor nuclei of the brain.

central nervous system(CNS) is a part of the nervous system, including the brain and spinal cord, which perform a number of complex functions in the human and animal body.

Brain activity aimed at performing these functions can be divided into five main categories:

• feeling- arising in the nervous system as a result of perception by the senses of changes in the external environment;
• movement- changes in the state of the body’s muscles that occur under the influence of signals from the nervous system;
• internal regulation- regulation of the work of internal organs depending on the state of the external or internal environment;
• regulation of procreation– control of hormonal regulation of the reproductive functions of the body, as well as regulation of sexual behavior;
• adaptation- ensuring the body’s adaptation to changing environmental conditions.

I.P. Pavlov showed that the central nervous system can have three types of effects on organs:

- launcher causing or stopping the function of an organ (muscle contraction, gland secretion);

- vasomotor, changing the width of the lumen of blood vessels and thereby regulating the flow of blood to the organ;

- trophic, increasing or decreasing metabolism and therefore the consumption of nutrients and oxygen. Thanks to this, the functional state of the organ and its need for nutrients and oxygen are constantly coordinated. When impulses are sent to the working skeletal muscle through motor fibers, causing its contraction, then simultaneously impulses are sent through the autonomic nerve fibers, dilating blood vessels and increasing metabolism. This ensures the energetic ability to perform muscle work.

The central nervous system perceives afferent(sensitive) information arising from stimulation of specific receptors, and in response to this forms the corresponding efferent impulses that cause changes in the activity of certain organs and systems of the body.

Analysis of the functions of the central nervous system allows us to formulate importance of the central nervous system:

1. The central nervous system provides mutual connection of individual organs and systems, coordinates and combines their functions. Thanks to this, the body works as a single whole. Accurate control over the functioning of internal organs is achieved by the existence of a two-way circular connection between the central nervous system and peripheral organs.

2. The central nervous system carries out organism interaction,as a whole, with the external environment, as well as individual adaptation to the external environment - behavior. This type of activity based on innate mechanisms is called lower nervous activity (instincts), and on acquired ones - higher nervous activity (conditioned reflexes).

3. The brain is an organ mental activity. As a result of the entry of nerve impulses into the cells of the cerebral cortex, sensations arise and, on their basis, specific qualities of highly organized matter appear - the processes of consciousness and thinking. Mental activity is an ideal, subjectively conscious activity of the body carried out with the help of neurophysiological processes. That is, mental activity is realized with the help of GNI, but is not it.

Methods for studying the functions of the central nervous system.

The intensive development of the physiology of the central nervous system has led to a transition from descriptive methods of studying the functions of various parts of the brain to experimental methods. Many methods used to study CNS function are used in combination with each other.

Destruction method(experimentation) of various parts of the central nervous system. Using this method, it is possible to establish which functions of the central nervous system are lost after surgery and which are preserved. This methodological technique has long been used in experimental physiological research.

cutting method, makes it possible to study the significance in the activity of one or another department of the central nervous system of influences coming from its other departments. Transection is performed at various levels of the central nervous system. Complete transection, for example, of the spinal cord or brain stem separates the overlying parts of the central nervous system from the underlying ones and makes it possible to study reflex reactions that are carried out by nerve centers located below the transection site. Transection and local damage to individual nerve centers is performed not only under experimental conditions, but also in a neurosurgical clinic as a therapeutic measure.

Irritation method allows you to study the functional significance of various formations of the central nervous system. With stimulation (chemical, electrical, mechanical, etc.) of certain brain structures, one can observe the emergence, features of manifestation and the nature of the spread of excitation processes.

Electroencephalography is a method of recording the total electrical activity of various parts of the brain. For the first time, recording of the electrical activity of the brain was carried out by V. V. Pravdich-Neminsky using electrodes immersed in the brain. Berger recorded brain potentials from the surface of the skull and called the recording of brain potential oscillations electroencephalogram(EEG-ma).

The frequency and amplitude of oscillations can change, but at each moment in time certain rhythms predominate in the EEG, which Berger called alpha, beta, theta and delta rhythms. Alpha rhythm characterized by an oscillation frequency of 8-13 Hz, amplitude 50 μV. This rhythm is best expressed in the occipital and parietal areas of the cortex and is recorded under conditions of physical and mental rest with eyes closed. If you open your eyes, the alpha rhythm is replaced by a faster beta rhythm. Beta rhythm characterized by an oscillation frequency of 14-50 Hz and an amplitude of up to 25 μV. Some people do not have an alpha rhythm and therefore register a beta rhythm at rest. In this regard, beta rhythm 1 is distinguished with an oscillation frequency of 16-20 Hz; it is characteristic of a state of rest and is recorded in the frontal and parietal regions. Beta rhythm 2 with a frequency of 20-50 Hz and is characteristic of a state of intense brain activity. Theta rhythm represents oscillations with a frequency of 4-8 Hz and an amplitude of 100-150 μV. This rhythm is recorded in the temporal and parietal regions during psychomotor activity, stress, sleep, hypoxia and light anesthesia. Delta rhythm characterized by slow oscillations of potentials with a frequency of 0.5-3.5 Hz, an amplitude of 250-300 μV. This rhythm is recorded during deep sleep, during deep anesthesia, and during hypoxia.

EEG method used in the clinic for diagnostic purposes. This method has found particularly wide application in neurosurgical clinics to determine the location of brain tumors. In a neurological clinic, this method is used to determine the localization of an epileptic focus, and in a psychiatric clinic, for diagnosing mental disorders. In the surgical clinic, EEG is used to test the depth of anesthesia.

Evoked potential method- registration of electrical activity of certain brain structures when stimulating receptors, nerves, and subcortical structures. Evoked potentials (EPs) most often represent three-phase EEG oscillations, replacing each other: positive, negative, and a second (later) positive oscillation. However, they can also have a more complex shape. There are primary (PO) and late or secondary (SE) evoked potentials. An EP is a fragment of an EEG recorded at the time of brain stimulation and is of the same nature as an electroencephalogram.

The VP method is used in neurology and neurophysiology. Using VP, you can trace the ontogenetic development of the brain pathways, analyze the localization of the representation of sensory functions, analyze the connections between brain structures, show the number of switches along the path of excitation, etc.

Microelectrode method used to study the physiology of an individual neuron, its bioelectrical activity both at rest and under various influences. For these purposes, specially made glass or metal microelectrodes are used, the tip diameter of which is 0.5-1.0 microns or slightly more. Glass microelectrodes are micropipettes filled with an electrolyte solution. Depending on the location of the microelectrode, there are two ways to remove the bioelectrical activity of cells - intracellular and extracellular.

Intracellular lead allows you to record and measure:

Resting membrane potential;

Postsynaptic potentials (EPSP and IPSP);

Dynamics of the transition of local excitation to propagating;

Action potential and its components.

Extracellular lead makes it possible to register:

Spike activity of both individual neurons and, mainly, their groups located around the electrode.

For precise determination of the position of various brain structures and for introducing various micro-objects into them (electrodes, thermocouples, pipettes, etc.), it has found wide application both in electrophysiological studies and in the neurosurgical clinic. stereotactic method. Its use is based on the results of detailed anatomical studies of the location of various brain structures relative to the bony landmarks of the skull. Based on the data from such studies, special stereotactic atlases have been created for both various animal species and humans. Currently, the stereotactic method is widely used in neurosurgical clinics for the following purposes:

Destruction of brain structures in order to eliminate states of hyperkinesis, indomitable pain, some mental disorders, epileptic disorders, etc.;

Identification of pathological epileptogenic foci;

Injecting radioactive substances into brain tumors and destroying these tumors;

Coagulation of cerebral aneurysms;

Carrying out therapeutic electrical stimulation or inhibition of brain structures.

There are the following methods for studying the functions of the central nervous system:

1. Method of cutting the brain stem at various levels. For example, between the medulla oblongata and the spinal cord.

2. Method of extirpation (removal) or destruction of parts of the brain.

3. Method of irritating various parts and centers of the brain.

4. Anatomical and clinical method. Clinical observations of changes in the functions of the central nervous system when any of its parts are affected, followed by a pathological examination.

5. Electrophysiological methods:

A. electroencephalography - registration of brain biopotentials from the surface of the scalp. The technique was developed and introduced into the clinic by G. Berger.

b. registration of biopotentials of various nerve centers; used in conjunction with stereotactic technique, in which electrodes are inserted into a strictly defined nucleus using micromanipulators.

V. evoked potential method, recording the electrical activity of brain areas during electrical stimulation of peripheral receptors or other areas;

6. method of intracerebral administration of substances using microinophoresis;

7. chronoreflexometry - determination of reflex time.

End of work -

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Physiology as a science. Subject, tasks, methods, history of physiology
Physiology (physics - nature) is the science of the normal life processes of the body, its constituent physiological systems, individual organs, tissues, cells and subcellular structures, fur

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And homeokinesis
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And neurohumoral regulation
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And action potentials
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Relationship between action potential and excitability phases
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Ultrastructure of skeletal muscle fiber
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Mechanisms of muscle contraction
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Energy of muscle contraction
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Muscle fatigue
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Motor units
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Smooth muscle physiology
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Postsynaptic potentials
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Properties of nerve centers
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Braking in C.N.S
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Inhibitions in nerve centers
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Reflex coordination mechanisms
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Functions of the spinal cord
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Functions of the medulla oblongata
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Functions of the diencephalon
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Functions of the cerebellum
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Functions of the basal ganglia
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Electroencephalography. Its significance for experimental research and clinical practice
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Blood composition. Basic physiological blood constants
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Composition, properties and significance of plasma components
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Hemoglobin. Its varieties and functions
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Structure and function of platelets
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Fibrinolysis
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Anticoagulant system
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Factors influencing blood clotting
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Blood groups. Rh factor. Blood transfusion
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Protective function of blood. Immunity. Regulation of the immune response
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General plan of the structure of the circulatory system
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In different phases of cardiac activity
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Automaticity of the heart
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Mechanisms of excitability, automation and contractions of cardiomyocytes
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The relationship between excitation, excitability and contraction of the heart. Disorders of the rhythm and functions of the cardiac conduction system
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Mechanisms of regulation of cardiac activity
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Reflex and humoral regulation of heart activity
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Mechanical and acoustic manifestations
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Electrocardiography
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Factors ensuring blood movement
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Blood flow speed
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Blood pressure
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Arterial and venous pulse
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Mechanisms of regulation of vascular tone
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Vasomotor centers
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Reflex regulation of systemic arterial blood flow
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Physiology of the microvasculature
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Regulation of organ circulation
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Mechanisms of external respiration
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Pulmonary ventilation indicators
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Functions of the airways. Protective breathing reflexes. Dead space
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Exchange of gases in the lungs
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Transport of gases by blood
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Exchange of respiratory gases in tissues
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Regulation of breathing. Respiratory center
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Reflex regulation of breathing
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Humoral regulation of respiration
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Breathing at elevated atmospheric pressure. Caisson disease
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Hyperbaric oxygenation
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Composition and physiological significance of saliva
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Mechanisms of saliva formation and regulation of salivation
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Chewing
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Swallowing
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Composition and properties of gastric juice. The meaning of its components
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Regulation of gastric secretion
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The role of the pancreas in digestion
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Mechanisms of production and regulation of pancreatic juice secretion
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Liver functions. The role of the liver in digestion
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The importance of the small intestine. Composition and properties of intestinal juice
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Cavity and parietal digestion
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Functions of the large intestine
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Motor function of the small and large intestines
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Mechanisms of absorption of substances in the digestive canal
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Food motivation
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Nutrients
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Methods for measuring the body's energy balance
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BX
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Physiological basis of nutrition. Power modes
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Exchange of water and minerals
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Regulation of metabolism and energy
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Thermoregulation
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Kidney functions. Mechanisms of urine formation
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Regulation of urine formation
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Non-excretory functions of the kidneys
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Urinary excretion
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Skin functions
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Types V.N.D

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Congenital forms of behavior. Unconditioned reflexes
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Conditioned reflexes, mechanisms of formation, meaning
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Unconditioned and conditioned inhibition
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Dynamic stereotype
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Structure of a behavioral act
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Memory and its importance in the formation of adaptive reactions
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Physiology of emotions
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Stress, its physiological significance
The functional state is the level of activity of the body at which one or another of its activities is performed. The lower levels of F.S. - coma, then sleep. Higher aggressive-defensive

Dream theories
Sleep is a long-term functional state characterized by a significant decrease in neuropsychic and motor activity, which is necessary to restore the brain’s ability to

Theories of sleep mechanisms
1. Chemical theory of sleep. Proposed in the last century. It was believed that during wakefulness, hypnotoxins are formed, which induce sleep. It was subsequently rejected. However, now you are again

Types V.N.D
Based on the study of conditioned reflexes and assessment of the external behavior of animals, I.P. Pavlov identified 4 types of V.N.D. He based his classification on 3 indicators of excitation processes

Functions of the hemispheres
According to I.P. According to Pavlov, the interaction of the organism with the external environment is carried out through stimuli or signals. Depending on the nature of the signals acting on the body, he identified two signals:

Thinking and consciousness
Thinking is a process of human cognitive activity, manifested by a generalized reflection of the phenomena of the external world and one’s internal experiences. The essence of thinking is the ability to mentally

Unconditioned reflex, conditioned reflex, humoral mechanisms of regulation of sexual functions
Sexual behavior plays a special role in various forms of behavior. It is necessary for the conservation and distribution of the species. Sexual behavior is completely described by P.K. Anokhina.

Adaptation, its types and periods
Adaptation is the adaptation of the structure, functions of organs and the body as a whole, as well as the population of living beings, to environmental changes. There are genotypic and phenotypic adaptation. Basically

Physiological basis of labor activity
Labor physiology is an applied branch of human physiology and studies the physiological phenomena that accompany various types of physical and mental labor. Mental

Biorhythms
Biorhythms are called cyclic changes in the functions of organs, systems and the body as a whole. The main characteristic of cyclic activity is its periodicity, i.e. time for koto

Periods of human ontogenesis
The following periods of human ontogenesis are distinguished: Antenatal ontogenesis: 1. Germinal or embryonic period. The first week after conception. 2.Embryonic

Development of the neuromuscular system of children
Newborns anatomically have all skeletal muscles. The number of muscle fibers does not increase with age. The growth of muscle mass occurs due to an increase in the size of myofibrils. They

Indicators of strength, work and endurance of muscles during development
With age, the strength of muscle contractions increases. This is explained not only by an increase in the length and diameter of myocytes, an increase in total muscle mass, but also by an improvement in motor reflexes. Nap

Physicochemical properties of children's blood
The relative amount of blood decreases as we grow older. In newborns it makes up 15% of body weight. For 11 year olds it is 11%, for 14 year olds it is 9%, and for adults it is 7%. Specific gravity of blood in newborns

Changes in the cellular composition of blood during postnatal ontogenesis
In newborns, the number of red blood cells is relatively higher than in adults and ranges from 5.9-6.1 * 1012/l. By the 12th day after birth it averages 5.4 * 1012/l, and by

Features of cardiac activity in children
In newborns, the cardiovascular system adapts to existence in the extrauterine period. The heart is round in shape and the atria are relatively larger than the ventricles of an adult

Functional properties of the vascular system in children
The development of blood vessels as they grow older is accompanied by an increase in their length and diameter. At an early age, the diameter of the veins and arteries is approximately the same. But the older the child, the more the diameter increases

Cardiac activity and vascular tone
In newborns, heterometric myogenic regulatory mechanisms are weakly manifested. Homeometric ones are well expressed. At birth there is normal innervation of the heart When the parasympathetic system is excited

Age-related features of external respiration functions
The structure of the respiratory tract of children differs markedly from the respiratory system of an adult. In the first days of postnatal ontogenesis, nasal breathing is difficult, since the child is born with insufficient development

Gas exchange in the lungs and tissues, gas transport in the blood
In the first days after birth, ventilation increases and the diffusion surface of the lungs increases. Due to the high rate of alveolar ventilation, there is more oxygen in the alveolar air of newborns (

Features of breathing regulation
The functions of the bulbar respiratory center are formed during intrauterine development. Premature babies born at 6-7 months are capable of independent breathing. Respiratory periodic movements

General patterns of nutritional development in ontogenesis
During ontogenesis, a gradual change in nutritional types occurs. The first stage is histotrophic nutrition from the reserves of the egg, yolk sac and uterine mucosa. Since the formation of the parade ground

Features of the functions of the digestive organs in infancy
After birth, the first digestive reflex is activated - sucking. It is formed very early in ontogenesis at 21-24 weeks of intrauterine development. Sucking begins as a result of irritation of the mechanical

Functions of the digestive organs in definitive nutrition
With the transition to definitive nutrition, the secretory and motor activity of the child’s digestive canal gradually approaches those of adulthood. Using predominantly dense

Metabolism and energy in childhood
The intake of nutrients into the child’s body on the first day does not cover its energy costs. Therefore, glycogen reserves in the liver and muscles are used. Its quantity in them is rapidly decreasing.

Development of thermoregulation mechanisms
In a newborn baby, the rectal temperature is higher than that of the mother and is 37.7-38.20 C. After 2-4 hours it decreases to 350 C. If the decrease is greater, this is one of the

Age-related features of kidney function
Morphologically, bud maturation ends by 5-7 years. Kidney growth continues up to 16 years. The kidneys of children under 6-7 months are in many ways reminiscent of an embryonic kidney. In this case, the weight of the kidneys (1:100) relates

Child's brain
In postnatal ontogenesis, the improvement of unconditional reflex functions occurs. Compared with an adult, newborns have much more pronounced processes of irradiation of excitation

Higher nervous activity of a child
A child is born with a relatively small number of inherited unconditioned reflexes, mainly of a protective and nutritional nature. However, after birth he finds himself in a new environment and these reflexes