Functions of the red core and black matter. Midbrain: structure, function and development

3.3.4 Red core

Among the nuclei of the gray matter of the midbrain, the most significant is the red nucleus, (nucleus ruber). This elongated formation extends in the tectum of the cerebral peduncle from the hypothalamus of the diencephalon to the lower colliculus, where an important descending tract, tractus rubrospinalis, begins from it, connecting the red nucleus with the anterior horns of the spinal cord. This bundle, after exiting the red nucleus, intersects with a similar bundle of the opposite side in the ventral part of the median suture, forming the ventral intersection of the tepal.

3.3.5 Gray and white matter of the cerebral aqueduct

The aqueduct of the midbrain, or the sylvian aqueduct (aqueductus mesencephali) is a narrow channel 1.5-2.0 cm long, connecting the cavities of the III and IV ventricles. It is surrounded by the central gray matter (substantia grisea centralis), which is part of the reticular formation of the midbrain. It consists of small cells that form a layer 2-5mm thick. It contains the nuclei of the oculomotor, trochlear and trigeminal nerves, as well as the accessory nucleus of the oculomotor nerve (parasympathetic nucleus of the autonomic nervous system) and the intermediate nucleus (one of the nuclei of the reticular formation).

3.4 White and gray matter of the diencephalon

The diencephalon (diencephalon), lies under the corpus callosum and fornix, fused on the sides with the cerebral hemispheres. The dorsal section is represented by a pair of optic hillocks (thalamus opticus). The thalamus also includes structures that are combined in a foreign land (metathalamus) - a pillow (pulvinar), medial and lateral geniculate bodies (corpus geniculatum lateralis et medialis).

In the picture: 1 - corpus callosum, 2 - cavum septi pellucidi, 3 - septum pellucidum, 4 - fornix (cross section of the pillars), 5 - comissura anterior, 6 - adheiso interthalamica, 7 - comissura posterior, 8 - tectum mesencephali, 9 - corpus pineale, 10 - thalamus, 11 - ventriculus tertius, 12 - nucl. caudatus.

At the top of the visual hillocks is the epithalamus. In the ventral part of the diencephalon is the lower tuberous region (hypothalamus).

The hypothalamus is isolated in the diencephalon as a separate area, and the thalamus, epithalamus and metathalamus are combined into the visual brain (thalamencephalon).

The cavity of the diencephalon is the third ventricle (ventriculus tertius).

The gray matter of the diencephalon is composed of nuclei belonging to the subcortical centers of all types of sensitivity. In the diencephalon, the reticular formation, centers of the extrapyramidal system, autonomic centers (regulate all types of metabolism), neurosecretory nuclei are located.

The white matter of the diencephalon is represented by the pathways of the ascending and descending directions, providing a two-way connection of the subcortical formations with the cerebral cortex and the nuclei of the spinal cord. In addition, the diencephalon includes two endocrine glands - the pituitary gland, which, together with the corresponding nuclei of the hypothalamus, participates in the formation of the hypothalamic-pituitary system, and the pineal gland (pineal gland).

3.4.1 Thalamus

The optic tubercle (thalamus) is a large pair of ovoid gray matter accumulations, with the pointed end forming the anterior tubercle of the thalamus (tuberculum anterius thalami), and the thickened edge is called the pillow (pulvinar). These accumulations are located in the lateral walls of the diencephalon on the sides of the third ventricle. Their medial surface, covered with a thin layer of gray matter, freely protrudes into the cavity of the third ventricle, being its lateral wall; on this surface there is a sub-hillock groove (sulcus hypothalamicus), delimiting the thalamus from the hypothalamus. The dorsal surface is covered with a thin layer of white matter - stratum zonale. The gray matter, which is part of the (visual) tubercle, forms the nuclei of the visual tubercle, nuclei thalami. Currently, about 40 nuclei are isolated. The main nuclei of the thalamus are: 1. The anterior nucleus (nucleus anterior thalami), which is located in the anterior tubercle of the thalamus; 2. The medial nucleus (nucleus medialis thalami) lies at the medial surface of the visual hillock; 3. Lateral nucleus (nucleus lateralis thalami), the largest of the three nuclei, is located ventro-lateral in relation to the anterior and medial.

These nuclei are delimited from one another and themselves are divided into a number of smaller nuclei by means of white layers, the medullary plates of the optic tubercle (laminae medullares thalami). Among these plates, an external and internal are distinguished, as well as the so-called ethmoid layer, which delimits, together with the external cerebral plate, the optic tubercle from its lateral side. At the border of the transition of the upper surface to the dorsal is a narrow cerebral strip of the optic tubercle (stria medullaris thalami), then forming a leash triangle (trigonum habenulae), and then a leash (habenula).

The processes of the nerve cells of the second (conductor) neurons of all sensitive pathways (with the exception of the olfactory, gustatory and auditory) come into contact with the nerve cells of the thalamus. Therefore, the thalamus is actually a subcortical sensory center. Part of the processes of neurons of the thalamus is directed to the nuclei of the striatum of the terminal brain (in this regard, the thalamus is considered as a sensitive center of the extrapyramidal system), and part - thalamocortical bundles (fasciculi thalamocorticales) - to the cerebral cortex. Under the thalamus is the so-called subthalamic region (regio subthalamica), which continues downward into the lining of the brain stem.

Nerve impulses, giving them an emotional coloring. The specific part of the nervous system is divided into central and peripheral (according to the topographic principle). The central one includes the brain and spinal cord, the peripheral one - nerves, plexuses, nodes (ganglia), peripheral nerve endings. On a functional basis, the central nervous system is divided into animal (somatic, animal ...

Densities on the background intravenous administration KB 05-1. From the very beginning of its clinical use, MRI has become the method of choice for imaging foci of spinal demyelination. As in the study of the cerebral form of multiple sclerosis, T2-weighted MRI are the most informative for identifying foci of demyelination in the spinal cord. T1-weighted tomograms are useful in ...

The human brain is a complex structure, an organ of the human body that controls all processes in the body. The midbrain is included in its middle section, belongs to the most ancient visual center, in the process of evolution it acquired new functions, took a significant place in the life of the human body.

The midbrain is a small (only 2 cm) section of the brain, one of the elements of the brain stem. Located between the subcortex and the posterior region of the brain, it is located in the very center of the organ. It is a connecting segment between the upper and lower structures, since the nerve tracts of the brain pass through it. Anatomically, it is not as complicated as the rest of the sections, but in order to understand the structure and functions of the midbrain, it is better to consider it in cross section. Then 3 parts of it will be clearly visible.

Roof

In the posterior (dorsal) section, there is a plate of a quadruple, consisting of two pairs of hemispherical hillocks. It is a roof, placed above the water supply, and covers its cerebral hemispheres. Above is a pair of visual mounds. They are larger in size than the lower elevations. Those mounds that lie below are called auditory. The system communicates with the geniculate bodies (elements of the diencephalon), the upper ones - with the lateral ones, the lower ones - with the medial ones.

Tire

The site follows the roof, includes the ascending paths of nerve fibers, reticular formation, nuclei cranial nerves, medial and lateral (auditory) loops and specific formations.

Brain legs

In the ventral region, the legs of the brain lie, represented by a pair of ridges. Most of them include the structure of nerve fibers belonging to the pyramidal system, which diverges to the cerebral hemispheres. The legs cross the longitudinal medial bundles, they include the roots of the oculomotor nerve. In the depths, there is a perforated substance. At the base there is a white matter, downward pathways stretch along it. In the space between the legs, there is a fossa where the blood vessels pass.

The midbrain is a continuation of the bridge, the fibers of which stretch transversely. This makes it possible to clearly see the boundaries of the departments on the basal (main) surface of the brain. From the dorsal region, the restriction occurs from the auditory hills and the transition of the fourth ventricle to the aqueduct.

Midbrain nuclei

In the midbrain, the gray matter is located in the form of a concentration of nerve cells, forming the nuclei of the nerves of the skull:

1. The nuclei of the oculomotor nerve are located in the operculum, closer to the middle, ventral to the aqueduct. They form a layered structure, participate in the occurrence of reflexes and visual reactions in response to signals. Also, during the formation of visual stimuli, the nuclei control the movement of the eyes, body, head and facial expressions. The system complex includes the main nucleus, consisting of large cells, and small-cell nuclei (central and outer).
2. The core of the trochlear nerve is paired elements, located in the segment of the tire in the region of the lower hillocks directly under the water supply. It is represented by a homogeneous mass of large isodiametric cells. Neurons are responsible for hearing and complex reflexes, with their help a person reacts to sound stimuli.
3. The reticular formation is represented by an accumulation of reticular nuclei and a network of neurons, located in the thickness of the gray matter. In addition to the middle center, it captures the diencephalon and medulla oblongata, education is associated with all parts of the central nervous system. It affects motor activity, endocrine processes, affects behavior, attention, memory, inhibition.

Specific formations

The structure of the midbrain includes important structural formations. The centers of the extrapyramidal system of the subcortex (a set of structures responsible for movement, body position and muscle activity) include:

Red kernels

Red nuclei are located in the tectum, ventral to the gray matter and dorsal to the substantia nigra. Their color is provided by iron, which acts as ferritin and hemoglobin. The cone-shaped elements extend from the level of the lower hillocks to the hypothalamus. They are connected by nerve fibers with the cerebral cortex, cerebellum, and nuclei of the subcortex. Having received information from these structures about the position of the body, the cone-shaped elements send a signal to the spinal cord and correct muscle tone, prepare the body for the upcoming movement.

If the connection with the reticular formation is broken, decerebration rigidity develops. It is characterized by strong tension in the extensor muscles of the back, neck and limbs.

Black matter

If we consider the anatomy of the midbrain in section, from the bridge to the diencephalon in the pedicle, two continuous stripes of the substantia nigra are clearly visible. These are clusters of neurons abundantly supplied with blood. The dark color is provided by the pigment melanin. The degree of pigmentation is directly related to the development of structural functions. It appears in humans by 6 months of life, reaching maximum concentration by 16 years. The substantia nigra divides the leg into sections:

• dorsal is a tire;
• the ventral section is the base of the leg.

The substance is divided into 2 parts, one of which - pars compacta - receives signals in the chain of the basal ganglia, delivering the hormone dopamine to the telencephalon to the striatum. The second, pars reticulata, transmits signals to other parts of the brain. The nigrostriatal tract originates in the substantia nigra, which belongs to one of the main nerve pathways of the brain that initiate motor activity. This section mainly carries out conductive functions.

In case of damage to the substantia nigra, a person experiences involuntary movements of the limbs and head, difficulty in walking. With the death of dopamine neurons, the activity of this pathway decreases, and Parkinson's disease develops. It is believed that with an increase in dopamine production, schizophrenia develops.

The midbrain cavity is the Salvian aqueduct, which is about one and a half centimeters long. A narrow canal runs ventral from the quadruple, surrounded by gray matter. This remainder of the primary brain bladder connects the cavities of the third and fourth ventricles. It contains cerebrospinal fluid.

Functions

All parts of the brain work interconnected, together creating a unique system for ensuring human life. The main functions of the midbrain are designed to fulfill the following role:

• Sensory functions. The load for sensory sensations is borne by the neurons of the nuclei of the quadruple. Signals from the organs of sight and hearing, the cerebral cortex, the thalamus and from other brain structures come to them along the pathways. They provide accommodation of vision to the degree of illumination by changing the size of the pupil; his movement and turns of the head towards the annoying factor.
• Conductor. The midbrain plays the role of a conductor. Basically, the base of the legs, nuclei and black matter are responsible for this function. Their nerve fibers are connected to the cortex and the underlying brain regions.
• Integrative and motor. Receiving commands from sensory systems, the nuclei convert signals into active action... Motor commands are given by the stem generator. They enter the spinal cord, which allows not only muscle contraction, but also the formation of body posture. A person is able to maintain balance in various positions. Reflex movements are also performed when the body moves in space, helping to adapt so as not to lose the bearings.

The midbrain contains a center that regulates pain. Receiving a signal from the cerebral cortex and nerve fibers, the gray matter begins to produce endogenous opiates, which determine the pain threshold, raising or lowering it.

Reflex functions

The midbrain performs its functions through reflexes. With the help of the medulla oblongata, complex movements of the eyes, head, trunk, fingers are performed. Reflexes are subdivided into:

• visual;
• auditory;
• watchdogs (indicative, answering the question "what is it?").

They also provide a redistribution of skeletal muscle tone. The following types of reactions are distinguished:

• Static ones include two groups - postural reflexes, which are responsible for maintaining a person's posture, and straightening ones, which help to return to a normal position if it has been violated. This type of reflexes regulates the medulla oblongata and spinal cord, reading data from the vestibular apparatus, with tension of the cervical muscles, visual organs, skin receptors.
• Statokinetic. Their goal is to maintain balance and orientation in space while moving. A striking example: a cat falling from a height will land on its paws anyway.

The statokinetic group of reflexes is also divided into types.

• With linear acceleration, the lift reflex appears. When a person quickly rises up, the flexor muscles tighten, with a decrease, the tone of the extensor muscles increases.
• During angular acceleration, for example, during rotation to maintain visual orientation, nystagmus of the eyes and head occurs: they are turned in the opposite direction.

All midbrain reflexes are classified as congenital, that is, unconditioned types. An important role in the integration processes is assigned to the red core. Its nerve cells activate the muscles of the skeleton, help to maintain the usual position of the body and take a posture to perform any manipulations.

The substantia nigra is a participant in the management of muscle tone and restoration of normal posture. The structure is responsible for the sequence of acts of chewing and swallowing, the work of fine motor skills of the hands and eye movements depend on it. The substance is a figurant in the work of the autonomic system: it regulates the tone of blood vessels, heart rate, respiration.

Age features and prevention

The brain is a complex structure. It functions with the close interaction of all segments. The center that controls the middle section is the cerebral cortex. With age, connections become weaker, the activity of reflexes weakens. Since the site is responsible for motor function, even minor disruptions in this tiny segment lead to the loss of this important ability. It is more difficult for a person to move, and serious disorders lead to diseases of the nervous system and complete paralysis. How to prevent disturbances in the work of the brain department in order to stay healthy until a ripe old age?

First of all, head bangs should be avoided. If this happens, it is necessary to begin treatment immediately after the injury. It is possible to preserve the functions of the midbrain and the entire organ until old age, if you train it with regular exercises:

1. For physical and mental health, it is important what lifestyle a person leads. Drinking alcohol and smoking destroy neurons, which gradually leads to a decrease in mental and reflex activity. Therefore from bad habits should be abandoned, and the earlier the better.
2. Moderate physical activity, walks in nature supply the brain with oxygen, which has a beneficial effect on its activity.
3. Do not give up reading, solving charades and puzzles: intellectual activity keeps the brain active.
4. An important aspect of the functioning of brain structures is nutrition: fiber, protein, greens must be present in the diet. The midbrain responds positively to intake of antioxidants and vitamin C.
5. Need to control blood pressure: vascular health affects general state person.

The brain is a flexible system that can be successfully developed. Therefore, constantly improving your mind and body, you can maintain clarity of thoughts and physical activity until a ripe old age.

The midbrain, its structure and functions are determined by the location of the structure, provide movement, auditory and visual reactions. If there are difficulties with maintaining balance, lethargy, you should consult a doctor and undergo an examination to find the cause of the disorders and eliminate the problem.

RED CORE RED CORE

(nucleus ruber), the structure of the midbrain of terrestrial vertebrates, located symmetrically in the thickness of the legs of the brain under the central gray matter. K. i. consists of a phylogenetically ancient (reptiles, birds) large-cell part (diameter of the neuron body 50-90 microns), from which the descending rubrospinal path begins, and a young (mammals) small-cell part (dia. 20-40 microns), switching impulses from the nuclei the cerebellum to the thalamus. The number of small cell neurons increases in primates and humans. K. i. has projections to the motor nuclei of the spinal cord, which control the movement of the fore and hind limbs, and is under the control of the cerebral cortex. To. I. - an important intermediate instance of the integration of the influences of the forebrain and cerebellum in the formation of dvpgat. commands to the neurons of the spinal cord.

.(Source: "Biological Encyclopedic Dictionary." Ed. M. S. Gilyarov; Editorial board: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin et al. - 2nd ed., Revised - M .: Sov.Encyclopedia, 1986.)

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- (n. ruber, PNA, BNA, jna) large I. reddish yellow in color, located in the anterior part of the lining of the midbrain; refers to the extrapyramidal system ... Large Medical Dictionary

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Spinal cord functions. The spinal cord performs two functions - reflex and conductive. The spinal cord reflexes can be divided into motor (carried out by alpha motoneurons of the anterior horns), and vegetative (carried out by the cells of the lateral horns). Motor reflexes - flexion and extensor, tendon, myotatic, rhythmic, tonic. The centers of the autonomic nervous system are located in the spinal cord: vasomotor, sweating, respiratory, urinary, defecation, genital.

The conductive function of the spinal cord is associated with the transmission of information flow from the periphery to the overlying parts of the nervous system and with the conduction of impulses from the brain to the spinal cord.

Brain functions. There are five main divisions in the brain: the medulla oblongata, posterior, middle, diencephalon and anterior (terminal) brain.

Functions of the medulla oblongata. Performs two functions - reflex and conductive. Through the medulla oblongata, the following reflexes are carried out: 1) protective: coughing, sneezing, blinking, vomiting, tearing; 2) food: sucking, swallowing, secretion of the digestive glands; 3) cardiovascular, regulating the activity of the heart and blood vessels; 4) in the medulla oblongata is the respiratory center, which provides ventilation of the lungs; 5) posture change is carried out due to static and statokinetic reflexes.

Through the medulla oblongata, there are pathways connecting the cortex, intermediate, middle, cerebellum and spinal cord with a two-way connection.

Hindbrain functions. The hindbrain includes the pons and cerebellum. bridge are determined by the structures included in it. Ascending and descending paths pass through the bridge connecting the medulla oblongata and cerebellum with the cerebral hemispheres. It conducts impulses from one hemisphere of the cerebellum to the other, coordinating muscle movements on both sides of the body; participates in the regulation of complex motor acts, muscle tone and body balance.

Cerebellumis a suprasegmental department of the central nervous system that does not have direct communication with the executive bodies. He takes part in the regulation of postural-tonic reactions and coordination of motor activity. After removal of the cerebellum in the animal, disorders of motor acts occur: reflexes of body position, static reflexes and voluntary movements are disturbed. With unilateral removal of the cerebellum, a violation of movements occurs on the side of the operation: the muscle tone increases, the head and trunk turn in the same direction, and therefore the animal makes movements in a circle. The cerebellum takes part in the regulation of autonomic functions: respiration, digestion, cardiovascular activity, thermoregulation.

Midbrain functions. The midbrain includes the legs of the brain and the quadruple. The main centers of the midbrain: the red nucleus and the substantia nigra. Red core midbrain performs motor functions - regulates skeletal muscle tone. If a cat is made a cross-section between the medulla oblongata and the midbrain, then the muscle tone, especially the extensors, sharply increases. An animal placed on legs extended like sticks can stand. This condition is called decerebral rigidity.

Black substancemidbrain activates the forebrain, imparting emotional coloring to some behavioral reactions. The function of the substantia nigra is associated with the implementation of the reflexes of chewing and swallowing.

Cores of the upper mounds are the primary visual centers. They turn the eyes and head towards the stimulus (visual orientation reflex). Cores of the lower mounds are primary hearing centers... They regulate the orienting reflexes that arise in response to sound stimuli.

The functions of the diencephalon. The diencephalon consists of the thalamus, hypothalamus, epithalamus, and metathalamus. Thalamus is a collector of almost all types of sensitivity (except olfactory). According to the functional significance, the thalamic nuclei are divided into specific, non-specific and associative.

Specific nuclei of the thalamus thalamus regulate tactile, temperature, pain and gustatory sensitivity, as well as auditory and visual sensations. Nonspecific nuclei of the thalamus have both activating and inhibitory effects on small areas of the cortex. Associative nuclei of the thalamus transmit impulses from switching nuclei to the associative zones of the cortex.

Hypothalamus is the highest subcortical center of the autonomic nervous system. Functionally, the nuclei of the hypothalamus are divided into the anterior, middle and posterior groups of nuclei. Front nucleithe hypothalamus are centers of parasympathetic regulation; they also produce releasing factors that regulate the activity of the pituitary gland. Rear nuclei regulate sympathetic influences. Stimulation of nuclei middle group leads to a decrease in the influences of the sympathetic nervous system.

Epithalamus (pineal gland)regulates the processes of sleep and wakefulness. Metathalamus (geniculate bodies)participate in the regulation of vision and hearing.

Limbic system. The limbic system includes the cingulate gyrus, the hippocampus, part of the nuclei of the thalamus and hypothalamus, the septum, etc. This system is involved in the regulation of autonomic functions, influences the change of sleep and wakefulness, provides memory processes and plays an important role in the formation of emotions.

Reticular formation. This is a special system of nerve cells with densely intertwined processes. It is located throughout the medulla oblongata, posterior, midbrain and diencephalon and has an activating and inhibitory effect on neurons in different parts of the central nervous system.

Basal ganglia (nuclei). The basal nuclei include the striatum, consisting of the caudate and lenticular nuclei and orgada. These nuclei coordinate movements, participate in the formation of conditioned reflexes and the implementation of complex unconditioned reflexes (defensive, food-processing, etc.).

Functions of the cerebral cortex.The cerebral hemispheres consist of white matter, covered with gray outside (bark), the thickness of which in various parts of the cerebral hemispheres is 1.3-5 mm. The number of neurons in the cortex reaches 10-14 mln. In the cerebral cortex, the bodies of neurons form six layers: 1st molecular; 2nd outer granular; 3rd outer pyramidal; 4th inner granular; 5th inner pyramidal; 6th multimorphic. Areas of the cortex that are similar in structure, topography, and in terms of differentiation in ontogenesis are called cytoarchitectonic fields. K. Brodman identified 52 cytoarchitectonic (cellular) fields in the cortex.

Localization of functions in the cortex. In the cerebral cortex, the following zones are distinguished: sensitive (sensory), motor (motor) and associative

Sensory areas of the cortex. Afferent impulses from all receptors (with the exception of the olfactory receptors) enter the cortex through the thalamus. The central projections of somatic and visceral sensation are separated into primary and secondary somatosensory zones. Primary somatosensory zonelocated in the postcentral gyrus (fields 1,2,3). It receives impulses from receptors of the skin and the locomotor apparatus ... Secondary somatosensory zone located ventrally in the area of \u200b\u200bthe lateral (Sylvian) groove. There is a projection of the body surface, but less clear than in the primary somatosensory area.

Visual area of \u200b\u200bthe cortexlocated in the occipital region of the cortex on both sides of the groove (fields 17,18,19). Auditory cortex located in the temporal region (fields 41,42). Olfactory cortex located at the base of the brain, in the area of \u200b\u200bthe parahippocampal gyrus (field 11). Flavor analyzer projection localized in the lower part of the postcentral gyrus (field 43). Speech zones of the cortex. With the function of speech in the cerebral cortex, fields 44 and 45 (Broca's center) and field 22 (Wernicke's center), located in the left cerebral hemisphere of right-handed people, are associated.

Motor cortex zoneslocalized in the precentral gyrus (fields 4, 6). Electrical irritation of the upper gyrus causes movement of the muscles of the legs and trunk, the middle - the arms, the lower - the muscles of the face. The zone that controls the movements of the hand, tongue, and facial muscles is especially large.

Associative zones of the cortexoccupy 1/3 of its entire area and carry out communication between different areas of the cortex, integrating all impulses entering the cortex into integral acts of learning (reading, speech, writing), logical thinking, memory and, finally, a conscious reflection of reality.

Bioelectrical activity of the cortex. Oscillations of electrical potentials of the cortex were first recorded by V.V. Pravdich-Neminsky in 1913. The curve reflecting the electrical activity of cortical neurons is called an electroencephalogram (EEG). For EEG registration, multichannel electroencephalographs are used, and the international scheme “10-20” is used for the location of the electrodes.

There are the following EEG rhythms: alpha rhythm with a frequency of 8-13 Hz and an amplitude of 50 µV; beta rhythm with a frequency of 14-30 Hz and an amplitude of 25 μV; theta rhythm with a frequency of 4-8 Hz and an amplitude of 100-150 μV; delta rhythm with a frequency of 0.5-4 Hz and an amplitude of 250-300 μV.

In clinical practice, EEG allows you to assess functional state brain.

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The structure of the midbrain includes the quadruple and the legs of the brain (Fig. 28). The main centers of the midbrain: red nucleus, substantia nigra, nuclei of the oculomotor and block nerves.

The midbrain is a subcortical regulator of muscle tone, the center of visual and auditory orienting reflexes, as well as some complex motor reflex acts (swallowing and chewing).

The influence of the midbrain on the tone of the skeletal muscles is carried out through the red nucleus. Impulses from the cerebral cortex, subcortical nuclei and cerebellum, as well as from the reticular formation of the brain stem, converge to it. Turning off the red nucleus leads to a sharp increase in skeletal muscle tone (decerebral rigidity).

The substantia nigra of the midbrain activates the forebrain, giving emotional coloring to some behavioral reactions. Dopamine plays an important role in the transmission of these influences. The function of the substantia nigra is associated with the implementation of the reflexes of chewing and swallowing.

With the joint participation of the middle and medulla oblongata, congenital tonic reflexes are realized: postures (body positions), rectifying, lift reflexes and reflex movements eyeballs when the body rotates (nystagmus). The midbrain regulates motor orientation reflexes. The anterior hillocks of the quadruple are the primary visual centers: they rotate the eyes and head towards the stimulus (visual orientation reflex).

Fig. 28. The anterior surface of the brain stem, the lower surface of the cerebellum:

1 - optic nerve; 2 - an island; 3 - pituitary gland; 4 - cross optic nerves; 5 - funnel; 6 - gray bump; 7 - mastoid; 8 - a fossa between the legs of the brain; 9 - the legs of the brain; 10 - lunar node; 11 - a small root of the trigeminal nerve; 12 - a large root of the trigeminal nerve; 13 - abducent nerve; 14 - glossopharyngeal nerve; 15 - choroid plexus of the IV ventricle; sixteen - nervus vagus; 17 - accessory nerve; 18 - the first cervical nerve; 19 - the cross of the pyramids; 20 - pyramid; 21 - hypoglossal nerve; 22 - auditory nerve; 23 - intermediate nerve; 24 - facial nerve; 25 - trigeminal nerve; 26 - varoliev bridge; 27 - block nerve; 28 - external geniculate body; 29 - the oculomotor nerve; 30 - visual path; 31-32 - anterior perforated substance; 33 - outer olfactory strip; 34 - olfactory triangle; 35 - olfactory tract; 36 - olfactory bulb

The posterior hillocks of the quadruple are reflex centers of the orienting auditory reflexes. When the auditory receptors are irritated, alertness and head turn towards the sound source occur.

Midbrain functions in brief

In the human brain, almost every part of it is irreplaceable. Together, these parts create one incredibly fine-tuned system. It is hardly worth expecting that any technique will be able to at least replicate the functions of the brain in the near future. Unfortunately, only a very small percentage of the human brain has been studied today. However, quite a lot is known about the functions of the brain and parts of it like the midbrain.
In short, the functions of the midbrain can be reduced to the following types: sensory, movement, conduction, reflexes.
The midbrain is necessary for a person for the normal functioning of certain reflexes, for example, rectifying and setting. Thanks to such reflexes, a person can stand and walk. In addition, the midbrain coordinates and regulates muscle tone.

The structure and function of the midbrain

Therefore, the normal functioning of the midbrain is a prerequisite for the correct coordination of movements. The next important function of the midbrain is associated with vegetative processes. These processes include: chewing, swallowing, breathing, blood pressure.

Based on the foregoing, it can be seen that, in general, the midbrain is responsible for the body's response to various stimuli. Further, in addition to the reflexes already mentioned, the midbrain also ensures the restoration of balance, posture, when its normal position has been disturbed.
Thus, it can be seen that the midbrain is responsible for a number of functions and reflexes in the human body: movements as a reaction to stimuli, binocular vision, pupil response to light (accommodation), simultaneous rotation of the eyes and head, processing of primary information from the sense organs , muscle tone.
All this means that the importance of the midbrain is difficult to overestimate.

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Gray matter of the telencephalon.

The gray matter of the telencephalon is represented by two formations: the basal (subcortical) nuclei, which are earlier structures, and the cerebral cortex, which is a later and perfect structure of the brain.

Basal nuclei lie in the form of separate formations in the thickness of the white matter, closer to the base of the brain (Fig. 27). In connection with their position, they got their name basal (subcortical, central) nuclei, nuclei basales. There are four nuclei in each hemisphere: caudate, lenticular, hedge, and amygdala.

Most medially and anterior to the thalamus, the caudate nucleus, nucleus caudatus, is localized. He distinguishes an expanded anterior part - the head, caput nuclei caudati, which is located in the frontal lobe and below adjoins the anterior perforated substance, in contact with the lenticular nucleus. Posteriorly, the head narrows and passes into the body, corpus nuclei caudati, which is located in the parietal lobe and adjacent to the thalamus, separated from it by a terminal strip. The body passes into the thinnest part - the tail, cauda nuclei caudati, which passes into the temporal lobe and reaches the amygdala.

The lenticular nucleus, nucleus lentiformis, is located lateral to the caudate nucleus and thalamus. It has the shape of a triangle, with its base facing laterally. Thin layers of white matter located sagittally divide it into three parts. Lateral part called a shell, putamen, dark in color. The other two parts are lighter in color, located medially and are called the medial and lateral cerebral plates, laminae medullares medialis et lateralis, which are combined under the general name of the pallidus globus pallidus. The plates have another name - medial and lateral pale balls, globus pallidus medialis et lateralis.

The caudate and lenticular nuclei are combined under the general name of the striatum, corpus striatum. The caudate nucleus and shell are newer formations - neostriatum (striatum), and the pallidus is an older formation - paleostriatum (pallidum). These names formed the basis of the term striopallidal system.

The fence, claustrum, is located lateral to the shell. This nucleus looks like a thin plate and is separated from the shell by an interlayer of white matter - the outer capsule, capsula externa.

The amygdala, corpus amygdaloideum, is located in the temporal lobe 1.5–2 cm posterior to its pole.

All basal nuclei belong to the subcortical motor centers. They have a wide connection with the thalamus and hypothalamus, with the substantia nigra and with the red nucleus, and through them - with the cerebral cortex and motor neurons of the anterior columns of the spinal cord.

Their function is to maintain the tone of the skeletal muscles, the implementation of this musculature of involuntary movements and automatism of a number of functions based on voluntary movements, but switched to an automatic mode of execution, for example, walking, speaking, stereotyped movements.

The cerebral cortex (cloak), cortex cerebri (pallium), represented by a layer of gray matter 1.5–5 mm thick, located outside over the entire surface of the cerebral hemispheres.

The bark is made up of six layers of nerve cells. The distribution of these cells is denoted by the term "cytoarchitectonics". The largest cells (the layer of large pyramidal cells, or Betz cells) are concentrated in the fifth layer - the inner pyramidal plate. Many nerve fibers are located between the cells. The peculiarity of their distribution in the cortex is defined by the term "myeloarchitectonics".

Based on the structural features of individual parts of the cortex, cytoarchitectonic maps were created, in which, according to different authors, from 52 to 150 fields and more are distinguished. Within these fields there are centers that regulate certain functions in the human body.

Midbrain functions

Localization of the cortical nuclei of the analyzers on the upper-lateral surface of the left hemisphere of the brain: 1 - the core of the skin analyzer; 2 - the core of stereognosy; 3 - the core of the motor analyzer; 4 - the core of praxia; 5 - the core of the combined rotation of the head and eyes; 6 - the core of the auditory analyzer; 7 - the core of the vestibular analyzer; A - the core of the motor analyzer of oral speech; B - the core of the auditory analyzer of oral speech; B - the core of the motor analyzer of written speech; G - the core of the visual analyzer of written speech

Figure: 29. Localization of the cortical nuclei of the analyzers on the medial and lower surfaces of the right hemisphere of the brain: 1 - the nucleus of the analyzers of smell and taste; 2 - the core of the motor analyzer; 3 - the core of the vision analyzer

Localization of functions in the cortex of the cerebral hemispheres. IP Pavlov considered the cerebral cortex as a huge receiving surface (450,000 mm 2), as a set of cortical ends of the analyzers. The analyzer consists of three parts: 1) peripheral or receptor, 2) conductive and 3) central or cortical. The cortex (end of the analyzer) has a core and a periphery. The nucleus contains the same neurons belonging to only one specific analyzer. Its location is clearly defined. It is the highest analysis and synthesis of information coming from receptors.

The periphery of the cortical end of the analyzer has no clear boundaries, the density of cells is reduced in comparison with the nucleus. The analyzer peripheries overlap each other and are represented by neurons in the cortical representations of adjacent nuclei. A simple, elementary analysis and synthesis of information takes place in them.

Ultimately, in the cortical end of the analyzer, based on the analysis and synthesis of the incoming information, responses are generated that regulate all types of human activity. In the clinical aspect, the cortical ends of the analyzers (their nuclei) are considered in relation to the shares of the cerebral hemispheres, their convolutions and grooves. The cortical ends of almost all analyzers are located symmetrically in both hemispheres.

1. The cortical nucleus of general sensitivity, or skin analyzer (tactile, pain, temperature sensitivity), is located in the postcentral gyrus (Fig. 28). The skin surface of the human body in this gyrus is projected upside down and in area is directly proportional to the functional significance of this or that skin area of \u200b\u200bthe body (Fig. 30, A). Therefore, most of the gyrus cortex is associated with receptors in the upper limb (especially the skin of the thumb) and scalp (especially the skin of the lip area).

The cortical nucleus of the sense of stereognosy (recognition of objects by touch) is located in the upper parietal lobule of the hemispheres.

3. The cortical nucleus of the motor analyzer, that is, the nucleus of proprioceptive stimuli emanating from the structures of the musculoskeletal system, is localized in the precentral gyrus and the pericentral lobule. Receptor fields, as in the case of a skin analyzer, are projected upside down in direct proportion to the functional significance of a particular structure of the musculoskeletal system. IN upper section the gyrus projected the lower limb, in the middle - the trunk and upper limb, in the lower - the neck and head. The human figure (Fig. 30, B) is projected into this gyrus with a huge face and mouth, a hand and especially a thumb, a small body and a very small leg.

Figure: 30. Scheme of the sensitive (A) and motor (B) homunculi: 1 - gyrus postcentralis; 2 - gyrus precentralis; 3 - ventriculus lateralis

4. The cortical nucleus of targeted complex combined movements (the nucleus of praxia, from praxis - practice) is located in the inferior parietal lobe within the gyrus supramarginalis. The function of this core is due to its large associative connections. His defeat does not lead to paralysis, but excludes the possibility of performing practical (labor, professional) movements.

5. The cortical nucleus of the combined rotation of the head and eyes in the opposite direction is located in the posterior part of the middle frontal gyrus, which is part of the premotor zone.

The cortical nucleus of the olfactory analyzer is located in the uncus et

7. The cortex of the hippocampus taste analyzer (fig. 29)

8. The cortical nucleus of the visual analyzer is located on the medial surface of the occipital lobe of the cerebral hemispheres along the edges of the sulcus calcarinus, within the cuneus, gyrus occipitotemporalis medialis seu lingualis (Fig. 27). In each hemisphere within the nucleus, the receptors of the lateral half of the retina of the given side and the medial half of the retina of the opposite side are projected.

9. The cortical nucleus of the auditory analyzer is located in the middle section of the superior temporal gyrus (Heschl's gyrus), facing the islet. Nerve impulses from the receptors of the hearing organs of the left and right sides enter the nucleus.

10. The cortical nucleus of the statokinetic (vestibular) analyzer is located in the middle parts of the lower and middle temporal gyri.

11. Cortical nuclei of speech analyzers. In humans, these nuclei were formed in connection with the development of the second signal system (oral and written speech) based on associative connections with the cortical nuclei of vision and hearing (Fig. 28).

a) The nucleus of the motor analyzer of oral speech (speech articulation), Broca's center (P. Broca), is located in the posterior part of the inferior frontal gyrus in the pars triangularis. The defeat of this nucleus leads to the loss of the ability to pronounce words, although the ability to pronounce sounds and sing is preserved. This phenomenon is called motor aphasia.

b) The nucleus of the auditory analyzer of oral speech, the center of Wernicke (K. Wernicke), is located in the posterior part of the superior temporal gyrus, deep in the lateral groove in close proximity to the nucleus of the auditory analyzer. The defeat of the nucleus leads to the disappearance of the ability to understand sounding speech and control the pronunciation of words, verbal deafness, or sensory aphasia, occurs. However, the auditory perception of sounds remains.

c) The cortical nucleus of the motor analyzer of written speech is located in the posterior part of the middle frontal gyrus, which is adjacent to that part of the precentral gyrus cortex, from which the work of the muscles of the hand, in particular the hand, providing the writing of letters and other signs, is regulated.

The defeat of this nucleus leads to agraphia - the impossibility of performing precise and subtle movements necessary for writing letters, numbers and words.

d) The cortical nucleus of the visual analyzer of written speech is localized in the angular gyrus of the inferior parietal lobe, in the gyrus angularis, in close proximity to the nucleus of the visual analyzer. In the event of a defeat of this nucleus, the person's ability to perceive the written text disappears, that is, to read. This phenomenon is called alexia.

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Human midbrain

Midbrain is an ancient section of the brain included in its trunk. It includes an ancient visual center. The midbrain is located below the cerebral cortex and above the hindbrain, as if in the very center of the brain. Caudally, the midbrain is adjacent to the hindbrain, and rostrally to the diencephalon. In the ventral part of the midbrain are the so-called legs of the brain, most of which is occupied by pyramidal paths. In the midbrain, between the legs, there is an interperal fossa, from which the third oculomotor nerve originates. The posterior perforated substance is located deep in the inter-pectoral fossa.

The midbrain includes: midbrain roof (tectum), inferior tubercle (inferior colliculus), colliculus (superior colliculi), cerebral legs (cerebral peduncle), midbrain tegmentum (midbrain tegmentum), black matter (substantia nigra), brain stem (crus cerebri). It should be noted that there is no visible border with the diencephalon.

The midbrain is part of the brainstem. The substantia nigra of the midbrain is closely related to the musculoskeletal system of the basal ganglia pathways. In the substantia nigra and in the ventral part of the tire, dopamine is produced, which plays an important role in motivation and arousal. The midbrain transmits visual and auditory information.

Quadruple

The quadruple of the midbrain consists of two pairs of lower and upper mounds. The upper pairs are visual and the lower pairs are auditory. the upper pairs of mounds are somewhat larger than the lower pairs. These hillocks have a connection with structures of the diencephalon called the geniculate bodies. In this case, the upper mounds are associated with the lateral ones, and the lower mounds with the medial ones. The trochlear nerve emerges from the posterior surface of the midbrain. The four hard lobes help to cross several optic fibers at right angles. The auditory nuclei are located inside the lower mounds.

Cerebral legs

The cerebral pedicles are paired structures that are located on the ventral side of the cerebral aqueduct. They transfer the tegmentum to the dorsal side. The middle part of the brain contains a black substance, which is a type of basal nucleus. The substantia nigra is the only part of the brain that contains melanin. Between the legs there is an inter-pectoral fossa.

The structure of the midbrain, its functions and features

which is filled with cerebrospinal fluid, is like a flush cistern. The oculomotor nerve extends between the legs, while the trochlear nerve flows around the outer sides of the legs.

The oculomotor nerve (parasympathetic) is responsible for the constriction of the pupil and some eye movements.

The structure of the midbrain in sections

With a horizontal section of the midbrain at the level of the upper mound, there is a red nucleus, the nuclei of the oculomotor nerve and the associated nuclei of Edinger-Westphal, the cerebral legs, as well as the substantia nigra.

With a horizontal section of the midbrain at the level of the lower mound, a black matter is also observed, the nuclei of the trochlear nerve and the crosshair of the upper cerebellar legs are also clearly visible.

In both cases, there is a cerebral aqueduct connecting the third and fourth ventricles and the periaqueductal gray matter.

Midbrain development

During embryonic development, the midbrain is formed from the second vesicle. It remains indivisible during further development, in contrast to the other two vesicles of the forebrain and hindbrain. The division into other areas of the brain does not occur during the development of the nervous system, unlike the forebrain, which is divided into the telencephalon and diencephalon.

During embryonic development in the midbrain, there is a continuous development of nerve cells, which are gradually compressed by the cerebral aqueduct. In some cases (with impaired development), partial or complete blockage of the cerebral aqueduct may occur, which leads to congenital hydrocephalus.

Midbrain consists of:

Bugrov quadruple,

Red core,

Substance black

Seam nuclei.

Red core - provides the tone of skeletal muscles, redistribution of tone when changing posture. Just stretching is a powerful work of the brain and spinal cord, for which the red nucleus is responsible. The red core ensures the normal tone of our muscles. If the red nucleus is destroyed, decerorative stiffness occurs, while the tone in some animals of the flexors increases sharply, in others - the extensors. And with absolute destruction, both tones increase at once, and it all depends on which muscles are stronger.

Black substance - How is excitation from one neuron transmitted to another neuron? Arousal occurs - this is a bioelectric process. He reached the end of the axon, where it stands out chemical substance - a mediator. Each cell has its own mediator. In the substantia nigra in nerve cells, a mediator is produced dopamine... With the destruction of the substantia nigra, Parkinson's disease occurs (the fingers, the head are constantly trembling, or there is stiffness as a result of a constant signal going to the muscles) because there is not enough dopamine in the brain. The substantia nigra provides subtle instrumental movements of the fingers and affects all motor functions. The substantia nigra has an inhibitory effect on the motor cortex through the stripolar system. In case of violation, it is impossible to perform subtle operations and Parkinson's disease (stiffness, tremor) occurs.

Above - the front hillocks of the quadruple, and below - the posterior hillocks of the quadruple. We look with our eyes, but we see with the occipital cortex of the cerebral hemispheres, where the visual field is located, where the image is formed. A nerve leaves the eye, passes through a series of subcortical formations, reaches the visual cortex, there is no visual cortex, and we will not see anything. Anterior tubercles of the quadruple Is the primary visual area. With their participation, an orientation reaction to the visual signal arises. An indicative reaction is "what is reaction?" If the anterior hillocks of the quadruple are destroyed, vision will be preserved, but there will be no quick reaction to the visual signal.

Rear tubercles of the quadruple Is the primary auditory zone. With her participation, an indicative reaction to a sound signal arises. If you destroy the posterior tubercles of the quadruple, the hearing will be preserved but there will be no orienting reaction.

Seam core Is the source of another mediator serotonin... This structure and this mediator takes part in the process of falling asleep. If the nuclei of the seam are destroyed, then the animal is in a constant state of wakefulness and quickly dies. In addition, serotonin takes part in learning with positive reinforcement (this is when a rat is given cheese). Serotonin provides such character traits as unforgettableness, benevolence, and in aggressive people a lack of serotonin in the brain.

12) Thalamus is a collector of afferent impulses. Specific and non-specific nuclei of the thalamus. The thalamus is the center of pain sensitivity.

Thalamus - visual hillock. They were the first to find in him a relation to visual impulses. It is a collector of afferent impulses, those that come from receptors. The thalamus receives signals from all receptors except olfactory receptors. The thalamus receives infa from the bp cortex from the cerebellum and from the basal ganglia. At the level of the thalamus, these signals are processed, only the most important information for a person at the moment is selected, which then enters the cortex. The thalamus consists of several dozen nuclei. Thalamic nuclei are divided into two groups: specific and non-specific. Through specific nuclei of the thalamus, signals arrive strictly to certain areas of the cortex, for example, the visual to the occipital, auditory to the temporal lobe. And through nonspecific nuclei, information comes diffusely to the entire cortex in order to increase its excitability, in order to more clearly perceive specific information. They prepare the bp bark for the perception of specific information. The highest center of pain sensitivity is the thalamus. The thalamus is the highest center of pain sensitivity. Pain is formed necessarily with the participation of the thalamus, and when some nuclei of the thalamus are destroyed, pain sensitivity is completely lost, when other nuclei are destroyed, barely tolerable pain occurs (for example, phantom pains are formed - pain in an absent limb).

13) The hypothalamic-pituitary system. The hypothalamus is the center of endocrine system regulation and motivation.

The hypothalamus with the pituitary gland form a single hypothalamo-pituitary system.

Hypothalamus.The pituitary pedicle departs from the hypothalamus, on which it hangs pituitary - the main endocrine gland. The pituitary gland regulates the work of other endocrine glands. The hypotlamus is associated with the pituitary gland by nerve pathways and blood vessels. The hypothalamus regulates the work of the pituitary gland and, through it, the work of other endocrine glands. The pituitary gland is divided into adenohypophysis (glandular) and neurohypophysis... In the hypothalamus (this is not an endocrine gland, this is a part of the brain) there are neurosecretory cells in which hormones are secreted. This is a nerve cell, it can be excited, it can be inhibited, and at the same time hormones are secreted in it. An axon departs from it. And if these are hormones, they are released into the blood, and then goes to the organs of the decision, that is, to the organ whose work it regulates. Two hormones:

- vasopressin - promotes the retention of water in the body, it acts on the kidneys, with its lack, dehydration occurs;

- oxytocin - is produced here, but in other cells, provides contraction of the uterus during childbirth.

Hormones are secreted in the hypothalamus and secreted by the pituitary gland. Thus, the hypothalamus is connected to the pituitary gland by nerve pathways. On the other hand: nothing is produced in the neurohypophysis, hormones come here, but the adenohypophysis has its own glandular cells, where a number of important hormones are produced:

- ganadotropic hormone - regulates the work of the sex glands;

- thyroid-stimulating hormone - regulates the thyroid gland;

- adrenocorticotropic - regulates the work of the adrenal cortex;

- growth hormone, or a growth hormone, - ensures the growth of bone tissue and the development of muscle tissue;

- melanotropic hormone - is responsible for pigmentation in fish and amphibians, in humans it affects the retina.

All hormones are synthesized from a precursor called proopiomellanocortin... A large molecule is synthesized, which is cleaved by enzymes, and other hormones, smaller in the number of amino acids, are released from it. Neuroendocrinology.

The hypothalamus contains neurosecretory cells. They produce hormones:

1) ADH (antidiuretic hormone regulates the amount of urine excreted)

2) oxytocin (provides contraction of the uterus during childbirth).

3) statins

4) liberins

5) thyroid-stimulating hormone affects the production of thyroid hormones (thyroxine, triiodothyronine)

Thyroliberin -\u003e thyroid-stimulating hormone -\u003e thyroxine -\u003e triiodothyronine.

The blood vessel enters the hypothalamus, where it branches into capillaries, then the capillaries are collected and this vessel passes through the pituitary pedicle, branches again in the glandular cells, leaves the pituitary gland and carries with it all these hormones, which each go with blood to their own gland. Why is this "wonderful vascular network" needed? There are nerve cells in the hypothalamus that end in the blood vessels of this wonderful vasculature. These cells produce statins and liberins - this is neurohormones. Statins inhibit the production of hormones in the pituitary gland, and liberins it is amplified. If an excess of growth hormone occurs, gigantism occurs, this can be stopped with the help of samatostatin. On the contrary: the dwarf is injected with samatoliberin. And apparently there are such neurohormones for any hormone, but they are not still discovered. For instance, thyroid, thyroxine is produced in it, and in order to regulate its production in the pituitary gland, thyrotropic hormone, and in order to control thyroid-stimulating hormone, thyrostatin was not found, but thyroliberin is used perfectly. Although these are hormones, they are produced in nerve cells, therefore, in addition to endocrine effects, they have a wide range of extra-endocrine functions. Thyreoliberin is called panaktivin, because it improves mood, increases efficiency, normalizes blood pressure, accelerates healing in case of spinal cord injuries, only it cannot be used for disorders in the thyroid gland.

Functions associated with neurosecretory cells and cells that produce neurofebtides have been discussed previously.

In the hypothalamus, statins and liberins are produced, which are included in the body's stress response. If the body is affected by some harmful factor, then the body must somehow respond - this is the stress response of the body. It cannot proceed without the participation of statins and liberins, which are produced in the hypothalamus. The hypothalamus is necessarily involved in the response to stress.

The next function of the hypothalamus is:

It contains nerve cells that are sensitive to steroid hormones, that is, sex hormones to both female and male sex hormones. It is this sensitivity that ensures the formation of a female or male type. The hypothalamus creates conditions for the motivation of male or female behavior.

A very important function is thermoregulation; the hypothalamus contains cells that are sensitive to blood temperature. Body temperature can vary depending on the environment. Blood flows through all structures of the brain, but thermoreceptive cells, which detect the slightest changes in temperature, are located only in the hypothalamus. The hypothalamus turns on and organizes two responses of the body, or heat production, or heat transfer.

Food motivation. Why does a person feel hungry?

Signal system - this is the blood glucose level, it should be constant ~ 120 milligrams%.

There is a self-regulation mechanism: if our blood glucose level decreases, liver glycogen begins to split. On the other hand, glycogen stores are insufficient. The hypothalamus contains glucose-receptor cells, which are cells that register blood glucose levels. Glucose-receptor cells form hunger centers in the hypothalamus. When blood glucose levels drop, these cells, which are sensitive to blood glucose levels, become energized and feel hungry. At the level of the hypothalamus, only food motivation arises - a feeling of hunger, the cerebral cortex must be connected to search for food, with its participation a true food reaction arises.

The satiety center is also located in the hypothalamus, it inhibits hunger, which protects us from overeating. With the destruction of the saturation center, overeating occurs and, as a result, bulimia.

The hypothalamus also contains the center of thirst - osmoreceptive cells (osmotic pressure depends on the concentration of salts in the blood) Osmoreceptive cells register the level of salts in the blood. With an increase in blood salts, osmoreceptive cells are excited, and drinking motivation (reaction) arises.

The hypothalamus is the highest center of regulation of the autonomic nervous system.

The anterior parts of the hypothalamus mainly regulate the parasympathetic nervous system, the posterior ones regulate the sympathetic nervous system.

The hypothalamus provides only motivation and purposeful behavior of the cerebral cortex.

14) Neuron - features of structure and functions. Differences between neurons and other cells. Glia, blood-brain barrier, cerebrospinal fluid.

I First, as we have already noted, in their diversity... Any nerve cell consists of a body - catfish and appendages... Neurons are different:

1.size (from 20 nm to 100 nm) and the shape of the soma

2. by the number and degree of branching of short processes.

3.on the structure, length and branching of axonal endings (laterals)

4.by the number of spines

IINeurons also differ in functions:

and) perceiving information from the external environment,

b) transmitting information to the periphery,

in) processing and transmitting information within the central nervous system,

d) exciting,

e) brake.

IIIDiffer in chemical composition: a variety of proteins, lipids, enzymes are synthesized and, most importantly, - mediators .

WHY, WITH WHAT FEATURES IS THIS RELATED TO?

This diversity is determined by high activity of the genetic apparatus neurons. During neuronal induction, under the influence of the growth factor of neurons, NEW GENES are turned on in the cells of the ectoderm of the embryo, which are characteristic only of neurons. These genes provide the following features of neurons ( most important properties):

A) Ability to perceive, process, store and reproduce information

B) DEEP SPECIALIZATION:

0. Synthesis of specific RNA;

1. Absence of reduplication DNA.

2. The proportion of genes capable of transcriptions, make up in neurons 18-20%, and in some cells - up to 40% (in other cells - 2-6%)

3. Ability to synthesize specific proteins (up to 100 in one cell)

4. The uniqueness of the lipid composition

C) Food privilege \u003d\u003e Dependence on the level oxygen and glucose in blood.

No tissue in the body is so dramatically dependent on the level of oxygen in the blood: 5-6 minutes of respiratory arrest and the most important structures of the brain die, and first of all, the cerebral cortex. A decrease in glucose levels below 0.11% or 80mg% - hypoglycemia may occur and then a coma.

On the other hand, the brain is fenced off from the BBB blood flow. It does not allow anything that could damage them to the cells. But, unfortunately, not all - many low-molecular toxic substances pass through the BBB. And pharmacologists always have a problem: does this drug pass through the BBB? In some cases it is necessary when it comes to diseases of the brain, in others it is indifferent to the patient if the drug does not damage nerve cells, and in still others it must be avoided. (NANOPARTICLES, ONCOLOGY).

Sympathetic NS is excited and stimulates the adrenal medulla - the production of adrenaline; in the pancreas - glucagon - breaks down glycogen in the kidneys to glucose; glucocarticoids were produced. in the adrenal cortex - provides gluconeogenesis - the formation of glucose from ...)

And yet, with all the variety of neurons, they can be divided into three groups: afferent, efferent, and intercalary (intermediate).

15) Afferent neurons, their functions and structure. Receptors: structure, function, formation of an afferent volley.