Retinal pigment epithelium. Pigment epithelium In the cornea there are:

Epithelium Epithelial cells are constantly present in urine sediment. At the same time, epithelial cells originating from different parts of the genitourinary system differ in shape and structure (flat, transitional and renal epithelium are distinguished). Cells of squamous epithelium, characteristic

The retinal pigment epithelium is a layer of cells located outside the retinal nerve membrane. It is formed by specific light-sensitive tissue elements and provides the most important functions of the eye. What functions does this retinal layer perform? Needs to be looked at in more detail.

The structure of the retina

Important functions of the pigment layer of the epithelium

The functions of the retinal pigment layer are as follows:

1. Absorption of light rays. Thanks to this function, a person can see. The pigment epithelium in the retina provides the clarity and contrast of images that can be seen by humans.
2. Phagocytosis of spent light-sensitive retinal cells. If such a function of the eye did not exist, then a person’s vision would gradually deteriorate due to the fact that a large number of dead cells accumulated on the photosensitive layer. Moreover, pigment cells absorb a large amount of waste elements per day.
3. The pigment layer uses reserves of vitamin A. This same compound is a precursor to a substance that ensures the formation of impulses that then enter the brain.
4. Transports nutrients and removes waste products.
5. Ensuring normal exchange of water and ions.
6. Heat exchange (eye temperature is regulated).
7. The importance of the retinal pigment ball for visual acuity

This shell, due to the presence of melanin in it, provides normal image contrast. There are people who have impaired formation of the melanin pigment (albinos). The epithelium in the retina contains practically no pigments.

If such a person is in a brightly lit room, his visual acuity remains very low even with normal correction. Sometimes the retinal ball may contain a large amount of waste pigment decay products. This, in turn, leads to age-related vision loss in such people.

What is Bruch's membrane? This is a light-sensitive plate. It provides selective transport of nutrients to the retina. Often, so-called drusen can form in the area of ​​such a membrane.

They are formed as a result of inevitable aging or disease. The formation of drusen disrupts metabolic processes in the retina and significantly impairs vision.

Bruch's membrane together with the choriocapillaris layer forms one complex. It provides barrier functions. A person could not see normally without the functioning of Bruch's membrane.

What is retinal pigment epithelial layer detachment?

In this case, local detachment of the macular area from the pigmented layer occurs. The patient complains about the oddness and blurriness of objects, the appearance of “fog” before the eyes. As a rule, only one eye is affected. Visual acuity in this case decreases significantly - to 0.4. The Amsler test shows the curvature of straight lines.

The edge of the peeled pigment layer is visible a little more clearly. The process certainly leads to macular degeneration and. Treatment of detachment of the pigmented epithelial layer of the retina is carried out only in an ophthalmological hospital. The following examinations are carried out:

• perimetry;
• visometry;
• ophthalmoscopy;
• Amsler grid test;
• electrocardiogram;
• angiography;
• general clinical examination of urine and blood;
• It is mandatory to conduct a clinical blood examination for the Wasserman reaction;
• study of the amount of glucose in blood plasma.

Usually treatment of the disease is conservative. Glucocorticosteroids (intraconjunctival administration), angioprotective, anti-inflammatory nonspecific drugs and some types of antihistamines are prescribed.

If there is no effect from conservative treatment, laser therapy is prescribed. It is required if the disease recurs. Laser coagulation is indicated if the issue of restoring eye function is urgent. Under favorable circumstances, patients manage to maintain their vision.

How are diseases of the pigment layer diagnosed?

All diseases of this layer of the retina are diagnosed only after a thorough ophthalmological examination. In young children, making an accurate diagnosis can be quite difficult. If you notice that the child has difficulty oriented in the twilight or at night, he should be shown to a doctor: he is probably developing the initial stage of retinal pigment layer degeneration.

Diagnosis of diseases of this element of the visual organs is carried out using the following methods:

• study of visual acuity (both normal and peripheral);
• examination of the fundus of the eye;
• electrophysiological examination;
• study of the degree of adaptation of the eye to darkness.

Prevention of diseases of the retinal pigment layer

Specific measures to prevent this disease have not been developed. This is due to the fact that most of it is hereditary. Maintaining a healthy lifestyle, giving up bad habits, moderate physical activity, and properly selected nutrition help slow down the destruction of the pigment layer and decreased vision.

Timely treatment can restore this area of ​​the eye and ensure good vision.

The pigment layer in the retina is critical for generating nerve impulses and transmitting image information to the brain. This ensures normal vision. Treatment of all diseases of the pigment layer is carried out only in an ophthalmological hospital.

Layers of the retina-

1. Pigment epithelium

2.Layer of rods and cones

3. External border plate

4. Outer nuclear layer

5. Outer mesh layer

6. Inner nuclear layer

7. Inner mesh layer

8. Ganglion cell layer

9. Nerve fiber layer

10. Internal limiting membrane

The structure of the pigment epithelium

a) Finally, behind the layer of rods and cones there is, as we know, a layer pigment epithelium(1) the retina (or the pigment layer of the retina), located on the basement membrane.

b) Pigment epithelial cells have

processes enclosing the outer segments of rods and cones

(3-7 processes around each rod and up to 30-40 around the cone).

c) The pigment in cells is contained in melanosomes.

Functions pigment epithelium:

absorption of excess light (which was already noted in paragraph 16.2.1.2.III),

supplying photoreceptor cells with retinol (vitamin A), which is involved in the formation of light-sensitive proteins - rhodopsin and iodopsin,

phagocytosis waste components of rods and cones (clause 16.2.5.5)

The innervation of the striated muscles, smooth muscles and glands is disrupted.

Option 4

1) Sensitive nerve nodes are located along the dorsal roots of the spinal cord and cranial nerves. The source of origin is nerve fibers. Pseudounipolar neurons are located in the spinal ganglia, which are characterized by a spherical body, a light nucleus, large and small cells are distinguished according to the conductivity of impulses. 2) The posterior horns contain several nuclei, formed by multipolar interneurons on which the axons of pseudounipolar cells of the spinal ganglia end, which carry information from the receptors. Axons of interneurons: end in the gray matter of the spinal cord, form intersegmental connections in the gray matter of the spinal cord, exit into the white matter of the spinal cord and form ascending and descending pathways, some of them pass to the opposite side of the spinal cord.

The intermediate zone of gray matter of the spinal cord is located between the anterior and posterior horns. Here, from the 8th cervical to the 2nd lumbar segment, there is a protrusion of gray matter - the lateral horn. In the medial part of the base of the lateral horn, a difficult nucleus consisting of large nerve cells is noticeable, well outlined by a layer of white matter. This nucleus extends along the entire posterior column of gray matter in the form of a cellular cord (Clark's nucleus). The largest diameter of this nucleus is at the level from 11 thoracic to 1 lumbar segment. The lateral horns contain the centers of the sympathetic part of the autonomic nervous system in the form of several groups of small nerve cells united in the lateral intermediate (gray) substance. The axons of these cells pass through the anterior horn and exit the spinal cord as part of the ventral roots. In the intermediate zone there is a central intermediate (gray) substance, the cell processes of which participate in the formation of the spinocerebellar tract. At the level of the cervical segments of the spinal cord, between the anterior and posterior horns, and at the level of the upper thoracic segments, between the lateral and posterior horns, a reticular formation is located in the white matter adjacent to the gray matter. The reticular formation here looks like thin bars of gray matter intersecting in different directions and consists of nerve cells with a large number of processes.

3) Functional devices of the eyeball a) Refractive (cornea, aqueous humor, lens, stele) b) Accommodative (iris, ciliary body) c) Receptive (retina) The lens is a biconvex body, held in place by the fibers of the ciliary girdle, consisting of a lens capsule - a transparent layer covering the lens from the outside, Lens epithelium is a layer of cubic cells, lens fibers are hexagonal-shaped epithelial cells lying parallel to the surface of the lens. When the anterior roots are damaged, paresis and atrophy of the cervical muscles occur,

The innervation of striated, smooth muscle tissue and glands is disrupted.

Option 5

1) Since the spinal ganglion has a fusiform shape and is covered with a capsule from dense fibrous connective tissue, a cluster of bodies of pseudounipolar neurons is located along its periphery. From the body of a pseudounipolar neuron, a process extends, dividing in a T-shape, into 2 branches, afferent and efferent. The afferent ends at the periphery with receptors. THE EFFERENT ENTERS AS A COMPOSITION OF THE POSSIBLE ROOT INTO THE SPINAL CORD. 2) The granular layer of the cerebellum contains cell bodies of granules, large granule cells, cerebellar glomeruli - synaptic contact zones, between mossy fibers, dendrites of granule cells. Granule cells—small neurons with poorly developed organelles and short dendrites—axons are sent to the molecular layer, where they divide in a T-shape into 2 branches, forming excitatory synapses on the dendrites of the cells. Large grain cells contain well-developed organelles. Axons form synapses in the dendrites of granule cells, and long ones rise into the molecular layer. There are large stellate neurons of types 1 and 2. The vast majority of Golgi cells are type 1, the dendrites of which are directed into the molecular layer, forming synapses with axons. Golgi cells of type 2, their dendrites are not numerous, are highly branched and form contacts with collateral axons of piriform neurons. 3) The lower wall of the membranous canal of the cochlea is The basilar plate, which forms the bottom of the canal, is lined with single-layer squamous epithelium on the side of the scala tympani. It consists of an amorphous substance containing collagen fibers that form 20 thousand auditory strings stretched from the spiral ligament to the spiral bone plate. The strings perceive sound in the range of 16-20 thousand hertz. The spiral organ is formed by receptor sensory epithelial cells and supporting cells. Sensory epithelial cells are divided into 2 types: internal hair cells (pear-shaped, located in 1 row and surrounded by internal phalangeal cells), external hair cells (prismatic-shaped, lie in cup-shaped depressions of the external phalangeal cells). Supporting cells are divided into (Pillar cells, phalangeal cells, border, outer supporting cells, Böttcher cells)

TASK—The occipital lobes of the brain determine the capabilities of the human visual system. Damage to this area can lead to partial loss of vision or even complete blindness. Type of bark - agranular

Option 6

1) Peripheral nerves consist of bundles of myelin and b esmyelinated nerve fibers, single neurons or their clusters and sheaths. The cell bodies of neurons are located in the gray matter of the spinal cord and brain and the spinal ganglia. The nerves contain sensory (afferent) and motor (efferent) nerve fibers, but most often both. Between the nerve fibers there is an endoneurium, represented by delicate layers of loose fibrous connective tissue with blood vessels. 2) The intermediate zone of the gray matter of the spinal cord is located between the single and posterior horns. Here, from the 8th cervical to the 2nd lumbar segment, there is a protrusion of gray matter - the lateral horn. In the medial part of the base of the lateral horn, a difficult nucleus consisting of large nerve cells is noticeable, well outlined by a layer of white matter. This nucleus extends along the entire posterior column of gray matter in the form of a cellular cord (Clark's nucleus). The largest diameter of this nucleus is at the level from 11 thoracic to 1 lumbar segment. The lateral horns contain the centers of the sympathetic part of the autonomic nervous system in the form of several groups of small nerve cells united in the lateral intermediate (gray) substance. The axons of these cells pass through the anterior horn and exit the spinal cord as part of the ventral roots. In the intermediate zone there is a central intermediate (gray) substance, the cell processes of which participate in the formation of the spinocerebellar tract. At the level of the cervical segments of the spinal cord, between the anterior and posterior horns, and at the level of the upper thoracic segments, between the lateral and posterior horns, a reticular formation is located in the white matter adjacent to the gray matter. The reticular formation here looks like thin bars of gray matter intersecting in different directions and consists of nerve cells with a large number of processes. 3) The peripheral section of the vestibular analyzer, located in bony labyrinth of the inner ear (represented by the saccule, utricle and ampullae of the semicircular canals) The ampullae of the semicircular canals form protrusions, ampullary ridges, located perpendicular to the axis of the canal. The ridges are lined with prismatic epithelium. The total number of hair cells is 16-17 thousand. Stereocilia and kinocilia are immersed in a layer of gelatinous substance without otoliths. Functions - Ampullary crests perceive angular accelerations.

4) With pathology of the spiral ganglion, the electrical potential will be perceived, which is transmitted at the end of the bipolar cells of the spiral ganglion (their axons form the cochlear nerve), which leads to hearing impairment.

Option-7 1) 1…..SPINAL NODES (SPINAL GANGLIA) - laid in the embryonic period from the ganglion plate (neurocytes and glial elements) and mesenchyme (microgliocytes, capsule and SDT layer). The spinal ganglia (SNG) are located along the dorsal roots of the spinal cord. The outside is covered with a sdt capsule; layers-partitions of loose sdt with blood vessels extend from the capsule inwards. The bodies of neurocytes are located in groups under the capsule. SMU neurocytes are large, their body diameter is up to 120 µm. The nuclei of neurocytes are large, with distinct nucleoli, located in the center of the cell; Euchromatin predominates in the nuclei. The bodies of neurocytes are surrounded by satellite cells or mantle cells - a type of oligodendrogliocytes. SMU neurocytes are pseudounipolar in structure - the axon and dendrite extend from the cell body together as one process, then diverge in a T-shape. The dendrite goes to the periphery and forms sensitive receptor endings in the skin, in the thickness of tendons and muscles, in internal organs that perceive pain, temperature, tactile stimuli, i.e. SMU neurocytes are sensitive in function. Axons along the dorsal root enter the spinal cord and transmit impulses to the associative neurocytes of the spinal cord. In the central part of the SMU, nerve fibers covered with lemmocytes are located parallel to each other. 2)…… Purkinje cells form the middle ganglion layer cerebellum. The cell bodies are pear-shaped, located at approximately the same distance from each other, forming a row in one layer. From the body of the neuron, 2-3 dendrites extend into the molecular layer, which intensively branch and occupy the entire thickness of the molecular layer. The terminal branches of the dendrites end in spines The spine is a collateral of the dendrite to provide contacts. The spine has a thin “leg” that ends in a “button”. All dendrites of one Purkinje cell contain over 90 thousand spines. Dendrites with their spines form contacts with climbing fibers, axons of granule cells of the inner layer, axons of stellate neurons of the molecular layer. An axon departs from the lower pole of the piriform neuron, which, after passing through the granular layer of the cortex, enters the white matter of the cerebellum and goes to the cerebellar nuclei, where it forms synapses. Within the granular layer, a collateral departs from the axon of the Purkinje cell, which returns to the ganglion layer and entwines the body of the neighboring Purkinje cell, in the form of a basket, forming synapses. Some of the collaterals reach the molecular layer, where they contact the bodies of basket neurons. 3) Retinal neuroglia are represented by radial gliocytes(Müller cells), astrocytes and microglia. Radial gliocytes (Müller cells) are large process cells that extend almost the entire thickness of the retina perpendicular to its layers. occupy almost all the spaces between neurons and their processes. With their bases they form the internal glial limiting membrane, which borders the retina from the vitreous body, and with their apical sections, due to their processes, they form the outer glial limiting membrane. Numerous lateral processes intertwine the bodies of neurons in the area of ​​synaptic connections, performing supporting and trophic functions. They also surround the capillaries, forming, together with astrocytes, the blood-retinal barrier. Astrocytes are glial cells, located mainly in the inner layers of the retina and covering capillaries with their processes (forming a blood-retinal barrier). Microglial cells are located in all layers of the retina and are few in number. Perform a phagocytic function. TASK—The occipital lobes of the brain determine the capabilities of the human visual system. Damage to this area can lead to partial loss of vision or even complete blindness. Type of bark - agranular

1) The spinal cord is distinguished between gray and white substance. On a cross section of the spinal cord, the gray matter has the shape of the letter H. The anterior (ventral), lateral, or lateral (lower cervical, thoracic, two lumbar), and posterior (dorsal) horns of the gray matter of the spinal cord are distinguished. Gray matter is represented by the bodies of neurons and their processes, nerve endings with the synaptic apparatus, macro- and microglia and blood vessels. The white matter surrounds the outside of the gray matter and is formed by bundles of pulpal nerve fibers that form pathways throughout the spinal cord. These pathways head towards or descend from the brain. This also includes fibers going to the higher or lower segments of the spinal cord. In addition, the white matter contains astrocytes, individual neurons, and hemocapillaries. In the white matter of each half of the spinal cord (on a transverse section), three pairs of columns (cords) are distinguished: posterior (between the posterior median septum and the medial surface of the dorsal horn), lateral (between the anterior and posterior horns) and anterior (between the medial surface of the anterior horn and anterior median fissure). In the center of the spinal cord there is a canal lined with ependymocytes, among which there are poorly differentiated forms that, according to some authors, are capable of migration and differentiation into neurons. In the lower segments of the spinal cord (lumbar and sacral), after puberty, proliferation of gliocytes and overgrowth of the canal occurs, the formation of an intraspinal organ. The latter contains gliocytes and secretory cells that produce a vasoactive neuropeptide. The organ undergoes involution after 36 years. The neurons of the gray matter of the spinal cord are multipolar. Among them, neurons with a few weakly branching dendrites, neurons with branching dendrites, and also transitional forms are distinguished. Depending on where the neuron processes go, there are: internal neurons, the processes of which end at synapses within the spinal cord; fascicle neurons, the neurite of which goes as part of bundles (conducting pathways) to other parts of the spinal cord or to the brain; radicular neurons, the axons of which leave the spinal cord as part of the anterior roots . 2) The agranular type of cortex is characteristic of its motor centers and is characterized by the greatest development of layers III, V, VI of the cortex with weak development of layers II and IV (granular) layers. Such areas of the cortex serve as sources of descending pathways of the central nervous system. The granular type of cortex is characteristic of areas where sensitive cortical centers are located. It is characterized by weak development of layers containing pyramidal cells, with significant expression of granular layers. 3 ) The olfactory organ is a chemoreceptor. He perceives action of odorant molecules. This is the most ancient type of reception. The olfactory analyzer consists of three parts: the olfactory region of the nasal cavity (peripheral part), the olfactory bulb (intermediate part), and also the olfactory centers in the cerebral cortex. Development of the sense of smell. The source of formation of all parts of the olfactory organ is the neural tube, symmetrical local thickenings of the ectoderm - olfactory placodes located in the area of ​​the anterior part of the head of the embryo and mesenchyme. The placode material is invaginated into the underlying mesenchyme, forming olfactory sacs connected to the external environment through openings (future nostrils). The wall of the olfactory sac contains stem cells, which in the 4th month of embryogenesis, through divergent differentiation, develop into neurosensory (olfactory) cells that support basal epithelial cells. Some of the cells of the olfactory sac go to build the olfactory (Bowman's) gland. At the base of the nasal septum, the vomeronasal (Jacobson) organ is formed, the neurosensory cells of which respond to pheromones. The structure of the sense of smell. The olfactory lining of the peripheral part of the olfactory analyzer is located on the superior and partially middle concha of the nasal cavity. Its total area is about 10 cm2. The olfactory region has an epithelial-like structure. The receptor part of the olfactory analyzer is delimited from the underlying connective tissue by the basement membrane. Olfactory neurosensory cells are spindle-shaped with two processes. Based on their shape, they are divided into rod-shaped and cone-shaped. The total number of olfactory cells in humans reaches 400 million, with a significant predominance of rod-shaped cells. The peripheral process of the olfactory neurosensory cell, 15-20 µm long, has a thickening at the end called the olfactory club. On the rounded top of the olfactory clubs there are 10-12 olfactory hairs - antennae. Their length reaches 2-3 microns. The antennae have an ultrastructure characteristic of cilia, i.e. they contain 9 peripheral and 2 central paired protofibrils extending from typical basal bodies. The antennas perform continuous automatic pendulum-type movements. The top of the antennas moves along a complex trajectory, thereby increasing the possibility of their contact with molecules of odorous substances. The antennae are immersed in a liquid medium, which is the secretion of the tubular-alveolar olfactory glands (Bowman's). They are characterized by a merocrine type of secretion. The secretion of these glands moisturizes the surface of the olfactory lining. The central process of the olfactory neurosensory cell, the axon, is directed to the intermediate part of the olfactory organ - the olfactory bulb and establishes a synaptic connection there in the form of a glomerulus with mitral neurons. The following layers are distinguished in the olfactory bulb: 1) layer of olfactory glomeruli, 2) outer granular layer, 3) molecular layer, 4) layer of mitral cells, 5) inner granular layer, 6) layer of centrifugal fibers. The central section of the olfactory organ is localized in the hippocampus and in the hippocampal gyrus of the cerebral cortex, where the axons of mitral cells are sent and form synaptic connections with neurons. Thus, the organ of smell (olfactory region of the nasal cavity and olfactory bulb), like the organ of vision, has a layered arrangement of neurons, which is characteristic of screen nerve centers. The supporting epithelial cells of the olfactory region are highly prismatic cells with microvilli, located in the form of a multirow epithelial layer, providing spatial organization of neurosensory cells. Some of these cells are secretory and also have phagocytic ability. Cuboidal basal epithelial cells are poorly differentiated (cambial) and serve as the source of the formation of new cells of the olfactory lining.

The dorsal horns contain several nuclei formed by multipolar interneurons of small and medium sizes, on which the axons of the preunipolar cells of the spinal ganglia end. Axons of interneurons end in the gray matter of the spinal cord on motor neurons lying in the anterior horns; form intersegmental connections within the gray matter of the spinal cord; exit into the white matter of the spinal cord, where they form ascending and descending pathways. When damaged, the transport of these pathways is disrupted.

Option-9

1)The intermediate zone of the gray matter of the spinal cord is located between the anterior and posterior horns. Here, from the 8th cervical to the 2nd lumbar segment, there is a protrusion of gray matter - the lateral horn. In the medial part of the base of the lateral horn, a difficult nucleus consisting of large nerve cells is noticeable, well outlined by a layer of white matter. This nucleus extends along the entire posterior column of gray matter in the form of a cellular cord (Clark's nucleus). The largest diameter of this nucleus is at the level from 11 thoracic to 1 lumbar segment. The lateral horns contain the centers of the sympathetic part of the autonomic nervous system in the form of several groups of small nerve cells united in the lateral intermediate (gray) substance. The axons of these cells pass through the anterior horn and exit the spinal cord as part of the ventral roots. In the intermediate zone there is a central intermediate (gray) substance, the cell processes of which participate in the formation of the spinocerebellar tract. At the level of the cervical segments of the spinal cord, between the anterior and posterior horns, and at the level of the upper thoracic segments, between the lateral and posterior horns, a reticular formation is located in the white matter adjacent to the gray matter. The reticular formation here looks like thin bars of gray matter intersecting in different directions and consists of nerve cells with a large number of processes. 2) large, gigantic neurons, formed by large, and in the area anterior central gyrus - giant pyramidal neurons. The apical dendrites reach the molecular layer, and the lateral dendrites spread within their layer, forming numerous synapses. The axons of these cells form pyramidal tracts (tracts) reaching the nuclei of the brain stem and motor nuclei of the spinal cord

3) The taste organ is peripheral section of the taste analyzer and is located in the oral cavity. Taste receptors consist of neuroepithelial cells, contain branches of the taste nerve and are called taste buds. The taste buds are oval in shape and are located mainly in the leaf-shaped, mushroom-shaped and grooved papillae of the mucous membrane of the tongue (see section “Digestive system”). They are present in small quantities in the mucous membrane of the anterior surface of the soft palate, epiglottis and posterior wall of the pharynx. Irritations perceived by the bulbs enter the nuclei of the brain stem, and then to the region of the cortical end of the taste analyzer. Receptors are able to distinguish four basic tastes: sweet is perceived by receptors located at the tip of the tongue, bitter - by receptors located at the root of the tongue, salty and sour - by receptors at the edges of the tongue.

TASK-......

The ampullary crests perceive angular accelerations: when the body rotates, an endolymph current arises, which deflects the dome, which stimulates the hair cells due to the bending of the stereocilia. The movement of the dome towards the kinocilium causes excitation of the receptors, and in the opposite direction – their inhibition. Accordingly, during a pathological process, all these processes will be disrupted

Option 10

1)the anterior horns contain multipolar motor cells( motor neurons) with a total number of 2-3 million. Motor neurons are united into nuclei, each of which extends into several segments. I distinguish between large alpha mononeurons and smaller gamma motor neurons scattered among them.

On the processes and bodies of motor neurons there are numerous synapses that have excitatory and inhibitory effects on us. On motor neurons they end:

A) collaterals of axons of pseudounipolar cells of spiral ganglia, forming two-neuron arches with them

B) axons of interneurons

B) axons of Renshaw cells

D) Fibers of descending tracts

2) Purkinje cells form the middle ganglion layer cerebellum. The cell bodies are pear-shaped, located at approximately the same distance from each other, forming a row in one layer. From the body of the neuron, 2-3 dendrites extend into the molecular layer, which intensively branch and occupy the entire thickness of the molecular layer. The terminal branches of the dendrites end in spines The spine is a collateral of the dendrite to provide contacts. The spine has a thin “leg” that ends in a “button”. All dendrites of one Purkinje cell contain over 90 thousand spines. Dendrites with their spines form contacts with climbing fibers, axons of granule cells of the inner layer, axons of stellate neurons of the molecular layer. An axon departs from the lower pole of the piriform neuron, which, after passing through the granular layer of the cortex, enters the white matter of the cerebellum and goes to the cerebellar nuclei, where it forms synapses. Within the granular layer, a collateral departs from the axon of the Purkinje cell, which returns to the ganglion layer and entwines the body of the neighboring Purkinje cell, in the form of a basket, forming synapses. Some of the collaterals reach the molecular layer, where they contact the bodies of basket neurons.

3) The peripheral section of the auditory analyzer is located in the front part of the labyrinth of the inner ear, namely in the cochlea - a spirally winding canal that makes two and a half turns. A spiral plate extends from the central bony core of the cochlea along its entire length, protruding into the canal. Between the plate and the outer wall of the canal is stretched the main membrane, consisting of the finest elastic connective tissue fibers. On the upper side of the main plate there is a receptor apparatus of the auditory analyzer - a spiral organ.

Impair the function of descending and ascending pathways

Option 11

Option 12

1…..SPINAL NODES (SPINAL GANGLIA) - are formed in the embryonic period from the ganglion plate (neurocytes and glial elements) and mesenchyme (microgliocytes, capsule and SDT layer). The spinal ganglia (SNG) are located along the dorsal roots of the spinal cord. The outside is covered with a sdt capsule; layers-partitions of loose sdt with blood vessels extend from the capsule inwards. The bodies of neurocytes are located in groups under the capsule. SMU neurocytes are large, their body diameter is up to 120 µm. The nuclei of neurocytes are large, with distinct nucleoli, located in the center of the cell; Euchromatin predominates in the nuclei. The bodies of neurocytes are surrounded by satellite cells or mantle cells - a type of oligodendrogliocytes. SMU neurocytes are pseudounipolar in structure - the axon and dendrite extend from the cell body together as one process, then diverge in a T-shape. The dendrite goes to the periphery and forms sensitive receptor endings in the skin, in the thickness of tendons and muscles, in internal organs that perceive pain, temperature, tactile stimuli, i.e. SMU neurocytes are sensitive in function. Axons along the dorsal root enter the spinal cord and transmit impulses to the associative neurocytes of the spinal cord. In the central part of the SMU, nerve fibers covered with lemmocytes are located parallel to each other. 2….. The granular type of cortex is characterized by strong development of the outer granular layer and the inner granular layer, they are wide with a large content of stellate-shaped neurons. The pyramidal and polymorphic layers, on the contrary, are narrow, contain few cells. In this type of cortex, afferent conductors coming from all sense organs end, therefore the granular type of cortex is called sensitive ( sensory) cortical centers. The stellate neurons of this layer of the cortex, when excited, are capable of causing a subjective reflection of the external world. And in the agranular type, wide pyramidal, ganglionic and polymorphic salts containing pyramidal and fusiform neurons are very well developed, and the outer granular and inner granular layers are narrow with a small number of neurons. This type of cortex has motor cortical centers. Such a center is the anterior central gyrus in which the two fields – 4 and 6. In these fields, the cortex is built according to the agranular type. In field 4, in the ganglion layer of the cortex, there are giant pyramidal neurons (Betz cells up to 150 µm.) There are no more Betz cells in any other field of the cortex. 3 …..Peripheral part of the auditory The analyzer is located along the entire length of the cochlea, consisting of a bone canal and a membranous canal located in it. The organ of hearing is represented by a spiral organ adjacent to the basement membrane, which is part of the lower wall of the membranous canal. 4……The ampullary crests perceive angular accelerations: when the body rotates, an endolymph current arises, which deflects the dome, which stimulates the hair cells due to the bending of the stereocilia. The movement of the dome towards the kinocilium causes excitation of the receptors, and in the opposite direction – their inhibition. Accordingly, during a pathological process, all these processes will be disrupted

Pigment epithelium - The outermost layer of the retina, adjacent to the inner surface of the choroid, produces visual purple. The membranes of the finger-like processes of the pigment epithelium are in constant and close contact with the photoreceptors.

The retinal pigment epithelium is very tightly bound to Bruch's membrane. It consists of a single layer of low-prismatic 5-6-sided cells containing pigment granules. The granular cytoplasmic reticulum is located in the apical parts of the cells and consists of 4-8 parallel slits. The rest of the protoplasm is filled with elements of the agranular reticulum and mitochondria. Pigment melanin granules, the diameter of which is 1.5-3.0 microns, are surrounded by a membrane.

The histological structures of the pigment epithelium are closely related to its functions. Hexagonal pigmented epithelial cells form a monolayer of very tightly interconnected elements. Their basal surfaces are connected to the vitreous plate using numerous folds of the cell membrane, and the lateral surfaces of the pigment epithelial cells are connected to each other due to their own folds. The surfaces of pigment epithelial cells that face the rods and cones have numerous short and long cilia. Short cilia are located between the terminal sections of rods and cones. Long cilia are located between the photoreceptors.

Retinal pigment cells differ from choroidal pigment cells and are characterized by their resistance to various substances that are inappropriate for eye tissue. In the macula area, pigment epithelial cells take on a cylindrical shape and contain many pigment granules. Towards the periphery of the retina, the cells acquire a flatter shape.

According to some researchers, during the day, each pigment epithelial cell phagocytoses from 2000 to 4000 rod discs. On average, 2-3 rod disks are lysed, phagocytosed and utilized within 1 minute.

Functions of the retinal pigment epithelium: provides the so-called external hematoretinal barrier, which prevents large molecules from entering the retina from the choriocalillaris

• absorption of light
• promotes the chemical restoration of photosensitive pigment, which is provided in the light,
• constant phagocytosis of released phospholipid disks from the tips of the outer segments of rods and cones
• participates in electrogenesis and development of bioelectric reactions
• regulates and maintains water and ionic balance in the subretinal space
• participation in the production of acidic mucopolysaccharides,
• deposition of vitamin A,
• participation in lipid metabolism
• cytokine production
• ensures the processing and selective supply of nutrients and oxygen from the blood of the choriocapillaris layer, ensuring the normal functioning of photoreceptors.

In albinos, melanin synthesis is impaired, and there is almost no melanin in the pigment layer. When albinos are in a brightly lit room, the light entering the eyeball is reflected in all directions by the non-pigmented surface of the retina and underlying tissues. This results in the stimulation of a large number of rods and cones by one single beam of light, although in a healthy person only a few photoreceptors are excited. Visual acuity in albinos, even with the best optical correction, rarely exceeds 0.2-0.1 (the norm is 1.0).

During life, the pigment epithelium accumulates end products that are not completely decomposed - lipofuscin; it is also deposited between the pigment epithelium and Bruch's membrane in the form of drusen. Drusen are a sign of the development of age-related macular degeneration. Disorders of the retinal pigment epithelium also occur in retinitis pigmentosa.