Human analyzers and their meaning. peripheral - eye

vestibular analyzer. Participates in the regulation of the position and movement of the body in space, in maintaining balance, and is also related to the regulation of muscle tone.

Peripheral department The analyzer is represented by receptors located in the vestibular apparatus. They are excited by a change in the speed of rotational movement, rectilinear acceleration, a change in the direction of gravity, vibration. conductor path- vestibular nerve. brain department analyzer is located in the anterior parts of the temporal lobe of the CGM. As a result of excitation of the neurons of this section of the cortex, sensations arise that give ideas about the position of the body and its individual parts in space, helping to maintain balance and maintain a certain posture of the body at rest and during movement.

The vestibular apparatus consists of the vestibule and three semicircular channels internal ear.The semicircular canals are narrow passages correct forms located in three mutuallyperpendicular planes. top or front channel lies in the front, rear - insagittal, and external - in the horizontal plane. One the end of each the canal is flask-shaped and is called an ampulla

Excitation of receptor cells occurs due to the movement of endolymph channels.

An increase in the activity of the vestibular analyzer occurs under the influence of a change in the speed of the body.

motor analyzer. Due to the activity of the motor analyzer, the position of the body or its individual parts in space, the degree of contraction of each muscle is determined.

Peripheral department The motor analyzer is represented by proprioceptors located in muscles, tendons, ligaments and periarticular bags. conductor department consists of the corresponding sensory nerves and pathways of the spinal cord and brain. brain department The analyzer is located in the motor area of the cerebral cortex - the anterior central gyrus of the frontal lobe.

Proprioceptors are: muscle spindles found among muscle fibers, bulbous bodies (Golgi) located in tendons, lamellar bodies found in fascia covering muscles, tendons, ligaments and periosteum. A change in the activity of various proprioceptors occurs at the time of muscle contraction or relaxation. Muscle spindles are always in a state of some excitation. Therefore, nerve impulses constantly flow from muscle spindles to the central nervous system, to the spinal cord. This results in motor nerve cells- motor neurons of the spinal cord are in a state of tone and continuously send rare nerve impulses along efferent pathways to muscle fibers, ensuring their moderate contraction - tone.

Interoceptive analyzer. This analyzer of internal organs is involved in maintaining the constancy of the internal environment of the body (homeostasis).

Peripheral department formed by a variety of interoreceptors diffusely located in the internal organs. They're called visceroreceptors.

Conductor the Department includes several nerves of different functional significance that innervate the internal organs, vagus, celiac and splanchnic pelvic. brain department located in the motor and premotor area of the CG. Unlike external analyzers, the brain section of the interoceptive analyzer has significantly fewer afferent neurons that receive nerve impulses from receptors. Therefore, a healthy person does not feel the work of internal organs. This is due to the fact that afferent impulses coming from interoreceptors to the brain section of the analyzer are not converted into sensations, that is, they do not reach the threshold of our consciousness. However, upon excitation of some visceroreceptors, for example, receptors Bladder and rectum in case of stretching of their walls, there are sensations of urge to urinate and defecate.

Visceroreceptors are involved in the regulation of the work of internal organs, carry out reflex interactions between them.

Pain is a physiological phenomenon that informs us about harmful effects damaging or representing a potential hazard to the body. Painful irritations can occur in the skin, deep tissues and internal organs. These irritations are perceived nociceptors located throughout the body, with the exception of the brain. Term nociception means the process of perceiving damage.

When, upon stimulation of skin nociceptors, nociceptors of deep tissues or internal organs of the body, the resulting impulses, following the classical anatomical pathways, reach the higher parts of the nervous system and are displayed by consciousness, a sensation of pain. The complex of the nociceptive system is equally balanced in the body by the complex antinociceptive system, which provides control over the activity of structures involved in the perception, conduction and analysis of pain signals. The antinociceptive system provides a decrease in pain sensations inside the body. It has now been established that pain signals coming from the periphery stimulate the activity of various parts of the central nervous system (periaductal gray matter, raphe nuclei of the brainstem, nuclei of the reticular formation, nucleus of the thalamus, internal capsule, cerebellum, interneurons of the posterior horns of the spinal cord, etc. ) exerting a downward inhibitory effect on the transmission of nociceptive afferentation in the dorsal horns of the spinal cord.

In the mechanisms of development analgesia the greatest importance is attached to the serotonergic, noradrenergic, GABAergic and opioidergic systems of the brain. The main one, opioidergic system, formed by neurons, the body and processes of which contain opioid peptides (beta-endorphin, met-enkephalin, leu-enkephalin, dynorphin). By binding to certain groups of specific opioid receptors, 90% of which are located in the dorsal horns of the spinal cord, they promote the release of various chemicals (gamma-aminobutyric acid) that inhibit the transmission of pain impulses. This natural, natural pain-relieving system is just as important to normal functioning as the pain-signaling system. Thanks to her, minor injuries such as a bruised finger or a sprain cause severe pain only for a short time - from a few minutes to several hours, without making us suffer for days and weeks, which would happen in conditions of persisting pain until complete healing.

Human analyzers, which are a subsystem of the central nervous system (CNS), are responsible for the perception and analysis of external stimuli. Signals are perceived by receptors - the peripheral part of the analyzer, and are processed by the brain - the central part.

Departments

The analyzer is a collection of neurons, which is often called a sensory system. Any analyzer has three departments:

peripheral - sensitive nerve endings (receptors), which are part of the sense organs (vision, hearing, taste, touch);
conductive - nerve fibers, a chain of different types of neurons that conduct a signal (nerve impulse) from the receptor to the central nervous system;
central - a part of the cerebral cortex that analyzes and converts the signal into sensation.

Rice. 1. Departments of analyzers.

Each specific analyzer corresponds to a certain area of the cerebral cortex, which is called the cortical nucleus of the analyzer.

Kinds

Receptors, and accordingly analyzers, can be two kinds:

external (exteroceptors) - are located near or on the surface of the body and perceive environmental stimuli (light, heat, humidity);
internal (interoceptors) - are located in the walls of internal organs and perceive irritants of the internal environment.

Rice. 2. The location of the centers of perception in the brain.

The six types of external perception are described in the table “Human Analyzers”.

*Analyzer*	*Receptors*	*Conducting paths*	*Central departments*
Visual	Retinal photoreceptors	optic nerve	Occipital lobe of the cerebral cortex
Auditory	Hair cells of the spiral (Corti) organ of the cochlea	Auditory nerve	Superior temporal lobe
Taste	Language receptors	Glossopharyngeal nerve	Anterior temporal lobe
Tactile	Receptor cells: - on bare skin - Meissner's bodies, which lie in the papillary layer of the skin; On the hair surface - hair follicle receptors; Vibrations - Pacinian bodies	Musculoskeletal nerves, back, medulla oblongata, diencephalon
Olfactory	Receptors in the nasal cavity	Olfactory nerve	Anterior temporal lobe
Temperature	Thermal (Ruffini bodies) and cold (Krause flasks) receptors	Myelinated (cold) and unmyelinated (heat) fibers	Posterior central gyrus of the parietal lobe

Rice. 3. Location of receptors in the skin.

The internal ones include pressure receptors, the vestibular apparatus, kinesthetic or motor analyzers.

Characteristics

Analyzers, regardless of type, have a number of common properties:

high sensitivity to stimuli, limited by the threshold intensity of perception (the lower the threshold, the higher the sensitivity);
difference (differentiation) of sensitivity, which makes it possible to distinguish stimuli by intensity;
adaptation that allows you to adjust the level of sensitivity to strong stimuli;
training, manifested both in a decrease in sensitivity, and in its increase;
preservation of perception after the cessation of the stimulus;
interaction of different analyzers with each other, allowing to perceive completeness outside world.

An example of a feature of the analyzer is the smell of paint. People with a low threshold for odors will smell more strongly and respond actively (lacrimation, nausea) than people with a high threshold. The analyzers will perceive a strong odor more intensely than other surrounding odors. Over time, the smell will not be felt sharply, because. adaptation will take place. If you constantly stay in a room with paint, then the sensitivity will become dull. However, after leaving the room for fresh air, for some time you will feel the smell of paint “imagining”.

An analyzer is a system that provides perception, delivery to the brain and analysis of any type of information in it (visual, auditory, olfactory, etc.). Each analyzer of the sense organs consists of a peripheral section (receptors), a conductive section (nerve pathways) and a central section (centers that analyze this type of information).

More than 90% of information about the world around a person receives through vision.

The organ of vision of the eye consists of the eyeball and an auxiliary apparatus. The latter include eyelids, eyelashes, muscles of the eyeball and lacrimal glands. The eyelids are folds of skin lined from the inside with a mucous membrane. Tears formed in the lacrimal glands wash the anterior part of the eyeball and pass through the nasolacrimal canal into the oral cavity. An adult should produce at least 3-5 ml of tears per day, which perform a bactericidal and moisturizing role.

The eyeball has a spherical shape and is located in the orbit. With the help of smooth muscles, it can rotate in the orbit. The eyeball has three shells. The outer - fibrous, or albuminous - shell in front of the eyeball passes into a transparent cornea, and its posterior section is called the sclera. Through the middle shell - the vascular - the eyeball is supplied with blood. Ahead in the choroid there is a hole - the pupil, allowing light rays to enter the inside of the eyeball. Around the pupil, part of the choroid is colored and is called the iris. The cells of the iris contain only one pigment, and if it is small, the iris is colored blue or gray, and if there is a lot, brown or black. The muscles of the pupil dilate or constrict it, depending on the brightness of the light illuminating the eye, from approximately 2 to 8 mm in diameter. Between the cornea and the iris is the anterior chamber of the eye, filled with fluid.

Behind the iris is a transparent lens - a biconvex lens necessary for focusing light rays on the inner surface of the eyeball. The lens is equipped with special muscles that change its curvature. This process is called accommodation. Between the iris and the lens is the posterior chamber of the eye.

Most of the eyeball is filled with a transparent vitreous body. After passing through the lens and the vitreous body, the rays of light fall on the inner shell of the eyeball - the retina. This is a multilayer formation, and its three layers, facing inside the eyeball, contain visual receptors - cones (about 7 million) and rods (about 130 million). The rods contain the visual pigment rhodopsin, they are more sensitive than cones and provide black and white vision in low light. Cones contain the visual pigment iodopsin and provide color vision in good light conditions. It is believed that there are three types of cones that perceive red, green and purple colors, respectively. All other shades are determined by a combination of excitations in these three types of receptors. Under the action of light quanta, visual pigments are destroyed, generating electrical signals that are transmitted from rods and cones to the ganglionic layer of the retina. The processes of the cells of this layer form the optic nerve, which exits the eyeball through the blind spot - a place where there are no visual receptors.

Most of the cones are located directly opposite the pupil - in the so-called yellow spot, and in the peripheral parts of the retina there are almost no cones, only rods are located there.

After leaving the eyeball, the optic nerve follows the superior tubercles of the quadrigemina of the midbrain, where visual information undergoes primary processing. Along the axons of the neurons of the superior tubercles, visual information enters the lateral geniculate bodies of the thalamus, and only from there to the occipital lobes of the cerebral cortex. It is there that the visual image that we subjectively feel is formed.

It should be noted that the optical system of the eye forms on the retina not only a reduced, but also an inverted image of an object. Signal processing in the central nervous system occurs in such a way that objects are perceived in a natural position.

The human visual analyzer has amazing sensitivity. So, we can distinguish a hole in the wall with a diameter of only 0.003 mm illuminated from the inside. AT ideal conditions(air purity, calmness) the fire of a match lit on the mountain can be discerned at a distance of 80 km. A trained person (and women do it much better) can distinguish hundreds of thousands of color shades. The visual analyzer only needs 0.05 seconds to recognize an object that has fallen into the field of view.

auditory analyzer

Hearing is necessary for the perception of sound vibrations in a fairly wide range of frequencies. In adolescence, a person distinguishes sounds in the range from 16 to 20,000 hertz, but by the age of 35, the upper limit of audible frequencies drops to 15,000 hertz. In addition to creating an objective holistic picture of the surrounding world, hearing provides verbal communication between people.

The auditory analyzer includes the organ of hearing, the auditory nerve and brain centers that analyze auditory information. The peripheral part of the organ of hearing, that is, the organ of hearing, consists of the outer, middle and inner ear.

The outer ear of a person is represented by the auricle, external auditory canal and tympanic membrane.

The auricle is a cartilaginous formation covered with skin. In humans, unlike many animals, the auricles are practically motionless. The external auditory meatus is a canal 3-3.5 cm long, ending with a tympanic membrane that separates the outer ear from the middle ear cavity. The latter, which has a volume of about 1 cm3, contains the smallest bones of the human body: the hammer, anvil and stirrup. The hammer "handle" fuses with the eardrum, and the "head" is movably attached to the anvil, which is movably connected to the stirrup with its other part. The stirrup, in turn, with a wide base is fused with the membrane of the oval window leading to the inner ear. The middle ear cavity is connected to the nasopharynx through the Eustachian tube. This is necessary to equalize the pressure on both sides of the eardrum with changes in atmospheric pressure.

The inner ear is located in the cavity of the pyramid of the temporal bone. The organ of hearing in the inner ear is the cochlea - a bony, spirally twisted canal with 2.75 turns. Outside, the cochlea is washed by perilymph, which fills the cavity of the inner ear. In the canal of the cochlea there is a membranous bone labyrinth filled with endolymph; in this labyrinth there is a sound-receiving apparatus - a spiral organ, consisting of a main membrane with receptor cells and an integumentary membrane. The main membrane is a thin membranous septum that separates the cochlear cavity and consists of numerous fibers of various lengths. About 25 thousand receptor hair cells are located in this membrane. One end of each receptor cell is fixed to a main membrane fiber. It is from this end that the fiber of the auditory nerve departs. When a sound signal is received, the air column filling the external auditory meatus oscillates. These vibrations are picked up by the tympanic membrane and transmitted through the hammer, anvil and stirrup to the oval window. When passing through the sound ossicle system sound vibrations increase approximately 40-50 times and are transmitted to the perilymph and endolymph of the inner ear. Through these fluids, vibrations are perceived by the fibers of the main membrane, and high sounds cause oscillations of shorter fibers, and low ones - longer ones. As a result of fluctuations in the fibers of the main membrane, receptor hair cells are excited, and the signal is transmitted along the fibers of the auditory nerve first to the nuclei of the inferior colliculus of the quadrigemina, from there to the medial geniculate bodies of the thalamus and, finally, to the temporal lobes of the cerebral cortex, where the highest center of auditory sensitivity is located.

The vestibular analyzer performs the function of regulating the position of the body and its individual parts in space.

The peripheral part of this analyzer is represented by receptors located in the inner ear, as well as large quantity receptors located in muscle tendons.

In the vestibule of the inner ear there are two sacs - round and oval, which are filled with endolymph. In the walls of the sacs there are a large number of receptor hair-like cells. In the cavity of the sacs are otoliths - crystals of calcium salts.

In addition, in the cavity of the inner ear there are three semicircular canals located in mutually perpendicular planes. They are filled with endolymph, receptors are located in the walls of their extensions.

With a change in the position of the head or the whole body in space, the otoliths and endolymph of the semicircular tubules move, exciting the hair-like cells. Their processes form the vestibular nerve, through which information about a change in the position of the body in space enters the nuclei of the midbrain, the cerebellum, the nuclei of the thalamus, and, finally, to the parietal region of the cerebral cortex.

Tactile Analyzer

Touch is a complex of sensations that occurs when several types of skin receptors are irritated. Touch receptors (tactile) are of several types: some of them are very sensitive and are excited when the skin on the hand is pressed by only 0.1 microns, others are excited only with significant pressure. On average, there are about 25 tactile receptors per 1 cm2, but there are much more of them on the skin of the face, fingers, and tongue. In addition, the hairs that cover 95% of our body are sensitive to touch. At the base of each hair is a tactile receptor. Information from all these receptors is collected in the spinal cord and, along the conducting paths of the white matter, enters the nuclei of the thalamus, and from there to the highest center of tactile sensitivity - the region of the posterior central gyrus of the cerebral cortex.

Taste Analyzer

Peripheral part of the taste analyzer - taste buds located in the epithelium of the tongue and, to a lesser extent, the mucosa oral cavity and throats. Taste buds react only to substances dissolved in water, and insoluble substances have no taste. A person distinguishes four types of taste sensations: salty, sour, bitter, sweet. Most of the receptors for sour and salty are located on the sides of the tongue, for sweet - at the tip of the tongue, and for bitter - on the root of the tongue, although a small number of receptors for any of these stimuli are scattered throughout the mucous membrane of the entire surface of the tongue. The optimal value of taste sensations is observed at a temperature in the oral cavity of 29°C.

From the receptors, information about taste stimuli through the fibers of the glossopharyngeal and partially facial and vagus nerves enters the midbrain, the nuclei of the thalamus and, finally, to the inner surface of the temporal lobes of the cerebral cortex, where the higher centers of the taste analyzer are located.

Olfactory analyzer

The sense of smell provides perception of various smells. Olfactory receptors are located in the mucous membrane of the upper part of the nasal cavity. total area, occupied by olfactory receptors, is 3-5 cm2 in humans. For comparison: in a dog this area is about 65 cm2, and in a shark it is 130 cm2. The sensitivity of the olfactory vesicles, which terminate the olfactory receptor cells in humans, is also not very high: to excite one receptor, it is necessary that 8 molecules of an odorous substance act on it, and the sensation of smell arises in our brain only when about 40 receptors are excited. Thus, a person subjectively begins to smell a smell only when more than 300 molecules of an odorous substance enter the nose. Information from the olfactory receptors along the fibers of the olfactory nerve enters the olfactory zone of the cerebral cortex, located on the inner surface of the temporal lobes.

Human analyzers (sight, hearing, smell, taste, touch)

Analyzer is a term introduced by I.P. Pavlov to designate a functional unit responsible for receiving and analyzing sensory information of any one modality.

A set of neurons of different levels of the hierarchy involved in the perception of stimuli, the conduction of excitation, and in the analysis of stimuli.

The analyzer, together with the collection specialized structures(sense organs) that contribute to the perception of environmental information is called a sensory system.

For example, the auditory system is a collection of very complex interacting structures, including the outer, middle, inner ear and a collection of neurons called the analyzer.

Often the terms "analyzer" and "sensor system" are used as synonyms.

Analyzers, like sensory systems, classify according to the quality (modality) of those sensations in the formation of which they participate. These are visual, auditory, vestibular, gustatory, olfactory, skin, vestibular, motor analyzers, analyzers of internal organs, somatosensory analyzers.

The analyzer is divided into three sections:

1. Perceiving organ or receptor designed to convert the energy of irritation into the process of nervous excitation;

2. Conductor, consisting of afferent nerves and pathways, through which impulses are transmitted to the overlying parts of the central nervous system;

3. The central section, consisting of relay subcortical nuclei and projection sections of the cerebral cortex.

In addition to the ascending (afferent) pathways, there are descending fibers (efferent), along which the regulation of the activity of the lower levels of the analyzer from its higher, especially cortical, departments is carried out.

Analyzers are special structures of the body that serve to enter external information into the brain for its subsequent processing.

Minor terms

receptors;

Block diagram of terms

In the process of labor activity, the human body adapts to environmental changes due to the regulatory function of the central nervous system (CNS). The individual is connected to the environment through analyzers, which consist of receptors, nerve pathways and a brain end in the cerebral cortex. The brain end consists of a nucleus and elements scattered throughout the cerebral cortex, providing nerve connections between individual analyzers. For example, when a person eats, he feels the taste, smell of food and feels its temperature.

If the stimulus causes pain or disruption of the analyzer, this will be the upper absolute threshold of sensitivity. The interval from minimum to maximum determines the sensitivity range (for sound from 20 Hz to 20 kHz).

In humans, receptors are tuned to the following stimuli:

electromagnetic oscillations of the light range - photoreceptors in the retina of the eye;

mechanical vibrations of air - phonoreceptors of the ear;

changes in hydrostatic and osmotic blood pressure - baro- and osmoreceptors;

Change in body position relative to the vector of gravity - receptors of the vestibular apparatus.

In addition, there are chemoreceptors (react to the effects of chemicals), thermoreceptors (perceive temperature changes both inside the body and in the environment), tactile receptors and pain receptors.

In response to changes in environmental conditions, so that external stimuli do not cause damage and death of the body, compensatory reactions are formed in it, which can be: behavioral (change of location, withdrawal of the hand from hot or cold) or internal (change in the mechanism of thermoregulation in response to change in microclimate parameters).

A person has a number of important specialized peripheral formations - sensory organs that ensure the perception of external stimuli affecting the body. These include the organs of sight, hearing, smell, taste, touch.

Do not confuse the concepts of "sense organs" and "receptor". For example, the eye is the organ of vision, and the retina is the photoreceptor, one of the components of the organ of vision. The sense organs alone cannot provide sensation. For the occurrence of a subjective sensation, it is necessary that the excitation that has arisen in the receptors enters the corresponding section of the cerebral cortex.

visual analyzer includes the eye, optic nerve, visual center in the occipital part of the cerebral cortex. The eye is sensitive to the visible range of the spectrum of electromagnetic waves from 0.38 to 0.77 microns. Within these limits, different wavelength ranges cause different sensations (colors) when exposed to the retina:

The adaptation of the eye to the distinction of a given object under given conditions is carried out by three processes without the participation of the human will.

Accommodation- changing the curvature of the lens so that the image of the object is in the plane of the retina (focusing).

Convergence- rotation of the axes of vision of both eyes so that they intersect at the object of difference.

Adaptation- adaptation of the eye to a given level of brightness. During the period of adaptation, the eye works with reduced efficiency, so it is necessary to avoid frequent and deep re-adaptation.

Hearing- the ability of the body to receive and distinguish sound vibrations with an auditory analyzer in the range from 16 to 20,000 Hz.

Smell- the ability to perceive odors. The receptors are located in the mucous membrane of the upper and middle nasal passages.

Man possesses varying degrees sense of smell to various odorous substances. Pleasant odors improve a person's well-being, while unpleasant ones act depressingly, cause negative reactions up to nausea, vomiting, fainting (hydrogen sulfide, gasoline), can change skin temperature, cause disgust for food, lead to depression and irritability.

Taste- a sensation that occurs when certain water-soluble chemicals are exposed to taste buds located on different parts of the tongue.

Taste is made up of four simple taste sensations: sour, salty, sweet, and bitter.

Functions and types of human analyzers (Table)

All other flavor variations are combinations of basic sensations. Various plots tongues have different sensitivity to taste substances: the tip of the tongue is sensitive to sweet, the edges of the tongue - to sour, the tip and edge of the tongue - to salty, the root of the tongue - to bitter. The mechanism of perception of taste sensations is associated with chemical reactions. It is assumed that each receptor contains highly sensitive protein substances that decompose when exposed to certain flavoring substances.

Touch- a complex sensation that occurs when the receptors of the skin, the outer parts of the mucous membranes and the muscular-articular apparatus are irritated.

The skin analyzer perceives external mechanical, temperature, chemical and other skin irritants.

One of the main functions of the skin is protection. Sprains, bruises, pressures are neutralized by an elastic fatty lining and elasticity of the skin. The stratum corneum protects the deep layers of the skin from drying out and is highly resistant to various chemicals. The melanin pigment protects the skin from UV rays. The intact layer of skin is impervious to infections, while sebum and sweat create a deadly acidic environment for germs.

An important protective function of the skin is participation in thermoregulation. 80% of all body heat transfer is carried out by the skin. At high ambient temperatures, skin vessels expand and heat transfer by convection increases. At low temperatures, the vessels narrow, the skin turns pale, and heat transfer decreases. Heat is also transferred through the skin by sweating.

Secretory function is carried out through the sebaceous and sweat glands. With sebum and sweat, iodine, bromine, and toxic substances are released.

The metabolic function of the skin is participation in the regulation of the general metabolism in the body (water, mineral).

The receptor function of the skin is perception from the outside and transmission of signals to the central nervous system.

Types of skin sensitivity: tactile, pain, temperature.

With the help of analyzers, a person receives information about the outside world, which determines the work of the functional systems of the body and human behavior.

The maximum transmission rates of information received by a person with the help of various sense organs are given in Table. 1.6.1

Table 1. Characteristics of the sense organs

The conduction path of the visual vestibular analyzer

Lecture 5. Analyzers

Analyzers are neuro-sensory organs that are able to register impulses in the central part of the analyzer. For the first time, the concept of analyzers was introduced by Semenov, and he singled out 3 components of their structures in analyzers:

receptor part (heat, cold)

conducting part (auditory nerve, optic)

the central part, which is represented by a certain zone of the cerebral cortex.

In humans, visual and auditory analyzers are distinguished, in addition, vestibular, olfactory and tactile analyzers.

visual analyzer.

This is a neuro-sensory organ that is capable of registering electromagnetic rays in the visible part of the spectrum. The rays below the perception zone are called infrared, above - UV.

The receptor part of the analyzer is the retinal receptors, because sticks and cones. The conducting part is the optic nerves, which form the chiasm at the level of the midbrain. The central part is the perceiving areas of the cerebral cortex (occipital lobes).

Organ of vision.

A person is characterized by a paired organ of vision - the eyes, which lie in the orbit. The eyes are attached to the walls of the orbit by 3 pairs of oculomotor muscles. Eyes are protected by eyebrows, eyelashes, eyelids. In the upper part of the orbit above the eye is the lacrimal gland. Its secret - tears - moisten the surface of the eye, prevent it from drying out, and also contain bactericidal substances, such as lysocin, which prevents the development of bacteria on the mucous membrane. Partially, tears enter the nasal cavity through the duct.

The eye is surrounded by membranes, and the outermost shell of the eye - the albuginea, or sclera, on the front side passes into a thicker and more transparent cornea. In addition, the sclera connects with the mucous lining of the eyelid, forming the conjunctiva, which holds the eye in the orbit, and, in addition, protects the cornea from external influences.

The innermost layer of the eye is the choroid, which contains capillaries. circulatory system, because they are absent in the retina itself, i.e. the main function of the choroid is trophic.

The innermost part of the choroid is the pigment layer, where the pigments are located: fuscin and melanin. The outer segments of the rod and cone receptors are immersed in the pigment layer, so the main function of the pigment layer is to hold the rays and excite the receptors. On the front side of the eye, the choroid and the pigment layer pass into the iris, and this membrane is discontinuous and the break in it is called the pupil.

The pupil aperture can constantly change depending on the lighting. The diaphragm of the pupil changes depending on the contraction of the annular and radial muscle fibers, which are innervated by the parasympathetic system.

The innermost shell of the eye - the retina - contains receptors: rods and cones. The concentration of receptors is not the same in different parts of the eye: rods predominate on the periphery of the eye, cones - in the center of the eye, especially in the region of the so-called central fossa. Here a yellow spot is formed, i.e. the maximum concentration of cones, and here colors are most well perceived. The receptors are braided with neurons, the axons of which, gathering together, form the optic nerve.

The exit point of the optic nerve is called the blind spot.

The refractive optical structures of the eye include:

cornea

aqueous humor that fills the chambers of the eye

lens

vitreous,

and the refractive power is measured in diopters.

On the retina of each eye, due to the refractive power of the media, primarily the lens, a real, inverse and reduced image is built. A person sees in direct form thanks to the daily training of the visual analyzer and indicators from other analyzers.

The optical setting of the eye on an object that moves relative to the eye is called accommodation, and the rays reflected from the object in the norm should converge to a focus point on the retina. Accommodation is achieved by changing the refractive power of the lens. For example, if an object is close to the eyes, the ciliary muscle contracts, the zinn ligaments relax, the lens takes the form of a cylinder, its refractive power is maximum, and the rays converge to a focal point on the retina. If the object is far from the retina, the ciliary muscle relaxes, the ligaments of zinn are stretched, the lens takes a flat shape, its refractive power is minimal, and the rays converge to a focal point on the retina. It is believed that the nearest point of clear vision is at such a minimum distance from the eyes when the 2 nearest points of the object are clearly distinguishable.

The far frame of clear vision lies at infinity, but noticeable accommodation is observed only when the distance to the object does not exceed 60 meters. Very good accommodation is observed when the distance to the object becomes 20 meters.

Pathology of accommodation.

Normally, the rays converge to a focal point on the retina.

Myopia – myopia- in this case, the rays converge to a focal point up to the retina.

Causes of myopia:

congenital (the eye is larger than the norm by 2-3 mm)

deterioration of the elasticity of the ligaments, the ciliary muscle is tired and there is a spasm of accommodation.

Help biconcave glass.

farsightedness- in this case, a parallel beam of light is collected at a focal point behind the retina.

Causes:

the length of the eye is less than the norm by 2-3 mm

inelasticity of the ligaments, which is observed with age, therefore, after 40, age-related farsightedness develops.

Help biconvex glass.

Astigmatism- in this case, the curvature of the cornea is increased, and the rays do not converge at all to the focal point. Cylindrical glasses help.

Retina.

The retina of the eye is a collection of receptors (rods and cones), i.e. is the peripheral part of the visual analyzer.

The structure of the retina resembles the structure of a 3-neural network. The outer part of the receptors is immersed in the pigment layer; here, in the pigment layer, are the pigments that hold the light rays. The receptors are connected to a layer of bipolar neurons, and each such neuron is connected to only one receptor. The bipolar neurons are connected to the multipolar, and the axons of the multipolar neurons combine to form the optic nerve. And one multipolar neuron can be connected to several bipolar neurons at once. Between multipolar neurons there is a stellate cell, which connects all receptive fields into a single network.

The human eye of all land animals is inverted. This means that the beam of the set first hits the vitreous body, then the layers of neurons, and only then the receptors. Thus, scattered light reaches the retina and the receptors are not affected. In many marine animals, the eye is not inverted; scattered light hits the receptors directly. Rods and cones contain pigments that break down when exposed to light. The rods contain the pigment rhodopsin, the cones contain the pigment iodopsin.

Rhodopsin is able to decompose into retinene pigment and opsin protein under the influence of even a small amount of light. Therefore, rods provide vision at dusk.

There are 3 types of iodapsins and it decomposes under the influence of intense illumination, therefore iodapsins perceive color, and due to 3 types of this pigment, all colors of the visible part of the spectrum are perceived.

The photochemical reaction of the decomposition of rhodopsin causes depolarization of the rod membrane, and this wave of depolarization first covers bipolar neurons, and then multipolar ones. With further exposure to light, the retin pigment turns into vitamin A. The reverse synthesis of rhodopsin occurs both in the light and in the dark, but it goes faster in the dark, therefore, with prolonged exposure to bright light, or when exposed to light reflected from snow, or a lack of vitamin And there is a disease of hemeralopia, or night blindness.

Cone pathologies are associated with pathologies of color perception, tk. cones are responsible for the perception of color, hue and saturation:

partial loss of color vision

color blindness (a person cannot distinguish certain colors spectrum: red=green, yellow=blue)

complete loss of color perception (achromatic vision)

A person is characterized by vision with two eyes, or binocular vision. It allows you to correctly assess the distance to the object, assess the texture, volume, relief, and the rays reflected from one point of the object are able to focus in one place on the retinas of both eyes (identical fixation), or in different places (non-identical fixation).

Due to non-identical fixation, a person perceives relief and volume. Impulses along the optic nerves are directed to the centers in the occipital lobes, where the overall picture is formed.

auditory analyzer.

The second leading analyzer in humans. This is a neuro-sensory organ that perceives sound vibrations in a certain range from 16 thousand to 22 thousand kHz. The area below perception is infrasound, above perception is ultrasound.

The auditory analyzer consists of 3 parts:

receptor part. Represented by the mechano-receptors of the inner ear, which form the cortical organ

auditory nerves that form chiasma at the level of the pons

the central part, which includes certain centers in the temporal lobes of the cortex.

Organ of hearing.

Humans have a paired hearing organ, which includes the outer ear, middle ear, and inner ear.

The outer ear is represented by the auricle and auditory meatus. The sink provides directional sound reception. The ear canal is 2.5 cm covered with ciliated epithelium. A secret is produced in epithelial cells, especially in small unicellular glands that synthesize earwax. It performs the function of protection, because. dust settles on it, and, in addition, sulfur contains bactericidal substances that kill bacteria. In addition, the air in the ear canal is warmed and humidified. The ear canal ends with the tympanic membrane, which has a fibrous structure. sound waves the tympanic membrane is struck and the fibers of the membrane begin to vibrate, which causes the ossicles of the middle ear to vibrate.

The middle ear is a cavity filled with air, and to equalize the pressure between the middle ear and the nasopharynx, a connection occurs in the form of the Eustachian tube. The bones in the middle ear are the hammer, anvil, and stirrup. The hammer with its handle is connected to the eardrum, it is in contact with the anvil, and the anvil with the stirrup, and the surface contact area from the eardrum to the stirrup, which is located on the oval window, decreases, and this makes it possible to amplify weak sounds and weaken strong ones. Thus, the middle ear takes part in the transmission of vibrations from the eardrum to the inner ear.

The inner ear is a bony labyrinth in the form of a cochlea, which is twisted 2.5 turns in the temporal bone. The bone labyrinth communicates with the cavity of the middle ear by means of an oval and a round window, which are covered with membrane membranes, and on the membrane of the oval window there is a stirrup bone. Inside the bony labyrinth, a membranous labyrinth passes, represented by 2 membranes: the basement membrane and Reisner's membrane. At the top of the cochlea, the membranes join, but in general, these membranes divide the cochlea into 3 canals, or ladders. The canals of the inner ear are filled with fluid, the cochlear canal is filled with endolymph, and the tympanic canal and vestibule are filled with relymph. These fluids are somewhat different in composition.

The sound wave causes the ossicles of the middle ear to vibrate. Vibrations of the membrane of the oval window are observed, and these vibrations are transmitted to the fluid of the inner ear, and they are damped on the membrane of the round window, with the round window acting as a resonator. The vibrations are transmitted to the basement membrane and endolymph, and are recorded by the organ of Corti located here. The organ of Corti is the receptor part of the analyzer, which is represented by hair-like cells and these cells are located on the main membrane in several rows. These cells are closed by an integumentary membrane, which at one end is attached to the basement membrane at the base of the cochlea, while its other end is free.

Vibrations of the fluid lead to vibrations of the main membrane and to the fact that the integumentary membrane of the organ of Corti begins to irritate the hairs of the mechanoreceptors. The receptor membrane is depolarized, and a wave of depolarization travels along the auditory nerve.

The fibers of the main membrane have different thicknesses and can vibrate with different amplitudes, which ensures the differentiation of high and low sounds.

It is believed that high sounds are perceived at the base of the cochlea, and low sounds are perceived at the top of the cochlea. There are several hypotheses for the perception and frequency analysis of sound:

resonance hypothesis. It is believed that at the base of the cochlea, the basement membrane resonates with the sound wave and the integumentary membrane irritates a small group of hair-like cells.
burst hypothesis. It is believed that at the top of the cochlea, the integumentary membrane irritates entire receptive fields and a whole volley of impulses is sent to the central nervous system. It is believed that low sounds are perceived in this way.

vestibular apparatus.

vestibular analyzer.

This is a neuro-sensory organ that registers changes in the position of the body or parts of the body relative to each other. The vestibular analyzer consists of 3 parts:

mechano-receptors of the vestibular apparatus

vestibular branch of the auditory nerve

central part in the temporal bone

The vestibular apparatus (c.a) lies in the temporal bone and is associated with the bony labyrinth of the inner ear, although c.a. and the cochlea of the inner ear have completely different origins.

V.a. It is represented by a bony labyrinth filled with fluid, inside which passes a membranous labyrinth, also filled with fluid. The membranous labyrinth forms the organs of the vestibule, which are represented by round and oval sacs and 3 semicircular canals, each canal is associated with a round and oval sac. At one end of the channel is an extension, or ampulla.

The vestibular organs are lined with epithelium and filled with fluid. Among the cells of the epithelium, hair-like cells are located in groups. Above the cells is a gelatinous membrane, into which the hairs of the cells are immersed.

Human analyzers

The membrane contains Ca2+ crystals called otoliths or statocysts. When moving the body or head, the oval and round sacs begin to shift relative to each other, the otoliths begin to shift, which pull the gelatinous membrane behind them and it irritates the hair-like cells.

The vestibule organs perceive the beginning and end of a rectilinear movement, rectilinear acceleration, and gravity. The semicircular canals perceive rotational movements and angular acceleration, they are filled with liquid, and hair-like cells are found only in ampoules. When the position of the body changes, the liquid filling the ampoules lags behind the walls of the ampule and irritates the hairs.

Taste analyzer.

Taste buds are located in the taste buds, which are formed on the tongue and on the oral mucosa. Impulses from the receptors go to the parietal lobes of the cerebral cortex. It is believed that the tip of the tongue perceives a sweet taste, at the root of the tongue - a bitter taste, on the sides - sour and salty.

Olfactory analyzer.

This is the only analyzer that has no representation in the cortex. Receptors are located in the nasal cavity and are able to perceive volatile compounds. These impulses are analyzed at the level of the ancient cortex, as well as through the limbic system of the brain.

Tactile analyzer.

The receptor part of this analyzer refers to the skin, where pain, heat, cold receptors are located - tactile receptors. These receptors can be free nerve endings, such as pain receptors, as well as encapsulated nerve endings, such as pressure receptors. The sensory nerves of this analyzer form a decussation at the level of the pons, and the central part of the analyzer is located in the parietal lobes of the cortex.

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Basic human analyzers

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Analyzers, sense organs and their meaning

Analyzers. All living organisms, including humans, need information about the environment. This possibility is provided to them by sensory (sensitive) systems. The activity of any sensory system begins with perception stimulus energy receptors transformation it into nerve impulses and transmission them through a chain of neurons to the brain, in which nerve impulses converted into specific sensations - visual, olfactory, auditory, etc.

Studying the physiology of sensory systems, academician I.P.

human analyzers. The main sense organs and their functions

Pavlov created the doctrine of analyzers. Analyzers are called complex nervous mechanisms by means of which the nervous system receives irritations from the external environment, as well as from the organs of the body itself and perceives these irritations in the form of sensations. Each analyzer consists of three sections: peripheral, conductive and central.

Peripheral department It is represented by receptors - sensitive nerve endings that have selective sensitivity only to a certain type of stimulus. Receptors are part of the corresponding sense organs. In complex sensory organs (vision, hearing, taste), in addition to receptors, there are also support structures, which provide a better perception of the stimulus, and also perform protective, supporting and other functions. For example, auxiliary structures of the visual analyzer are represented by the eye, and visual receptors are only sensitive cells (rods and cones). Receptors are outdoor, located on the surface of the body and perceiving irritations from the external environment, and internal, which perceive irritations from the internal organs and the internal environment of the body,

conductor department The analyzer is represented by nerve fibers that conduct nerve impulses from the receptor to the central nervous system (for example, the visual, auditory, olfactory nerve, etc.).

Central department analyzer - this is a certain area of the cerebral cortex, where the analysis and synthesis of incoming sensory information and its transformation into a specific sensation (visual, olfactory, etc.) takes place.

A prerequisite for the normal functioning of the analyzer is the integrity of each of its three departments.

visual analyzer

The visual analyzer is a set of structures that perceive light energy in the form electromagnetic radiation with a wavelength of 400 - 700 nm and discrete particles of photons, or quanta, and forming visual sensations. With the help of the eye, 80-90% of all information about the world around us is perceived.

Thanks to the activity of the visual analyzer, the illumination of objects, their color, shape, size, direction of movement, the distance at which they are removed from the eye and from each other are distinguished. All this allows you to evaluate the space, navigate in the world, perform different kinds purposeful activity.

Along with the concept of the visual analyzer, there is the concept of the organ of vision.

The organ of vision it is an eye that includes three functionally different elements:

the eyeball, in which the light-perceiving, light-refracting and light-regulating apparatuses are located;

protective devices, i.e. outer shells of the eye (sclera and cornea), lacrimal apparatus, eyelids, eyelashes, eyebrows;

the motor apparatus, represented by three pairs of eye muscles (external and internal rectus, superior and inferior rectus, superior and inferior oblique), which are innervated by III (oculomotor nerve), IV (trochlear nerve) and VI (abducens nerve) pairs of cranial nerves.

External analyzers

Reception and analysis of information is carried out with the help of analyzers. The central part of the analyzer is a certain zone in the cerebral cortex. The peripheral part is receptors that are located on the surface of the body to receive external information, or in internal organs.

external signals ® receptor ® nerve connections ® brain

Depending on the specifics of the received signals, there are: external (visual, auditory, pain, temperature, olfactory, gustatory) and internal (vestibular, pressure, kinesthetic) analyzers.

The main characteristic of analyzers is sensitivity.

The lower absolute threshold of sensitivity is the minimum value of the stimulus to which the analyzer begins to respond.

If the stimulus causes pain or disruption of the analyzer, this will be the upper absolute threshold of sensitivity. The interval from minimum to maximum determines the range of sensitivity (for example, for sound from 20 Hz to 20 kHz).

A person receives 85-90% of all information about the external environment through a visual analyzer. Reception and analysis of information is carried out in the range (light) - 360-760 electromagnetic waves. The eye can distinguish 7 primary colors and more than a hundred shades. The eye is sensitive to the visible range of the spectrum of electromagnetic waves from 0.38 to 0.77 microns. Within these limits, different wavelength ranges cause different sensations (colors) when exposed to the retina:

0.38 - 0.455 microns - purple;

0.455 - 0.47 microns - blue;

0.47 - 0.5 microns - blue;

0.5 - 0.55 microns - green;

0.55 - 0.59 microns - yellow;

0.59 - 0.61 microns - orange;

0.61 - 0.77 microns - red.

The highest sensitivity is achieved at a wavelength of 0.55 µm

The minimum intensity of light exposure that causes sensation. adaptation of the visual analyzer. The temporal characteristics of the perception of signals include: latent period - the time from the signal to the moment the sensation occurs 0.15-0.22 s .; signal detection threshold at higher brightness - 0.001 s, with flash duration - 0.1 s .; incomplete dark adaptation - from several seconds to several minutes.

Via sound signals a person receives up to 10% of the information. Auditory signals are used to focus a person's attention, to transmit information, to unload the visual system. Features of the auditory analyzer are:

- the ability to be ready to receive information at any time;

- the ability to perceive sounds in a wide range of frequencies and highlight the necessary ones;

- the ability to determine with accuracy the location of the sound source.

The perceptive part of the auditory analyzer is the ear, which is divided into three sections: outer, middle and inner. Sound waves, penetrating into the external auditory canal, vibrate the eardrum and through the chain of auditory ossicles are transmitted to the cavity of the cochlea of the inner ear. Vibrations of the fluid in the canal cause the fibers of the main membrane to resonate with the sounds entering the ear. Vibrations of the cochlear fibers set in motion the cells of the organ of Corti located in them, a nerve impulse arises, which is transmitted to the corresponding sections of the cerebral cortex. Threshold pain 130 - 140 dB.

The skin analyzer provides perception of touch, pain, heat, cold, vibration.

Human analyzers and their main characteristics.

One of the main functions of the skin is protective (from mechanical, chemical damage, from pathogenic microorganisms, etc.). An important function of the skin is its participation in thermoregulation. 80% of the entire heat transfer of the body is carried out by the skin. At a high temperature of the external environment, the skin vessels expand (heat transfer increases), at a low temperature, the vessels narrow (heat transfer decreases). The metabolic function of the skin is to participate in the processes of regulation of the general metabolism in the body (water, mineral, carbohydrate). Secretory function is provided by the sebaceous and sweat glands. Endogenous poisons, microbial toxins can be released with sebum.

The olfactory analyzer is designed for human perception of various odors (range up to 400 items). The receptors are located on the mucous membrane in the nasal cavity. The conditions for the perception of odors are the volatility of an odorous substance, the solubility of substances. Odors can signal a person about violations of technological processes.

There are four types of taste sensations: sweet, sour, bitter, salty, and other combinations of them. The absolute thresholds of the gustatory analyzer are 1000 times higher than those of the olfactory one. The mechanism of perception of taste sensations is associated with chemical reactions. It is assumed that each receptor contains highly sensitive protein substances that decompose when exposed to certain flavoring substances.

The sensitivity of the taste analyzer is rough, averaging 20%. Recovery of taste sensitivity after exposure to various stimuli ends in 10-15 minutes

Goals:

consolidate and deepen knowledge about analyzers,
give an idea of the properties of analyzer receptors through practical work,
introduce the profession of a taster,
develop logical thinking,
public speaking skills,
the ability to analyze one's own feelings,
ability to prioritize
formulate conclusions.

Equipment:

NaCl solutions at a concentration of 0.05%, 0.1%, 0.13%, 0.15%, 0.25%,
distilled water,
cups,
tea spoons,
napkins,
distribution trays,
tweezers,
opaque jars with lids containing pieces of foam rubber moistened with substances to determine the smell (Appendix 9),
coins,
tweezers,
mirrors,
mechanical alarm.

Lesson motto:“There is nothing in the mind that has not first passed through the senses.”

Board layout: Theme, motto, table: “Analyzers”, classification scheme, table on skin receptors.

During the classes

I. Org. moment.

Greetings. Discussion of the motto of the lesson: “There is nothing in the mind that has not first passed through the senses.” How do you understand these words?

Suggested answer: Receptors are the initial link of the analyzer. Perceiving signals from the environment, they convert them into electrical impulses that are transmitted to the brain. Then they are deciphered by the cerebral cortex, this is how sensations are created.

Let's formulate the topic of the lesson together (“Properties of analyzer receptors”).

II. Updating knowledge and checking d / z.

1. Frontal survey with simultaneous filling of the table:

What is an analyzer? Give a definition.

List the links of the analyzer, write them down in the top line of the table (header).

Name the analyzers known to you, write them down in column 1.

Let's check the filling and fill in the 2nd column together.

Table: "Analyzers".

Analyzers	Receptor (peripheral) department	conductor department	Central (cortical) department
1	2	3	4
Visual	Rods and cones on the retina	optic nerve	Visual area of the cerebral cortex
Auditory	Sensitive snail hairs	Auditory nerve	Auditory area of the cerebral cortex
Olfactory	Receptor cells of the nasal mucosa	Olfactory nerve	Olfactory area of the cerebral cortex
Taste	Taste buds of the oral epithelium	Facial and glossopharyngeal nerves	Taste zone of the cerebral cortex

III. New topic:

1. Classification of receptors. The role of the reticular formation.

All of the receptors we have listed perceive stimuli from the external environment. They are called exteroreceptors. Suggest where interoreceptors and proprioceptors receive signals from.

Write down the receptor classification scheme in your notebook.

Why do you think there are so many different receptors?

Suggested answer: Exteroreceptors and proprioceptors serve for orientation in space, for labor activity. Interoreceptors signal the state of the internal environment, i.e. report on the work of the kidneys, stomach, intestines.

Why do we not feel signals from our organs every second? It turns out that the activity of almost all parts of the brain is enhanced or weakened by the reticular formation. Therefore, while nothing hurts us, we do not feel how the internal organs function.

Let's imagine this situation: You are walking along the edge of a forest and suddenly you see a viper.

What are your actions at this moment? (Run away!!!) That's right, at the age of 6 I ran non-stop to the house.

And what will be the role of the reticular formation and analyzers in this example?

Suggested answer: “The cerebral cortex receives impulses from the receptors of the visual, and, possibly, auditory analyzer (if the snake hissed), the impulses were amplified by the reticular formation, at the same time all impulses from other receptors were weakened.

2. Properties of receptors (practical part).

Write down the first property in your notebook - specificity. Most analyzers are adapted to perceive only one type of stimuli, which are called adequate. Name adequate stimuli for different analyzers? (For the auditory analyzer - sound, sound waves, for the visual analyzer - light, light waves).

Experiment 1. Find out if the receptor can perceive stimuli that are not specific to it.

To this end, we will carry out the following experiment. Close eyes. On one of the eyeballs from the side of the nose, lightly press with your hand. Gently rub the eyelid. Don't open your eyes! When rubbing, many people notice the appearance of a black ring with yellowish edges. When pressed, the ring usually moves from the periphery to the center. Answer the questions:

1. Have you experienced tactile irritations? (Tactile stimuli were clearly felt: pressure was felt, displacement of the eyeball.)

2. Did skin mechanical irritations correspond to skin analyzers? (They corresponded and therefore gave accurate information about the pressure on the eye and the movement of the eyeball.)

3. Why did some of the subjects see a yellow ring during mechanical stimulation? (Mechanical stimulation of the retina of the eye caused a visual sensation.)

4. Can a receptor be excited by stimuli that are not specific to it? (Maybe, but the feeling becomes illusory, there really was no ring.)

5. Did the subjects know that the perception of the ring was apparent? (They knew because the ring was not perceived at a certain point in space, but as if it were inside the eye. In addition, its appearance and movement depended on the force of pressure on the eye).

In explaining this experience, one can dwell on the following points. First, students must understand that only stimuli that are adequate to a given analyzer have informative value. Mechanical, electrical and other stimuli that are not adequate to the visual analyzer can in some cases cause excitation of retinal receptors, nerves of the visual cortex and provoke the appearance of apparent images, but they do not carry useful information. Secondly, the processes of analysis and synthesis of excitations occurring in the cerebral cortex make it possible to correctly assess the value of the information received and make the necessary corrections. Thirdly, due to the fact that the “nervous system synthesizes information received from various analyzers, a person is able to correctly evaluate incoming information, not to confuse illusory images with real ones.

Conclude whether the receptor can perceive irritations that are not specific to it.

Formulated output: in some cases, inappropriate stimuli can cause arousal, but they do not carry useful information.

The second property is adaptation, write it down.

Experience 2. Put a coin in the palm of your hand. Time how many seconds later you stopped feeling the coin. Why?

Suggested answer: We get used to it. In the receptor, excitation weakens.

This property is called adaptation. Adaptation is the phenomenon of weakening of excitation in the receptor during prolonged action of a stimulus of constant strength. There is a decrease in sensitivity, because. increases the threshold of sensitivity. The property of adaptation is very important because the flow of impulses going to the brain decreases.

Give examples in which you can observe the adaptation of analyzers. (We do not feel the clothes on the body, hairpins, watches, rings, bracelets, we do not hear the ticking of the clock and the hum of cars at night).

The third property is sensitivity. The minimum strength of the stimulus that can cause excitation of the receptor is called the absolute threshold of sensitivity.

Different people have different sensitivity. There are people who are very sensitive. These are testers, tasters, about whom we will now listen to the message.

Student reports about tasters. (Appendix 1,2,3).

Now we will conduct a series of experiments to identify your sensitivity.

Experiment 3. For the experiment, we need a medium-sized mechanical watch and a ruler. You will work in pairs. Slowly bring the watch closer to your ear. Submit symbol partner when you hear a tick. Measure the distance from your watch to your ear. Let's create absolute silence.

High hearing acuity - at a distance of 15 cm or more. The loudness of sound is measured not in centimeters, of course, but in decibels, so often the value we received is a conventional unit. But, knowing the volume with which the clock is ticking and the distance at which the clock is removed from the ear, one can calculate the auditory sensitivity by determining the hearing threshold in decibels.

Decide on the sensitivity of your hearing.

Experience 4. Work in pairs. Take two finely sharpened pencils. A skin area is selected, for example, on the arm, which is being examined. One student simultaneously touches with pencils to different parts of the skin of the hand of another student (the second has his eyes closed). If two simultaneous injections are felt as one, it is believed that one sensitive receptor "works" on this area of \u200b\u200bthe skin. As soon as two simultaneous touches begin to feel like two, measure the distance with a ruler. It is assumed that this is minimum distance between different sensory receptors.

Draw a conclusion on what the sensitivity of skin analyzers depends on. (From the number of receptors per 1 cm 2). Consider the table "The number and distribution of heat and cold receptors on the skin" in Appendix 7.

Experiment 5. On each desk there is a tray with saline solutions of different concentrations, water, a jar for spitting, a teaspoon. Neither water nor solutions are swallowed. After determining the concentration of each solution, the mouth is rinsed with water.

NaCl solutions in concentration:

0.05% - excellent sensitivity

0.1% - good sensitivity

0.13% - satisfactory sensitivity

0.15% - poor sensitivity

0.25% - agnosia (complete or partial absence of taste sensitivity).

Experience 6. You have jars with lids on your tables. Open them, try to determine what substances are in them. If you recognize 4-5 smells out of 6, then you can become a smell taster. Make a conclusion. Do you think everyone can become tasters?

Listen to the student's message. (Appendix 4) . Make a conclusion. (Not all people can become tasters, because this is inherent in the genotype. But, if there are abilities, then they can be developed.)

3. Practical use knowledge about the sensitivity of analyzers. Conversation.

Students with reduced visual acuity or hearing should sit on desks 1-2.

Definition of quality food products- Smell, taste.

The use of perfumes, the harmonious combination of their smells.

Use when choosing a profession as an artist, musician, taster, etc.

Student report on noise pollution. (Appendix 5).

Student's message “Aroma management”. (Appendix 6).

IV. Consolidation of the studied material.

1. Why do people stop smelling smoke in a smoky room after a while? (The sensitivity threshold decreases).

2. Deaf Beethoven listened to music with a cane, leaning one end against the soundboard of the piano, and taking the other end of the cane in his teeth. Let's do a similar experiment.

Experiment 7. Let's close the subject's ears tightly and put a watch on the top of his head. Do you hear sound? Why? (Sound propagates not only in gaseous media, but also in solids. The ticking clock caused vibrations in the bones of the skull, which led to impulses in the auditory analyzer).

3. Experience 8. Put a cotton swab with vegetable oil in your mouth. Do you smell? What if you didn't breathe in through your nose? (Through the choanae).

4. Suggest an explanation for the phenomenon of Rosa Kuleshova, who, being blind, recognized color, drawings and even font with her hands. (Given the property of specificity, Rose could not see with her hands. Therefore, she received only tactile sensations, which were associated with visual impressions.) Yes, indeed, Rose knew that the color red causes tingling, Brown color she perceived it as viscous, and blue as smooth, cold and slippery. She compensated for her lack of vision by amplifying another analyzer. This is the basis for the training of deaf-blind-mutes according to the method of Meshcheryakov A.Ya. and Sokolyansky I.A.. For training, they used a vibrational sense. To understand what it is, put your hand at home on the body of a sounding receiver and feel the vibrations of the walls. The deaf-blind-mute were taught in a similar way: the student touched the throat or the back of the head of the teacher and felt the vibration when he pronounces sounds, syllables, words and phrases. Then the student placed his hand on his throat and reproduced sounds that caused the same vibrations that he felt from the teacher. These vibrational sensations were associated with the corresponding sounds of the language, which were transmitted using the tactile alphabet. Some of the deaf-blind-mute who were trained according to this method achieved high results. Olga Skorokhodova mastered speech, got an education, defended her doctoral candidate in the field of defectology. So she spoke. But she didn't listen. Formulate a conclusion about compensatory possibilities. Suggested conclusion: due to the interchangeability of analyzers, the weakening of one of them leads to the strengthening of others. Also, thanks to compensatory opportunities, such people become full members of our society.

5. Experiment 9. Touch your nose with two crossed fingers. Are there two? Why? Now look in the mirror at the same time. How many noses? One? Explain. Suggested answer: Feelings in the body are formed as a result of the work of all analyzers and are evaluated by the body in a complex way. In this example, tactile sensations were supplemented by visual sensations, and the sensations were corrected. Thus, the result of the interaction of the analyzers was the correspondence of the sensation to reality.

The results of the lesson are reflection.

And in conclusion, I want to recommend reading the book by Marius Pluzhnikov, Sergey Ryazantsev “Among smells and sounds” © N&T. Rare editions, 1998. The book tells about the physiology of hearing, smell and taste, as well as diseases of the ear, throat and nose. In other words, about all the informative, entertaining, and sometimes curious aspects of otorhinolaryngology. The electronic version of the book can be found at www.n-t.ru/ri/

D / s (optional): make a description of the receptors (any) according to the type of perceived stimuli, the nature of the connection with the stimulus, structural features. (Answer in appendix 8)

Literature:

Anisimova V.S., Brunovt E.P., Rebrova L.V. Independent work students in human anatomy, physiology and hygiene: a guide for the teacher. / M- Education. - 1987.
Voronin L.G., Mash R.D. Methodology for conducting experiments and observations on human anatomy, physiology and hygiene: a book for teachers. / M. - Enlightenment. - 1983.
Demyankov E.N. Biology in questions and answers: A book for teachers./M. - Enlightenment: JSC "Educational Literature" - 1996.
Sementsova V.N. Biology. Technological cards lessons. 8th grade. Methodological guide. / St. Petersburg. - Parity. - 2002.
I'm going to a biology lesson: Man and his health: A book for teachers. / M. - September 1st. - 2000.

Analyzers are a system of sensitive nerve formations that analyze and synthesize changes that occur in the external environment and in the body.

According to I.P. Pavlov, the analyzer consists of three sections: peripheral, that is, perceiving (receptor, or sensory organ), intermediate, or conductive (pathways and intermediate nerve centers), and central, or cortical (nerve cells of the cerebral cortex) . The peripheral section of the analyzers includes everything, as well as receptor formations and free nerve endings located in the internal organs and muscles.

The receptor apparatus of each analyzer is adapted to transform the energy of a certain type of irritation into nervous excitation (see). In the cortical section of the analyzer, nervous excitation turns into sensation. The activity of the cortical department provides adaptive reactions of the body to changes in the external environment.

Analyzers - a system of sensitive (afferent) nerve formations that analyze and synthesize the phenomena of the external and internal environment of the body. The term was introduced into the neurological literature, according to the ideas of which each analyzer consists of specific perceiving formations (see Receptors, Sensory Organs) that make up the peripheral section of the analyzers, the corresponding nerves that connect these receptors with different levels of the central nervous system (conductor part), and the cerebral end, represented by in higher animals in the cerebral cortex.

Depending on the receptor function, analyzers of the external and internal environment are distinguished. The first receptors are turned to the external environment and are adapted to analyze the phenomena occurring in the surrounding world. These analyzers include visual, hearing, skin, olfactory, gustatory (see Vision, Hearing, Touch, Smell, Taste). Analyzers of the internal environment are afferent nervous devices, the receptor apparatuses of which are located in the internal organs and are adapted to analyze what is happening in the body itself. These analyzers also include motor (its receptor apparatus is represented by muscle spindles and Golgi receptors), which provides the ability to accurately control the musculoskeletal system (see Motor reactions). An important role in the mechanisms of statokinetic coordination is also played by another internal analyzer - the vestibular one, which closely interacts with the analyzer of movement (see Body balance). The motor analyzer in humans also includes a special department that ensures the transmission of signals from the receptors of the speech organs to the higher floors of the central nervous system. In connection with important of this department in the activity of the human brain, it is sometimes considered as a “speech-motor analyzer”.

The receptor apparatus of each analyzer is adapted to the transformation of a certain type of energy into nervous excitation. Thus, sound receptors selectively respond to sound stimuli, light to light stimuli, taste to chemical stimuli, skin to tactile-temperature stimuli, etc. The specialization of receptors provides an analysis of the phenomena of the outside world into their individual elements already at the level of the peripheral section of the analyzer.

The most complex and subtle analysis, differentiation and subsequent synthesis of external stimuli are carried out in the cortical sections of the analyzers. The method of conditioned reflexes in combination with the extirpation of the brain tissue has shown that the cortical sections of the analyzers consist of nuclei and scattered elements.

When the nuclei are destroyed, fine analysis is disturbed, but coarse analytic-synthetic activity is still possible due to scattered elements. Such an anatomical and physiological organization ensures the dynamism and high reliability of the functions of the analyzers.

The biological role of analyzers lies in the fact that they are specialized tracking systems that inform the body about all events occurring in the environment and inside it. From the huge stream of signals that continuously enter the brain through external and internal analyzers, is selected helpful information, which turns out to be essential in the processes of self-regulation (maintaining an optimal, constant level of functioning of the organism) and active behavior of animals in the environment. Experiments show that the complex analytical and synthetic activity of the brain, determined by the factors of the external and internal environment, is carried out according to the polyanalyzer principle. This means that the entire complex neurodynamics of cortical processes, which form the integral activity of the brain, is made up of a complex interaction of analyzers (see).

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Human analyzers and their meaning. peripheral - eye

Departments

Kinds

Characteristics

auditory analyzer

Tactile Analyzer

Taste Analyzer

Olfactory analyzer

Human analyzers (sight, hearing, smell, taste, touch)

Functions and types of human analyzers (Table)

Lecture 5. Analyzers

visual analyzer.

Organ of vision.

Pathology of accommodation.

Retina.

auditory analyzer.

Organ of hearing.

vestibular apparatus.

vestibular analyzer.

Human analyzers

Taste analyzer.

Olfactory analyzer.

Tactile analyzer.

2. The concept of anthropogenesis. The main theories of the origin of man. Brief description of cosmism (extraterrestrial origin)

1.3 Brief description of the vegetation of the Mediterranean

1. Brief physical and geographical characteristics

2.1.2 Brief description of clinical signs

1.2 Brief description of the study area

2. Brief description of the class of mammals

4. Brief description of the types of mutations

Basic human analyzers

2.1 Brief description of the classes

2. The main stages of human evolution. Brief description of Australopithecus

I.1.1 Types of analyzers. The structure of the analyzers

2. Brief description of the economy

1. The importance of studying human analyzers from the point of view of modern information technologies

1.1 Structural and functional characteristics, classification and significance of analyzers in the knowledge of the surrounding world

1. Brief description of the noosphere

1.5 Vegetation (brief description).

Analyzers, sense organs and their meaning

human analyzers. The main sense organs and their functions

External analyzers

Human analyzers and their main characteristics.

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