Presentation of the hearing organ and auditory analyzer. Presentation for the lesson "Hearing analyzer. Hearing hygiene" presentation for a biology lesson (8th grade) on the topic. Helmholtz's resonance theory

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Main speech field

• is in the range 200 – 3200 Hz.
• Old people often cannot hear high frequencies.

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• Tones - contain sounds of the same frequency.
• Noises are sounds consisting of unrelated frequencies.
• Timbre is a characteristic of sound determined by the shape of the sound wave.

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Psychological correlates of sound loudness.

• whispered speech – 30 dB
• conversational speech – 40 – 60 dB
• street noise – 70 dB
• scream at the ear – 110 dB
• loud speech – 80 dB
• jet engine – 120 dB
• pain threshold – 130 – 140 dB

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Ear structure

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Outer ear

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• The auricle is a sound catcher, a resonator.
• The eardrum senses sound pressure and transmits it to the bones of the middle ear.

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• It does not have its own period of oscillation, because its fibers have different directions.
• Does not distort the sound. Vibrations of the membrane during very strong sounds are limited by the muscle tensor timpani.

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Middle ear

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The handle of the hammer is woven into the eardrum.

Sequence of information transmission:

• Hammer→
• Anvil→
• Stirrup →
• oval window →
• perilymph → scala vestibular cochlea

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• musculusstapedius. limits stapes vibrations.
• The reflex occurs 10 ms after the impact of strong sounds on the ear.

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The transmission of sound waves in the outer and middle ear occurs in the air.

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• The bone canal is divided by two membranes: a thin vestibular membrane (Reisner)
• and a dense, elastic main membrane.
• At the top of the cochlea, both of these membranes are connected; they have a helicotrema opening.
• 2 membranes divide the bony canal of the cochlea into 3 passages.

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• Stapes
• Round window
• Oval window
• basement membrane
• Three canals of the cochlea
• Reissner's membrane

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Cochlear canals

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1) The superior canal is the scala vestibuli (from the oval window to the apex of the cochlea).

2) The lower channel is the scala tympani (from the round window). The channels communicate, are filled with perilymph and form a single channel.

3) Average or membranous canal filled with ENDOLYMPH.

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Endolymph is formed by a vascular strip on the outer wall of the scala media.

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Domestic

• are arranged in one row,
• there are about 3500 cells.
• They have 30–40 thick and very short hairs (4–5 MK).

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External

• arranged in 3–4 rows,
• there are 12,000 - 20,000 cells.
• They have 65–120 thin and long hairs.

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The hairs of the receptor cells are washed by the endolymph and come into contact with the tectorial membrane.

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Structure of the organ of Corti

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• Internal phonoreceptors
• Tectorial membrane
• External phono receptors
• Nerve fibers
• basement membrane
• Supporting cells

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Excitation of phonoreceptors

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• When exposed to sounds, the main membrane begins to vibrate.
• Receptor cell hairs touch the tectorial membrane
• and become deformed.

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• A receptor potential arises in the phonoreceptors and the auditory nerve is excited according to the scheme of secondary sensory receptors.
• The auditory nerve is formed by processes of neurons of the spiral ganglion.

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Electric potentials of the cochlea

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5 electrical phenomena:

1.phonoreceptor membrane potential. 2.endolymph potential (both are not related to the action of sound);

3.microphone,

4.summation

5. auditory nerve potential (occurs under the influence of sound stimulation).

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Characteristics of cochlear potentials

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1) Membrane potential receptor cell - the potential difference between the inner and outer sides of the membrane. MP= -70 - 80 MV.

2) Endolymph potential or endocochlear potential.

Endolymph has a positive potential in relation to perilymph. This difference is equal to 80mV.

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3) Microphone potential (MP).

• It is recorded when the electrodes are placed on the round window or near the receptors in the scala tympani.
• The MF frequency corresponds to the frequency of sound vibrations arriving at the oval window.
• The amplitude of these potentials is proportional to the intensity of the sound.

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5) Action potential of auditory nerve fibers

It is a consequence of the occurrence of microphone and summation potentials in hair cells. The amount depends on the frequency of the current sound.

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• If sounds up to 1000Hz are effective,
• then APs of the corresponding frequency arise in the auditory nerve.
• At higher frequencies, the frequency of action potentials in the auditory nerve decreases.

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At low frequencies, APs are observed in a large number of nerve fibers, and at high frequencies, in a small number of nerve fibers.

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Block diagram of the auditory system

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Cochlear sensory cells

• Spiral ganglion neurons
• Cochlear nuclei of the medulla oblongata
• Inferior colliculus (midbrain)
• Medial geniculate body of the thalamus (diencephalon)
• Temporal lobe cortex (Brodmann areas 41, 42)

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The role of various parts of the central nervous system

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• Cochlear nuclei are the primary recognition of sound characteristics.
• The lower colliculus provides the primary orientation reflexes to sound.

The auditory cortex provides:

1) reaction to a moving sound;

2) identification of biologically important sounds;

3) reaction to complex sound, speech.

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Theories of perception of sounds of different heights (frequencies)

1. Helmholtz's resonance theory.

2. Rutherford's telephone theory.

3.Theory of spatial coding.

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Helmholtz's resonance theory

Each fiber of the main membrane of the cochlea is tuned to its own sound frequency:

At low frequencies - long fibers at the top;

For high frequencies - short fibers at the base.

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The theory was not confirmed because:

The membrane fibers are not stretched and do not have “resonant” vibration frequencies.

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Rutherford's telephone theory (1880)

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Sound vibrations → oval window → vibration of the perilymph of the scala vestibularis → through the helicotrema vibration of the perilymph of the scala tympani → vibrations of the main membrane

→ stimulation of phonoreceptors

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• The frequencies of action potentials in the auditory nerve correspond to the frequencies of sound acting on the ear.
• However, this is only true up to 1000Hz.
• The nerve cannot reproduce a higher frequency of AP

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Bekesy's spatial coding theory. (Traveling wave theory, place theory)

Explains the perception of sound with frequencies above 1000 Hz

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• When exposed to sound, the stapes continuously transmits vibrations to the perilymph.
• Through the thin vestibular membrane they are transmitted to the endolymph.

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• A “running wave” propagates along the endolymphatic canal to the helicotrema.
• The speed of its spread is gradually decreasing,

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• The amplitude of the wave first increases,
• then declines and weakens
• not reaching the helicotrema.
• Between the point of origin of the wave and the point of its attenuation lies the amplitude maximum.

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Due to the fact that the functional significance of the auricle is small, all its diseases, as well as damage and developmental anomalies, up to complete absence, do not entail significant hearing impairment and are mainly of only cosmetic importance.

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Another thing is external ear canal. Any processes that entail the closure of its lumen thereby lead to disruption of airborne sound transmission, which in turn is accompanied by a significant decrease in hearing.

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A) Atresia of the external auditory canal. Rarely seen. Atresia is complete fusion. Congenital atresia of the external auditory canal usually occurs simultaneously with an anomaly in the development of the auricle, most often with its underdevelopment. Causes of atresia: Chronic diffuse inflammation of the walls of the passage. This inflammation may be primary when inflammatory process occurs as a result of infection from the outside (for example, when scratching or picking in the ear with contaminated objects), or secondary, when inflammation develops as a result of prolonged irritation of the skin of the external auditory canal with pus flowing from the middle ear. The consequence of scarring of the walls of the passage after injury (impact, bruise, gunshot wound) or burn. 2. Pathology of the ear canal

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In all cases, only complete closure of the external auditory canal leads to significant and persistent hearing loss. With incomplete fusions, when there is at least a narrow gap in the ear canal, hearing usually does not suffer; dysfunction in these cases (with incomplete fusions) occurs only as a result of a simultaneously existing pathological process in the middle or inner ear. In the presence of a purulent process in the middle ear, a sharp narrowing of the external auditory canal poses a great danger, since it prevents the outflow of pus from the middle ear and can contribute to the transition purulent inflammation to deeper parts (inner ear, meninges).

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With atresia of the external auditory canal, hearing loss is in the nature of damage to the sound-conducting apparatus, i.e., the perception of low sounds suffers mainly; the perception of high tones is preserved, bone conduction remains normal or even slightly improves. Treatment of atresia of the external auditory canal can only consist of artificial restoration of the lumen through plastic surgery.

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B) Sulfur plug.

When describing diseases of the outer ear, it is necessary to dwell on one pathological process, which, although it does not lead to permanent hearing loss, often causes great concern for the patient himself and his relatives. We are talking about the so-called sulfur plug. Under normal conditions, earwax, mixing with dust particles that enter the external auditory canal from the external air, turns into tiny lumps that are imperceptibly, usually at night when lying on the side, released from the ear or accumulate at the entrance to the external auditory canal and are removed when washing . In some children, this process of self-cleaning the ears from wax is disrupted and wax accumulates in the external auditory canal.

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1) increased function of the sulfur glands (usually as a result of irritation of the skin of the ear canal); 2) narrowness and abnormal curvature of the external auditory canal, making it difficult to remove wax out; 3) Chemical properties sulfur: its increased viscosity, stickiness, which promotes the adhesion of sulfur to the walls of the ear canal. Reasons for the formation of sulfur plugs:

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Gradually accumulating, sulfur forms a plug that fills the lumen of the external auditory canal. The accumulation of sulfur occurs very slowly and is unnoticed by the patient. As long as there is at least a narrow gap between the plug and the wall of the ear canal, hearing is not impaired. However, as soon as a drop of water gets into the ear under these conditions, the wax swells and closes this gap. The complaints of patients in these cases are very typical: suddenly, in the midst of complete well-being, after swimming in the river or washing in a bathhouse, deafness occurred in one, and sometimes in both ears, noise appeared in the ear and in the head, a distorted perception of one’s own voice, which became resonate in the blocked ear and cause an unpleasant sensation.

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The formation of sulfur plugs is often observed in children. Treatment for earwax is very simple: after preliminary softening with special drops, the plug is removed by rinsing the ear warm water from a special syringe. Such washing can only be performed by a doctor or a specially trained paramedic. medical worker(nurse, paramedic). Any attempts self-removal sulfur plugs using all kinds of sticks, spoons, pins, etc. are unacceptable.

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B) Foreign bodies

Foreign bodies in the ear are most often found in children who, out of prank, stick various small objects into the ear: peas, cherry pits, seeds, beads, ears of cereal, etc. In adults who have the habit of scratching and picking in the ear, fragments of a pencil are often found, matches, branches and other items. Sometimes cotton balls are left in the ear and pushed deep into the ear, which some people put in to prevent a cold. In the summer, while sleeping in the open air, small insects sometimes crawl into the ear, which can, with their movements and irritation of the eardrum, cause great concern, and sometimes even severe pain. You should know that the danger is not so much the presence foreign body in the ear, how many unsuccessful attempts to remove it. Under no circumstances should you be tempted by the apparent accessibility of a foreign body and try to remove it with tweezers, a head pin or other improvised objects. All such attempts, as a rule, end in pushing the foreign body deeper and driving it into the bony part of the ear canal, from where the foreign body can only be removed through a rather serious surgical intervention. There are known cases when, during inept attempts to remove a foreign body, it was pushed into the middle ear with rupture of the eardrum, dislocation of the auditory ossicles, and even the development of inflammation of the meninges.

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Pre-medical measures if a foreign body gets into the ear canal

It must be remembered that the presence of a foreign body in the ear, even for several days, cannot cause harm, so a child with a foreign body should be taken to a specialist doctor as soon as possible. Pre-medical measures may consist of the following: 1) killing living foreign bodies by injecting a few drops of some clean substance into the ear liquid oil(warm); 2) for swelling foreign bodies (peas, beans, etc.) - pouring warm alcohol into the ear to cause the foreign body to shrink; 3) for non-swelling bodies (beads, pebbles, cherry pits), as well as living foreign bodies - carefully rinse the ear with warm boiled water from an ordinary rubber syringe. If there is a suspicion of a perforation of the eardrum, lavage is not performed.

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Isolated diseases, damage and anomalies in the development of the eardrum are rare. Congenital underdevelopment or absence of the eardrum usually accompanies congenital atresia of the external auditory canal. In these cases, the tympanic cavity, auditory ossicles, muscles of the middle ear, etc. are also underdeveloped. 3. Diseases of the eardrum

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Perforation is a violation of its integrity, which occurs as a result of mechanical stress, pressure differences inside and outside the tympanic cavity, and an inflammatory process. Damage to the eardrum, accompanied by its perforation, is observed when picking in the ear with hairpins, matches and other objects, as well as during inept attempts to remove a foreign body from the external auditory canal. Ruptures of the eardrum often occur during rapid fluctuations in atmospheric pressure. IN war time ruptures of the eardrum most often occur during air contusion as a result of loud sounds from explosions of artillery shells, aerial bombs, mines, hand grenades, as well as shots fired near the ear.

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Violation of the integrity of the eardrum, while the remaining parts of the auditory organ are intact, has a relatively small effect on auditory function (in this case, only the transmission of low sounds suffers). The main danger in case of perforations and ruptures of the eardrum is the possibility of infection entering the tympanic cavity with the subsequent development of purulent inflammation of the middle ear. Therefore, in case of ear injuries accompanied by a rupture of the eardrum, the ear cannot be washed; it should be covered with sterile cotton wool.

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Inflammatory diseases eardrums in isolated form are almost never observed. Most often they occur as secondary changes in inflammatory processes in the middle ear.

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Middle ear diseases

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Middle ear diseases are considered very common in all age groups, especially in childhood. With an unfavorable course, these diseases often lead to persistent hearing loss, sometimes reaching a sharp degree. Due to the anatomical and physiological connection of the middle ear with the inner ear and its topographic proximity to the meninges, inflammatory processes in the middle ear can cause serious complications in the form of diseases of the inner ear, meninges and the brain itself.

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There are two main forms of inflammatory processes in the middle ear - catarrhal and purulent.

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Inflammatory processes in the nasopharynx that occur with a runny nose, flu, sore throat and other diseases can spread to the auditory tube and cause closure of its lumen due to inflammatory swelling of the mucous membrane. Closure of the lumen of the auditory tube can also occur with adenoid growths in the nasopharynx. Blockage of the auditory tube leads to the cessation of air flow into the tympanic cavity. The air in the middle ear is partially absorbed by the mucous membrane (due to the absorption of oxygen by capillary vessels), so that the pressure in the tympanic cavity decreases, and the eardrum, due to the predominance of external pressure, is drawn inward. Rarefaction of the air in the tympanic cavity leads, in addition, to the sweating of blood plasma from the vessels of the mucous membrane and to the accumulation of this fluid in the tympanic cavity (secretory otitis media). This liquid sometimes becomes viscous due to the formation of large quantity protein, or becomes hemorrhagic in nature. Therefore, chronic catarrhal inflammation of the middle ear is described under the names mucosal otitis, “sticky” ear, “blue” ear.

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Connective tissue bridges sometimes form between the eardrum and the walls of the tympanic cavity. As a result of impaired mobility of the eardrum, hearing loss occurs and noise in the ear appears. Acute middle ear catarrh in the absence of timely and proper treatment can go to chronic form. Chronic catarrhal inflammation of the middle ear can develop without a previous acute one, namely with chronic inflammatory processes in the nasopharynx and adenoids. In these cases, the process in the middle ear develops slowly, gradually and becomes noticeable to the patient and others only when the hearing loss reaches a significant degree. Sometimes patients note some improvement in hearing, usually in dry weather, and, conversely, worsening hearing in damp weather and during a runny nose.

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Catarrhal inflammation of the middle ear is especially often observed in children of preschool and primary school age as one of the main causes of persistent hearing impairment that occurs at this age. The main role in its occurrence in children is played by adenoid growths in the nasopharynx.

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Treatment is reduced to restoring the patency of the auditory tube. To do this, first of all, it is necessary to eliminate the reasons that caused its closure. The nose and nasopharynx are treated; if adenoid growths are present, they are removed. In some cases, these measures already lead to improved patency eustachian tube and to restore or improve hearing; but often, especially with prolonged catarrhs, one has to resort to special treatment ear - blowing, massage, physiotherapeutic procedures. Blowing out the ear is done using a special rubber balloon. Air is blown into the auditory tube through the corresponding half of the nasal cavity. Blowing helps restore the patency of the auditory tube and leads to equalization of pressure in the middle ear.

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Sometimes parents and educators are afraid that their child’s hearing will deteriorate as a result of blowing out the ears. This fear is unfounded, since blowing the ear, carried out in the presence of appropriate indications, not only does not worsen hearing, but, on the contrary, leads to improvement or restoration of hearing, although sometimes not immediately after the first blow, but only after several such procedures. In some cases (in the presence of persistent retraction of the eardrum), in addition to blowing, a pneumatic massage of the eardrum is performed: using a special device, a rarefaction and condensation of air is caused in the external auditory canal, as a result of which the mobility of the eardrum is restored. Pneumatic massage of the right eardrum with a pneumatic funnel Siegle APMU - “Compressor”. Apparatus for pneumomassage of the eardrum

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To accelerate the resorption of inflammatory swelling of the mucous membrane of the auditory tube, various physiotherapeutic procedures are used. In cases of persistent process, in the absence of effect conservative treatment, and also if the function of the auditory tube is not restored after adenoma, operations are currently performed. The eardrum is cut and a shunt is inserted into the hole. There is a possibility of outflow from the tympanic cavity and impact on its mucous membrane by administering drugs. In 2-3 months. The shunt is removed and the hole closes on its own.

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Acute purulent inflammation of the middle ear (acute purulent otitis media).

Acute inflammation of the middle ear occurs mainly due to the transfer of infection from the nose and nasopharynx through the auditory tube into the tympanic cavity. Most often, acute otitis media develops in acute infectious diseases - influenza, sore throat, measles, scarlet fever, etc. More rare ways of introducing infection into the middle ear are the penetration of microbes from the outer ear through a damaged eardrum and the introduction of pathogens from other organs through the blood vessels.

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Symptoms of acute inflammation of the middle ear are pain in the ear, decreased hearing; usually elevated temperature. Ear pain can be very sharp and sometimes becomes unbearable. It is explained by the accumulation of inflammatory fluid in the tympanic cavity and its pressure on the eardrum, which is very sensitive. The inflammatory process usually also involves the eardrum, its tissues loosen, and under the influence of pus pressure, the eardrum perforates. After a breakthrough, the fluid accumulated in the tympanic cavity receives a free outflow, and in connection with this, pain in the ear usually immediately subsides, and the temperature drops.

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Sometimes, when mild degree inflammation, recovery occurs even without perforation of the eardrum. In these cases, the inflammatory fluid is partially absorbed by the mucous membrane of the tympanic cavity, and partially poured through the auditory tube into the nasopharynx. If spontaneous perforation of the eardrum does not occur, and the patient’s condition does not improve, the pain in the ear does not subside or even increases, the temperature does not decrease, then the doctor makes an incision of the eardrum (paracentesis), after which discharge from the ear usually immediately appears and the patient’s condition quickly is improving.

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Discharge from the ear is initially liquid, sanguineous, then becomes mucous, stretches out in the form of threads when rubbing the ear, then acquires a purulent character and becomes thick, sometimes creamy. Pus in acute otitis media has no odor. With modern treatment methods, acute inflammation of the middle ear is most often cured. The duration of the disease usually does not exceed three to four weeks. The amount of discharge gradually decreases, then the suppuration stops, the hole in the eardrum closes with a gentle scar, and hearing is restored.

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Spicy otitis media in children it is observed much more often than in adults, since it quite often complicates all children’s infectious diseases(measles, scarlet fever, whooping cough, mumps, rubella, etc.). Middle ear disease in infants is facilitated by constant lying on the back, which facilitates the flow of mucus and pus from the nose into the nasopharynx, as well as the presence of a short and wide auditory tube. IN infancy Otitis occurs most often with influenza, while other infections are complicated by otitis, usually in preschool and early school age. In preschoolers and primary schoolchildren, the development of inflammation of the middle ear is often facilitated by adenoid growths in the nasopharynx.

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In infants, acute otitis may go unnoticed by others until a leak appears from the sore ear. However, if you carefully observe the child's behavior, you will notice some characteristic features diseases: the child becomes restless, sleeps poorly, cries out during sleep, turns his head, sometimes grabs his hands sore ear. Due to increased pain in the ear when swallowing and sucking, the child stops sucking or refuses the breast and pacifier. It is sometimes noted that the child is more willing to suckle at a breast that corresponds to his healthy ear (for example, with right-sided otitis - left breast): apparently, when lying on the side of the sore ear, sucking and swallowing are less painful.

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Fever in children, especially early age, often very high - reaches 40° and above. Often, children with acute otitis media experience symptoms of irritation of the meninges - vomiting, convulsions, tilting of the head. After perforation of the eardrum or paracentesis, these phenomena usually disappear. Acute inflammation of the middle ear - otitis media (from the Greek otos - ear) is a very serious illness, therefore, at the very first symptoms, you must contact an ear specialist and strictly follow the doctor’s instructions about the regimen and treatment.

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Chronic purulent inflammation of the middle ear (chronic otitis media). Acute inflammation of the middle ear in most cases ends, as already mentioned, within 3-4 weeks with recovery. However, often under unfavorable conditions, acute otitis media takes a protracted course and becomes chronic: the perforation of the eardrum remains persistent, the inflammatory process in the middle ear does not end, suppuration from the ear sometimes continues continuously for many years or periodically renews, hearing remains reduced and even gradually getting worse. The transition of acute otitis to the chronic form is facilitated by the severity of the infection and weakened general state body. Diseases of the nose and nasopharynx play a major role in maintaining the inflammatory process in the middle ear: chronic runny nose, polyps, adenoid growths, etc.

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There are two forms of chronic suppurative otitis media. In the first form (mesotympanitis), the inflammatory process is limited only to the mucous membrane of the middle ear, without spreading to the bone walls of the tympanic cavity. This form is characterized by a benign course and, as a rule, does not cause complications. Pus in benign otitis usually has no odor, and if a foul odor appears, it is only due to poor care, when the pus lingers in the ear and mixes with rejected elements skin and undergoes putrefactive decomposition. In the second form (epitympanitis), the inflammatory process spreads to the bone walls of the tympanic cavity, causing the so-called caries, i.e. necrosis (death) bone tissue, proliferation of granulation and polyps and is accompanied by the release of pus with a pungent putrefactive odor.

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With careful care and careful treatment, chronic purulent otitis media can result in recovery. However, only in a very limited number of cases is it possible to achieve real recovery, that is, healing of the eardrum and restoration of hearing. In most cases, recovery is relative: suppuration stops, but the perforation of the eardrum remains. Scars often form in the tympanic cavity, which limit the mobility of the auditory ossicles. In this case, hearing not only does not improve, but sometimes even worsens. Despite the relativity of such recovery, it is still a favorable outcome of chronic purulent otitis, since the elimination purulent focus in the ear protects the patient from dangerous complications.

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It is necessary, however, to remember that the presence of a perforation of the eardrum poses a constant threat of a new outbreak of inflammation due to the possibility of new penetration of infection through the external auditory canal. A particular danger is when contaminated water gets into the middle ear; Therefore, all patients with a perforated eardrum should be warned about the need to plug their ears with cotton wool, lubricated or soaked in some kind of fat (vaseline, petroleum jelly or other liquid oil) when washing their hair and when bathing. Earplugs

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Inner ear diseases

Isolated diseases of the labyrinthine fluid or the main membrane almost never occur, and are usually accompanied by disruption of the functions of the organ of Corti; therefore, almost all diseases of the inner ear can be attributed to damage to the sound-receiving apparatus. Wardenburg syndrome The most common are a wide protruding bridge of the nose (75%), fused eyebrows (50%), heterochromia of the irises (45%), sensorineural deafness due to hypoplasia of the organ of Corti (20%), white strands of hair above the forehead (17-45%), areas of depigmentation on the skin and fundus.

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Defects and damage to the inner ear.

To the number birth defects include developmental abnormalities of the inner ear, for example, complete absence labyrinth or underdevelopment of its individual parts. In most congenital defects of the inner ear, underdevelopment of the organ of Corti is noted, and it is the specific terminal apparatus of the auditory nerve - the hair cells - that is undeveloped. In these cases, in place of the organ of Corti, a tubercle is formed, consisting of nonspecific epithelial cells, and sometimes this tubercle does not exist and the main membrane turns out to be completely smooth. In some cases, underdevelopment of hair cells is observed only in certain areas of the organ of Corti, and throughout the rest of the area it suffers relatively little. In such cases, the auditory function in the form of hearing islands may be partially preserved. Usher syndrome - congenital sensorineural deafness and retinitis pigmentosa - a combination of congenital sensorineural hearing loss, slowly progressive pigmentary degeneration retina (beginning in the first or second decade of life) and vestibular disorders. Additional signs: glaucoma, cataracts, nystagmus, macular degeneration, mental retardation, psychoses.

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Causes of congenital pathologies

In the occurrence of congenital defects in the development of the auditory organ, all kinds of factors that disrupt the normal course of development of the embryo are important. These factors include pathological effects on the fetus from the mother’s body (intoxication, infection, injury to the fetus). Hereditary predisposition may also play a role.

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Inner ear damage

occur during labor, for example, as a result of compression of the fetal head by narrow birth canal or a consequence of the application of obstetric forceps during pathological childbirth. sometimes observed in young children with head injuries (fall from height); in this case, hemorrhages into the labyrinth and displacement of individual sections of its contents are observed. Sometimes in these cases, both the middle ear and the auditory nerve can be damaged at the same time. The degree of impairment of hearing function due to injuries of the inner ear depends on the extent of the damage and can vary from partial hearing loss in one ear to complete bilateral deafness.

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Inflammation of the inner ear (labyrinthitis)

occurs in three ways: due to the transition of the inflammatory process from the middle ear; due to the spread of inflammation from the meninges due to the introduction of infection through the bloodstream (in general infectious diseases).

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1 reason

With purulent inflammation of the middle ear, the infection can enter the inner ear through the round or oval window as a result of damage to their membranous formations (secondary tympanic membrane or annular ligament). For chronic purulent otitis the infection can spread to the inner ear through the bone wall destroyed by the inflammatory process, separating the tympanic cavity from the labyrinth.

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Reason 2

From the side of the meninges, the infection enters the labyrinth usually through the internal auditory canal along the auditory nerve sheaths. This kind of labyrinthitis is called meningogenic and is most often observed in early childhood with epidemic cerebrospinal meningitis (purulent inflammation of the meninges). It is necessary to distinguish cerebrospinal meningitis from meningitis of ear origin, or so-called otogenic meningitis. The first one is spicy infectious disease and gives frequent complications in the form of damage to the inner ear, and the second itself is a complication of purulent inflammation of the middle or inner ear.

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According to the degree of prevalence of the inflammatory process, diffuse (spread) and limited labyrinthitis are distinguished. As a result of diffuse purulent labyrinthicorti organ, the organ dies and the cochlea is filled with fibrous connective tissue. With limited labyrinthitis, the purulent process does not involve the entire cochlea, but only part of it, sometimes only one curl or even part of a curl. Diffuse purulent labyrinthitis leads to complete deafness; The result of limited labyrinthitis is partial hearing loss for certain tones, depending on the location of the lesion in the cochlea. Since the dead nerve cells of the organ of Corti are not restored, deafness, complete or partial, that occurs after purulent labyrinthitis is persistent.

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In cases where the vestibular part of the inner ear is also involved in the inflammatory process during labyrinthitis, in addition to impaired auditory function, symptoms of damage to the vestibular apparatus are also noted: dizziness, nausea, vomiting, loss of balance. These phenomena gradually subside. For serous labyrinthitis vestibular function to one degree or another, it is restored, and in case of purulence, as a result of the death of receptor cells, the function of the vestibular analyzer completely disappears, and therefore the patient is left with uncertainty in walking for a long time or forever, and a slight imbalance.

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Diseases of the auditory nerve, pathways and auditory centers in the brain

Lesions to the conductive section of the auditory analyzer can occur on any segment of it. The most common are diseases of the first neuron, united in a group called auditory neuritis. This name is somewhat conditional, since this group includes not only diseases of the auditory nerve trunk, but also lesions of the nerve cells that make up the spiral ganglion, as well as some pathological processes in the cells of the organ of Corti

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The bipolar nerve cells of the spiral ganglion are very sensitive to all kinds of harmful influences. They are easily subject to degeneration (degeneration) when exposed to chemical poisons, in particular when intoxicated with certain medicinal substances, household and industrial poisons (quinine, streptomycin, salicylic drugs, arsenic, lead, mercury, nicotine, alcohol, carbon monoxide, etc.). Some of these substances (quinine and arsenic) have a special affinity for the nervous elements of the auditory organ and act selectively on these elements, just as, for example, methyl alcohol (wood alcohol) acts selectively on nerve endings in the eye and causes blindness due to the onset of optic nerve atrophy. Intoxication of cells and the spiral nerve ganglion occurs not only when poisoned by chemical poisons, but also by exposure to bacterial poisons (toxins) circulating in the blood during many diseases, such as meningitis, scarlet fever, influenza, typhoid, mumps, etc. As a result of intoxication with both chemical poisons, and bacterial ones, the death of all or part of the cells of the spiral ganglion occurs, followed by complete or partial loss of auditory function.

Slide 51

The nature of the hearing impairment depends on the location of the lesion. In cases where the process develops in one half of the brain and involves the auditory pathways up to their intersection, hearing in the corresponding ear is impaired; if all the auditory fibers die, then a complete loss of hearing occurs in this ear; if the auditory pathways are partially destroyed, a greater or lesser decrease in hearing occurs, but again only in the corresponding ear. With unilateral lesions of the pathways above the intersection, bilateral hearing loss occurs, more pronounced on the side opposite to the lesion; Complete hearing loss, even in one ear, does not occur in these cases, since impulses from both receptors will be conducted to the central end of the analyzer along the preserved pathways of the opposite side.

Slide 52

Diseases of the auditory cortex

Causes: hemorrhages, tumors, encephalitis. Unilateral lesions lead to decreased hearing in both ears, more so in the opposite ear. Bilateral lesions of the pathways and the central end of the auditory analyzer are rare. And if they do occur, it is usually only with extensive brain damage and is accompanied by such profound disturbances of other brain functions that the hearing loss itself is big picture defeats are relegated to the background.

Slide 53

Hysterical deafness

developing in people with a weak nervous system under the influence of strong stimuli (fear, fear). Cases of hysterical deafness are sometimes observed in children. surdomutism – occurs after a concussion, accompanied by speech impairment.

Slide 54

Classification of permanent hearing impairment

Slide 55

Medical and pedagogical classification of hearing loss (B.S. Preobrazhensky)

Slide 56

Conclusion

In the matter of prevention and correct, timely treatment ear diseases For children, the role of teacher and educator is great. Teachers and educators must have the necessary knowledge about the manifestations of the most important ear diseases and the possibilities that medicine has for their treatment. The teacher needs this knowledge to promptly refer the child to a specialist; to promote the dissemination of correct views on the treatment of deafness and hearing loss; assist a medical specialist in carrying out therapeutic and preventive measures.

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Biology Presentation - Hearing analyzer

Hearing analyzer- a set of structures that ensure the perception of sound information, convert it into nerve impulses, and its subsequent transmission and processing in the central nervous system.

Structure of the hearing aid
The organ of hearing and balance in mammals and humans consists of:
Outer and middle ear (conducting sound)
Inner ear (receiving sound)

Inner ear (snail)
The inner ear is a bony labyrinth (cochlea and semicircular canals), within which lies,
repeating its shape, a membranous labyrinth. The membranous labyrinth is filled with endolymph, the space between the membranous and bony labyrinth is filled with perilymph (perilymphatic space). Normally, a constant volume and electrolyte composition (potassium, sodium, chlorine, etc.) of each liquid is maintained

Organ of Corti
The organ of Corti is the receptor part of the auditory analyzer, which converts the energy of sound vibrations into nervous stimulation. The organ of Corti is located on the basilar membrane in the cochlear canal of the inner ear, filled with endolymph. The organ of Corti consists of a number of internal and three rows of external sound-perceiving hair cells, from which fibers of the auditory nerve extend.

Vestibular apparatus
The vestibular apparatus is an organ that perceives changes in the position of the head and body in space and the direction of body movement in vertebrates and humans; part of the inner ear. The vestibular apparatus is a complex receptor of the vestibular analyzer. The structural basis of the vestibular apparatus is a complex of clusters of ciliated cells
inner ear, endolymph, calcareous formations included in it - otoliths and jelly-like cupules in the ampoules of the semicircular canals.

Ear diseases
Cold wind or frost, injury, boil, inflammation, accumulation of sulfur and much more can cause pulling or cutting pain in the ear and lead to the formation of an abscess. The most common cause of deafness is a buildup of earwax. Chronic illness ear canal, infections can cause swelling and hearing loss. The cause of hearing loss is mechanical trauma to the eardrum and scars on it. In older people, the tiny bones behind the eardrum often become fused and cause them to go deaf. Hearing is worsened by obesity, kidney disease, nicotine abuse, allergies, large doses of aspirin, antibiotics, diuretics, heart medications, tonic. A severe runny nose worsens hearing for several days.

Ear hygiene
Nature surprisingly provided for periodic cleaning of the ear by moving wax. The condition of the ear, surprisingly, affects overall health. For example, due to increased pressure of sulfur on the eardrum, dizziness may occur. It is best to knead the outer ear (pinna) with your hand, rotating it in all directions, pulling it down and forward, forcing the earwax and its remains to move and come out. The ear canal needs no less attention and care. In a healthy ear, wax does not collect. Local ear pain, itching, irritation or inflammation of the canal can not only be easily prevented, but even cured by a little daily care of this organ. Ear drops soften sulfur, can increase its mass and increase pressure without bringing any benefit. Daily cleaning of the auricle consists of irrigating the openings and washing the outer parts with ordinary water. The index finger needs to be inserted into the ear and with a slow movement from side to side with light pressure on the wall, remove wax, dry dead cells and dust accumulated during the day.

Download Biology Presentation - Hearing Analyzer

Publication date: 11/09/2010 05:12 UTC

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The purpose of the lesson: to form in students knowledge about the importance of hearing in human life on the basis of interdisciplinary integration.

Lesson objectives:

Educational:

continue to develop knowledge about the structure of analyzers using the example of an auditory analyzer;

consider the structure and functions of the ear;

study how sound energy is converted into mechanical energy;

develop rules of hearing hygiene.

Developmental:

develop the ability to compare, analyze, formulate conclusions, work independently with information sources, apply acquired knowledge to solve practical problems;

promote the development of the ability to integrate material from different sciences (biology, physics, history, music, literature).

Educational:

cultivate a sense of responsibility, mutual assistance, and communication skills;

continue to develop skills and abilities careful attitude to your health.

Lesson type: combined.

Equipment: multimedia projector, computer, thinking sheet, didactic material(biological lotto - cards with a matching task), cotton swabs.

During the classes

1. Organizational moment. Psychological mood for the lesson.

Hello guys. I will now ask everyone who came to school today in a good mood to smile. Now raise your hands, those guys who were in a hurry to get to school. Those guys who will help me in class today, clap your hands. I am also glad to meet you.

2. Updating knowledge and skills.

Today you will work not only with the textbook and presentation fragments, but also with thinking sheets (appendix 2) that you see on your table.

Tell me which departments nervous system are we studying with you?

That's right, analyzers.

Why are analyzers needed?

Yes, to live in the world, to feel it, to experience it. Any analyzer has its own components, name them.

(Slide 2).Task No. 1. Break into groups. On the slide you see the analyzer's departments. On the thinking sheet ( appendix 2 ) – departments of different analyzers. Break into groups.

Let's look at slide 3 and compare with the correct answer.

Task No. 2. Remind me which analyzer we talked about in the last lesson.

That's right, about the visual.

Each of you has a biological lotto on the table; after working in pairs, connect the cards according to their meaning.

Let's check if we did it correctly ( slide 4).

Look at ( slide 5). What is he talking about?

That's right, about color blindness - a disease in which a person cannot distinguish certain colors.

(Slide 6). The disease was named after the scientist Dalton, who suffered from this disease.

3. Studying new material.

Now look at the epigraph of our lesson, which is placed on the board. Let's read it out loud:

The world of sounds is so diverse,
Rich, beautiful, diverse,
But we are all tormented by the question:
Where do sounds come from?
Why do our ears delight everywhere?
It's time to think seriously.

So, what is the topic of our lesson?

Hearing analyzer.

And what is sound after reading Zabolotsky’s poem on a thinking sheet ( appendix 2 ), you will understand what it is.

Born of the desert, the sound fluctuates,
A blue spider sways on a thread.
The air vibrates
Transparent and clean
In the shining stars
The leaf sways.

(N. Zabolotsky)

Let's turn to physics. The fact is that sound is mechanical vibrations, occurring with a frequency of 20 to 20,000 Hz i.e. from 20 to 20,000 times per second. Talking about the structure human body, we must not forget that we study ourselves in order to maintain health.

4. Physical education break.

While working in class, we strain our eyes, so it is very important to do eye exercises. We rotate our eyes, draw an infinity sign with our eyes, look intently at the tip of the finger, bringing it closer and further away.

5. Continue learning new material.

Now we will talk about the structure of the auditory analyzer.

Receptors – auditory nerve – temporal zone of the cerebral cortex.

We study the structure of the ear. ( slide7): Organ of hearing - ear: external, middle, internal.

Work through the textbook (pp. 85-87). Fill out the diagram ( appendix 2 ):

Let's look at the board where the correctly completed diagram is placed; I suggest comparing and correcting errors if you have any.

(Slide 8.9) . Now let's talk about the functions:

Auricle: picks up sounds

External auditory canal: conducts sound vibrations

Eardrum: converts sound vibrations into mechanical vibrations and transmits them to the middle ear.

Auditory ossicles: the hammer and anvil are levers, the stirrup is a kind of piston. They amplify weak vibrations of the eardrum and transmit them to the inner ear. The stapes rests against the oval window.

Eustachian tube: connects the middle ear to the nasopharynx. Equalizes the pressure that occurs during increased noise. (ear, nose and throat doctor).

Snail: 2.5 turn sink. Inside the bony labyrinth of the cochlea is the membranous labyrinth. Both of them are filled with liquid, the vibrations of which are caused by impacts of the stapes on the oval window. Inside the membranous labyrinth, along the entire length of the cochlea's curls, there are five rows of cells with the finest fibers (60-70 for each cell). These auditory hair cells (there are about 24 thousand of them) are attached to a membrane, which consists of individual fibers. As soon as vibrations occur in the cochlear fluid, the curtain begins to touch the hairs of the auditory cells, giving rise to electrical impulses of varying strength. The auditory nerve collects these impulses and transmits them through the subcortical ganglia to the cortex of the temporal lobes of the brain. They provide analysis and synthesis of sounds.