PHYSIOLOGY DEPARTMENT

Ass. Prof. VASTYANOV Rooslan

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SENSORY SYSTEMS #3SENSORY SYSTEMS #3

PHYSIOLOGY OF AUDITORY AND VESTIBULAR SENSORY SYSTEMS

The nature of the sound The nature of the sound

Sound is due to changes in air pressureSound is due to changes in air pressure

Five octaves of a sound Five octaves of a sound

Musical tones can be represented as noteson a staff or as frequency of vibration in Hz Musical tones can be represented as notes

on a staff or as frequency of vibration in Hz

Direct dependence among the sound wavesfrequency pressure and perceived tone

Direct dependence among the sound wavesfrequency pressure and perceived tone

The higher the frequency, the higher the perceived toneThe higher the frequency, the higher the perceived tone

Sound pressure, sound pressure level and loudness level Sound pressure, sound pressure level and loudness level

Outer, middle and internal subdivisions of the ear Outer, middle and internal subdivisions of the ear

Peripheral and conductive parts of the auditory sensory system

Peripheral and conductive parts of the auditory sensory system

The inner and outer hair cells, the basilar membraneand cochlear nerve f ibers

The inner and outer hair cells, the basilar membraneand cochlear nerve fibers

The periotic fluid or perilymphseparates the bony labyrinth

from the membranous labyrinth

The periotic fluid or perilymphseparates the bony labyrinth

from the membranous labyrinth

The otic fluid or endolymphfills the membranous labyrinth

The otic fluid or endolymphfills the membranous labyrinth

Path taken by sound waves reaching the inner ear Path taken by sound waves reaching the inner ear

The scheme of the migrating wave in cochlea The scheme of the migrating wave in cochlea

The scheme showing how the up-and-down movement ofthe basilar and tectorial membrane causes the stereoci- l ia extending from the hair cells to bend back and forth

The scheme showing how the up-and-down movement ofthe basilar and tectorial membrane causes the stereoci- l ia extending from the hair cells to bend back and forth

Frequency-dependent mechanical events in cochlea Frequency-dependent mechanical events in cochlea

The higher the frequency of the sound,the closer the site is to the stapes

The higher the frequency of the sound,the closer the site is to the stapes

Electrical potentials in the cochlea together with electrolyte distribution Electrical potentials in the cochlea

together with electrolyte distribution

There are 5 types of the cochlear AP:

1. The AP of the inner hair cell2. The AP of the outer hair cell3. The microphonic AP4. The AP of the endolymph5. The AP of the cochlear nerve

There are 5 types of the cochlear AP:

1. The AP of the inner hair cell2. The AP of the outer hair cell3. The microphonic AP4. The AP of the endolymph5. The AP of the cochlear nerve

Afferent auditory pathway

Afferent auditory pathway

Thalamus=(MGB) medial

geniculatebody

Areas of the cortex according to Brodmann’s division Areas of the cortex according to Brodmann’s division

The causes of a conductive deafness,air and bone sound conduction

The causes of a conductive deafness,air and bone sound conduction

The causesof a nervedeafness

The causesof a nervedeafness

The vestibular organThe vestibular organ

The vestibular pathways The vestibular pathways

Vestibular organ: effects on postural motor controlVestibular organ: effects on postural motor control

Proprioceptive sensory system

MechanoreceptorsMechanoreceptors

Mechanical sensationMechanical sensationThe pacinian corpuscle is a

very rapidly adapting receptorwith a large receptive field that is used to encode high-frequency

(100–400 Hz) vibratory sensation.

The receptor is located on the end of a group B myelinated fiber, which is inser-

ted into an onion-like lamellar capsule

The pacinian corpuscle is a very rapidly adapting receptor

with a large receptive field that is used to encode high-frequency

(100–400 Hz) vibratory sensation.

The receptor is located on the end of a group B myelinated fiber, which is inser-

ted into an onion-like lamellar capsule

The spindle-shaped Ruffini's corpuscle is a slowly adapting receptor that encodes pressure. It has a large

receptive field that is used to encode the magnitude of a stimulus.

The receptor is located on the terminal of a group B axon that is covered by a liquid-filled collagen capsule. Collagen

strands within the capsule make contact with the nerve fiber and the overlying skin.

The spindle-shaped Ruffini's corpuscle is a slowly adapting receptor that encodes pressure. It has a large

receptive field that is used to encode the magnitude of a stimulus.

The receptor is located on the terminal of a group B axon that is covered by a liquid-filled collagen capsule. Collagen

strands within the capsule make contact with the nerve fiber and the overlying skin.

Meissner's corpuscle is a rapidly adapting receptor that participates

in the touch sensation and low-frequency (10–100 Hz) vibration.

The receptor is located at the end of a

single group B afferent fiber that is inserted into a small capsule.

Meissner's corpuscle is a rapidly adapting receptor that participates

in the touch sensation and low-frequency (10–100 Hz) vibration.

The receptor is located at the end of a

single group B afferent fiber that is inserted into a small capsule.

Merkel’s disk is a slowly adapting receptor with a small receptive field

that is also used to encode the touch sensation.

The epithelial sensory cells form synaptic

connections with branches of a single group B afferent fiber.

Merkel’s disk is a slowly adapting receptor with a small receptive field

that is also used to encode the touch sensation.

The epithelial sensory cells form synaptic

connections with branches of a single group B afferent fiber.

Skin receptors localizationSkin receptors localization