ear lecture Flashcards
What is the path of vibration starting at the stapes?
Vibrations move from the stapes to the oval window to the cochlea as fluid pressure waves and are transmitted into the perilymph of the scala vestibule.
They then travel to the scala tympani and then to the round window which bulges into the middle ear
pressure waves travel from the scala vestibuli to the vestibular membrane to the endolymph of the cochlear duct
the basilar membrane vibrates, which moves the cells of the spiral organ against the tectorial membrane.
the hair cells generate nerve impulses in the cochlear nerve fibers
function of the external auditory meatus?
transmits sound to tympanic membrane
what are the places the nerve impulses from the vestibular nerve travel to?
vestibular nuclei (pons and medulla oblongata), inferior and cerebellar peduncles to cerebellum
function of ceruminous glands?
secrete ear wax
what percentage of people over 60 have hearing loss?
25%
function of pinna?
captures sound
When the stereocilia bend towards the tallest one what happens? What about when it bends the opposite way?
Movement towards the longest stereocilia causes depolarization and excitation. Movement towards the shortest ones causes hyperpolarization and inhibition.
what are the parts of the vestibular apparatus
organs that maintain equilibrium
saccule, utricle, and semicircular canals
function of tympani tensor
supplied by the mandibular branch of the trigeminal (V) nerve, limits movement and increases tension on the eardrum to prevent damage to the inner ear from loud noises
what are the macula receptors for?
static equilibrium
Trace the path of sound starting from outside the ear
- The auricle directs sound waves into the external acoustic meatus.
- When sound waves strike the tympanic membrane, the alternating waves of high and low pressure in the air cause the tympanic membrane to vibrate back and forth. The tympanic membrane vibrates slowly in response to low-frequency (low-pitched) sounds and rapidly in response to high-frequency (high-pitched) sounds.
- The central area of the tympanic membrane connects to the malleus, which vibrates along with the tympanic membrane. This vibration is transmitted from the malleus to the incus and then to the stapes.
- As the stapes moves back and forth, its oval-shaped footplate, which is attached via a ligament to the circumference of the vestibular window, vibrates in the vestibular window. The vibrations at the vestibular window are about 20 times more vigorous than those of the tympanic membrane because the auditory ossicles efficiently transmit small vibrations spread over a large surface area (the tympanic membrane) into larger vibrations at a smaller surface (the vestibular window).
- The movement of the stapes at the vestibular window sets up fluid pressure waves in the perilymph of the cochlea. As the vestibular window bulges inward, it pushes on the perilymph of the scala vestibuli.
- Pressure waves are transmitted from the scala vestibuli to the scala tympani and eventually to the cochlear window, causing it to bulge outward into the middle ear. (See 9 in the figure.)
- As the pressure waves deform the walls of the scala vestibuli and scala tympani, they also push the vestibular membrane back and forth, creating pressure waves in the endolymph inside the cochlear duct.
- The pressure waves in the endolymph cause the basilar membrane to vibrate, which moves the hair cells of the spiral organ against the tectorial membrane. This leads to bending of the stereocilia and ultimately to the generation of nerve impulses in first-order neurons in cochlear nerve fibers.”
what are the semicircular canals responsible for?
dynamic equilibrium
the function of the utricle
detects horizontal linear acceleration and deceleration
the function of semicircular ducts
Detect rotational acceleration or deceleration
What are the parts of the external ear?
pinna, external auditory canal, and tympanic membrane
what are otoliths?
calcium carbonate crystals
what is the function of the eustachian tube?
regulates air pressure in the middle ear
what are the three sections of the ear?
external, middle, inner
What is the pathway for the nerve impulses after they leave the ear?
cochlear nerve->medulla oblongata->medial geniculate nucleus of thalamus->primary auditory area of temporal
also go to inferior colliculi
function of the saccule
detects vertical linear acceleration or deceleration
where is the crista located?
ampula
what are the three auditory ossicles and what is their function?
mallus, incus, stapes
transmit and amplify vibrations from the tympanic membrane to the oval window
what are the functions of the semicircular canals?
balance and equilibrium with cerebellum
Which neurotransmitter is probably released by the bending of the stereocilia?
glutamate
define dynamic equilibrium
the maintenance of the body’s position in response to sudden movements
function of cochlea
Professor said “hearing” is enough but
translates vibrations into neural impulses that the brain can interpret as sound
what is loudness determined by?
intensity of sound waves
Define static equilibrium
maintenance of the body’s position relative to the force of gravity
what in has a high concentration in endolymph?
K+
which frequency of sounds is registered at the base of the cochlea and which at the top?
high frequency at the base
low frequency at the top
