The Ear

Question 1

what are the components of the outer ear ?

Answer 1

Auricle, Auditory canal, & Tympanic membrane (ear drum)

Question 2

what are the components of the middle ear ?

Answer 2

tympanic cavity, Eustachian tube, oval&round window

Question 3

osseous labyrinth ?

Answer 3

Bony chamber in temporal bone

Comprised of vestibule, semicircular canals and the scala tympani and scala vestibuli of the cochlea

Question 4

where can endolymph and perilymph be found ?

Answer 4

The membranous labyrinth is filled with endolymph

The bony labyrinth is filled with perilymph

Question 5

difference b/w membranous and bony labyrinth ion concentrations

Answer 5

membranous: High K+, low Na+
bony: High Na+, low K+.

Question 6

Ménière’s Disease

Answer 6

Increase in volume of endolymph
Cause unknown
Typically involves one ear only
Symptoms include episodic attacks of
Vertigo, Nausea & vomiting, Nystagmus, Tinnitus

Question 7

nystagmus

Answer 7

is a vision condition in which the eyes make repetitive, uncontrolled movements

Question 8

Perilymphatic duct connects with the ??

Answer 8

Perilymphatic duct connects with the subarachnoid space

Question 9

Membranous labyrinth?

Answer 9

Within chambers of osseus labyrinth

Comprised of the semicircular ducts, cochlear duct (scala media), saccule and utricle

Question 10

in membranous labyrinth ) Endolymph formed in ____? and Endolymph is absorbed in the ____?

Answer 10

stria vascularis

endolymphatic sac

Question 11

modiolus ?

Answer 11

Modiolus – bone in center of cochlea, around which the scalae wrap.

Question 12

what are found within the modiolus ?

Answer 12

The spiral ganglion (containing bipolar sensory nerves) and nerve fibers of the cochlear nerve are found within the modiolus

Question 13

stria vascularis is made up of ehat kind of epithelium

Answer 13

psedodtraified columnar

Question 14

what separates scala media from scala vestibuli ?

Answer 14

vestibular membrane - “roof”

Question 15

what separates the scala media from scala tympani?

Answer 15

basilar membrane: floor

Question 16

oval window lies next to the scala __?

Answer 16

vestibuli

Question 17

round window lies next to scala __?

Answer 17

tympani

Question 18

sound travels from _ window to __ window

Answer 18

oval to round

Question 19

function of stria vascularis

Answer 19

Secretes endolymph
Proper function essential for normal hearing
Contains a few melanocytes, also needed for normal hearing

Question 20

At the base of the cochlea, the basilar membrane resonates best to

Answer 20

high frequencies

Question 21

At the apex of the cochlea, the basilar membrane resonates best to

Answer 21

low frequencies

Question 22

helicotrema ?

Answer 22

apex of the cochlea

Question 23

hair cells in the cochlea have sterocilia but no __?

Answer 23

kinocilium

Question 24

sterocilia vs kinocilium ?

Answer 24

sterocilia- long microvilli

kinocilium- cilium with axonemre

Question 25

path of sound in cochlea hair cells ?

Answer 25

sound , stereocilia bend, sterocilia stretch tip links,
A calcium channel is mechanically opened by increased tension on the tip links.

Calcium & potassium enter the cell.

The calcium triggers the release of the neurotransmitter glutamate.

Excess glutamate release (e.g. from excessive exposure to noise) can be “excitotoxic” and damage hair cells

Question 26

supporting cells of cochlea

Answer 26

pillar

inner and outer phalangeal cells

Question 27

Mutations in some __ and__can cause deafness

Answer 27

myosins and connexins

Question 28

cupula

Answer 28

gelatinous substance that hair cells and kinocilium project into (in semicirular duct )

Question 29

what causes bending of the stereocilia and the kinocilium?

Answer 29

sloshing of endolymph; rotating head

Question 30

what depolarizes the hair cell in semicircular ducts ?

Answer 30

moverment of sterocilia towards the kinocilium

Question 31

what hyperpolarizes the hair cell in semicircular ducts ?

Answer 31

movement od sterocilia AWAY from thr kinocilium

Question 32

The macula of the inner ear senses ___?

Answer 32

linear acceleration of the head

Question 33

Inertia of the otoliths causes __??

Answer 33

otolithic membrane to lag behind, bending the stereocilia