hearing and equilibrium

Question 1

what is the function of the ears?

Answer 1

hearing and equilibrium

Question 2

what are the mechanoreceptors and where are they located?

Answer 2

they are the hair cells and are located in fluid-filled membranous/ labyrinth

Question 3

what is the fluid in the membranous?

Answer 3

endolymph- surrounds hair cell
perilymph- circulates around labyrinth

Question 4

what does the outer ear consist of?

Answer 4

auricle
auditory canal
tympanic membrane

Question 5

what does the middle ear consist of?

Answer 5

tympanic cavity
auditory ossicles- malleus, incus, stepes
pharyntympanic or auditory tube

Question 6

what is the auditory tube?

Answer 6

it connects the middle ear to the nasopharynx

Question 7

What does the inner ear consist of?

Answer 7

fluid-filled bony labyrinth lined in the membrane - membranous labyrinth
cochlea, vestibule, semicircular canals

Question 8

what is sound?

Answer 8

air pressure waves
wavelength (distance between waves) pitch of sound
amplitude(height) is the loudness

Question 9

what is frequency?

Answer 9

measured in hz = waves/msec
increased frequency= higher pitch
hertz

Question 10

what is amplitude?

Answer 10

wave height measured in decibals dB
increased amplitude=louder

Question 11

what are the mechanoreceptors?

Answer 11

located in spiral organs (organ of corti) of cochlea
receptors called hair cells

Question 12

what happens when stereocilia on cells bend?

Answer 12

mechanically gated ion channels open and an action potencial occurs

Question 13

explain how the ion channels open for an action potencial to occur?

Answer 13

bending of the stereocillia causes mechanically gated k channels to open, k concentration is high in endolymph so k flows in and depolarization occurs

Question 14

what are the steps in hearing?

Answer 14

1. sound waves cause tympanic m to vibrate
2. ossciles amplify vibrations
3. stapes pushes against oval window creating waves in perilymph
4. pressure waves in tympanic duct moves bassilar m.
5. cilia of hair cells in cochlear duct bend as they touch tectorial membrane causing depolarization
6. wave energy dsicepated at round window

Question 15

what does the flexibility of the basilar membrane varies in length causes what?

Answer 15

causes different hair cells to respond to sounds of different pitch

Question 16

what is equilibrium?

Answer 16

in the inner ear and consists of vestibular aparatus

Question 17

what are the two parts of the vestibular aparatus?

Answer 17

vestibule- utricle and saccule
semicircular canals

Question 18

what are the two types of equilibrium?

Answer 18

static equilibrium from vestibules
head position with respect to gravity and liner acceleration
dynamic equilibrium from semicircular canals
roatational movement of head in space

Question 19

what does reflexive mean?

Answer 19

means we are only aware of it when things go wrong
our maintenance of equilibrium is reflexive

Question 20

what are the sensory receptors involved in equilibrium

Answer 20

hair cells with are mechanoreceptors

Question 21

what is a maculae?

Answer 21

it is in vestibule and is in epithelial patches of walls of utricle and saccule
hair cells have to respond to positional changes in relation to gravity

Question 22

what do the utricle and saccule do in the maculae?

Answer 22

utricle- detects movement in horizontal plane
eg. tilting head linear acceleration
saccule- detects movement in changes vertical plane
eg. being upside down

Question 23

what are the hair cells in macculae embedded in?

Answer 23

jelly-like otolithic membrane which makes it weighted

Question 24

how does equilibrium work in maculae?

Answer 24

crystals of calicium cabronate otoliths add weight to otolithic membrane
membrane slides in the direction of gravity
hair cells stereocilia bend
mechanically gated ion channels open and depolarization occurs

Question 25

what is crista ampulee?

Answer 25

aspect of equilibrium in the semicircular canals

Question 26

where are the hair cells in crista ampulee?

Answer 26

they project into the cupuia which is a hap of gelatinous material

Question 27

describe how crista ampulee works?

Answer 27

roation of head moves the endolymph
capula moves
sterocilia bend
action potencial created

Question 28

what detects rotation?

Answer 28

3 semicircular canals orriented in 3 different planes (ampulla at the base of each canal) detect rotation in different planes

Question 29

what is the sensory pathway for equilibrium?

Answer 29

goes from the vestibular nerve
to vestiocochlear nerve
to vestibular nuclei in medulla oblongata
(motion sickness drugs depress these centers)
can go to either cerebellum or extraocular eye muscles
which sends messages to skeletal position or back to the vestibulocochlear nerve used to stabilize image