Chapter 15 - Auditory and Equilibrium

Question 1

outer ear is composed of

Answer 1

• pinna/auricle
• external acoustic meatus

Question 2

function of the outer ear

Answer 2

collect sound waves and direct them to eardrum

Question 3

middle ear is composed of

Answer 3

• tympanic membrane
• auditory ossicles: malleus, incus, and stapes
• oval and round windows
• pharyngotympanic tube

Question 4

function of the middle ear

Answer 4

transmit sound waves from outer ear to inner by amplifying sound vibrations through ossicles and adjust pressure difference b/w air and fluid

Question 5

where do infections occur in the ear?

Answer 5

middle ear

Question 6

why do kids get more ear infections than adults?

Answer 6

their pharyngotympanic tube is more horizontal than vertical so fluid gets stuck in ear

Question 7

tensor tympani and stapedius muscles

Answer 7

dampen sound by preventing ossicles from vibrating when there is a loud sound to protect hearing

Question 8

function of pharyngotympanic tube

Answer 8

drains into nasal cavity and it is there to equalize pressure in the middle ear

Question 9

inner ear is composed of

Answer 9

• cochlea
• semicircular canals
• vestibule
• vestibulocochlear nerve
• labyrinths: bony and membranous

Question 10

cochlea

Answer 10

a hearing structure
- consists of 3 membrane-lined chambers
- houses spiral organ of corti

Question 11

semicircular canals

Answer 11

equilibrium structure
- spinning around

Question 12

vestibule

Answer 12

equilibrium structure
- linear balance

Question 13

labyrinth of the inner ear: bony labyrinth

Answer 13

• semicircular canals, cochlea, and vestibule
• filled with perilymph

Question 14

labyrinth of the inner ear: membranous labyrinth

Answer 14

• semicircular ducts, utricle, and saccule and cochlear duct
• filled with endolymph

Question 15

spiral organ of corti

Answer 15

• tectorial memby: upper surface
• basilar memby: bottom border
• contains hair cells

Question 16

hair cells have groups of what? what type of ion channels do they have?

Answer 16

• cilia of different lengths connected by a protein strand called tip link
• mechanically-gated ion channels

Question 17

sound =

Answer 17

vibrations and pressure waves

Question 18

frequency =

Answer 18

pitch

Question 19

amplitude =

Answer 19

loudness

Question 20

pathway of sound waves

Answer 20

1. sound waves vibrate the tympanic membrane
2. vibrates ossicles
3. stapes pushes on oval window which sets the perilymph in cochlea in motion
4. stimulates basilar memby which stimulates hair cells (depends on the frq of sound: middle range stimulates basilar memby, lower pitch doesnt, higher pitch doesnt)
5. vibrations dissipate through round window

Question 21

why does the basilar membrane get “punched” at different locations due to different frqs?

Answer 21

bc of it structure
- Base: very stiff and short fiibers —> medium frqs and high frqs are here
- apex: long floppy fibers –> lower frqs here

Question 22

pathway to brain

Answer 22

1. axons from organ of corti
2. cochlear nerve
3. vestibulocochlear nerve
4. medulla
5. inferior colliculus of midbrain
6. thalamus
7. primary auditory cortex of temporal lobe

Question 23

what are the two different types of equilibrium?

Answer 23

static equilibrium and dynamic equilibrium

Question 24

static equilibrium

Answer 24

aka linear equilibrium
- sensing movement forwards or backwards
- utricle and saccule of vestibule

Question 25

dynamic equilibrium

Answer 25

- rotational movement of head - semicircular canals

Question 26

maculae of utricle and saccule contain what

Answer 26

- hair cells whose cilia project into the otolith membrane - gelatinous substance with otolith crystals

Question 27

static equilibrium at rest

Answer 27

constant act pots sent to the vestibular nerve

Question 28

static equilibrium when head tilts back or forward

Answer 28

otoliths and memby move with tilt

Question 29

head tilted backwards

Answer 29

- hair cells hyperpolarize - decrease in act pots in vestibular nerve

Question 30

head tilted forward

Answer 30

- hair cell depolarizes - nerve fibers excited - inc in act pots in vestibular nerve

Question 31

dynamic movements

Answer 31

when you spin in one direction the flow of endolymph flows in that direction causing ampullary cupula to move to one direction and this causes it to send a certain pattern of act pots and when you spin in the other direction the flow of endolymph changes ---> shifts ampullary cupula to the other side ---> sends different pattern of act pots