Unit 5 Lecture 39

Question 1

What structures make up the external ear?

Answer 1

• Auricle
• External auditory canal
• Eardrum (tympanic membrane)

Question 2

What structures make up the middle ear?

Answer 2

• Auditory tube

- Auditory ossicles

Question 3

What structures makes up the inner ear?

Answer 3

• Semicircular ducts
• Utricle
• Saccule
• Cochlea

Question 4

What are the semicircular ducts responsible for?

Answer 4

equilibrium and balance

Question 5

What is the cochlea responsible for?

Answer 5

Hearing

Question 6

What is the saccule responsible for?

Answer 6

Gravity and acceleration

Question 7

Steps of hearing?

Answer 7

1. Sound waves arrive at tympanic membrane
2. Vibrations moves auditory ossicles
3. Stapes depresses oval window -> generates pressure wave in cochlear ducts
4. Pressure wave distorts basilar membrane (different regions by different wavelengths)
5. Vibration of basilar membrane excites overlaying hair cells (produces receptor potentials)

Question 8

What is paralymph?

Answer 8

Like CSF

Question 9

What is endolymph

Answer 9

extra cellular fluid that’s high in K+

Question 10

Where is endolymph found?

Answer 10

Cochlear duct

Question 11

What is the purpose of hair cells?

Answer 11

They act as receptors for hearing and balance/equilibrium

Question 12

What is the cilia on hair cells called?

Answer 12

stereocilia

Question 13

Define stereocilia

Answer 13

Mechano-sensing organelles on hair cells that move to fluid motion in the ear

(fluid = enyolymph)

Question 14

What type of ion channels are found on stereocilia?

Answer 14

Mechanically gated ion channels

Question 15

Define mechanically gated ion channels

Answer 15

Ion channels that open when the membrane is stretched

Question 16

How is the receptor potential changed in the ear?

Answer 16

• Endolymph hits and MOVES the hairs in the cochlear duct
• Mechanically gated ion channels on the stereocilia OPEN
• K+ in endolymph goes INTO the cell
• DEPOLARIZATION

Question 17

Steps of auditory transduction

Answer 17

1. waves in cochlear
2. moves hairs
3. opens mechanically gated channels on stereocilia
4. K+ into cell -> DEPOLARIZATION
5. Ca+ channels open at base of hair cell
6. Ca+ -> neurotransmitters and depolarization of VIII nerve

Question 18

What causes the most and least damage to hair cells

Answer 18

least = rustling leaves

most = headphones

Question 19

What controls equilibrium and balance?

Answer 19

Semicircular ducts

Question 20

What are the 3 semicircular ducts?

Answer 20

Anterior, posterior and lateral

Question 21

What is found at the base of each duct?

Answer 21

Ampulla

Question 22

What is the ampulla?

Answer 22

the enlargement at the base of each semicircular duct

Question 23

What is found within each ampulla?

Answer 23

Crista

Question 24

What is the crista?

Answer 24

“bundle” of hair cell complexes

Question 25

What is the purpose of the crista?

Answer 25

Senses rotational movements of the head

Question 26

What controls the sense of gravity and acceleration?

Answer 26

Hairs in the UTRICLE and SACCULE

Question 27

What activates the hair cells in the utricle and saccule?

Answer 27

Otoliths

Question 28

What is otoliths?

Answer 28

particles in the fluid found in the utricle and saccule

Question 29

What head movement stimulates the movement of otoliths?

Answer 29

up and down

Question 30

What head movement stimulates the movement of crista?

Answer 30

Side to side