Chapter 10 Pt. 3 (Part 2)

Question 1

what structures in the middle ear are responsible for sound amplification?

Answer 1

• tympanic membrane
• 3 ear bones
• oval window

Question 2

what is the function of the Eustachian tube?

Answer 2

links middle ear to the back of the nose, when open, it equalizes pressure between the middle ear and outside

Question 3

what is the clinical complication associated with the Eustachian tube? (2) how is it treated? (1)

Answer 3

bacterial infection

often poorly developed in children and doesn’t drain properly

treated with air tubes

Question 4

what inner ear structure converts sound waves into APs?

Answer 4

cochlea

Question 5

what is the function of the function of the function of the function of the round window on the cochlea?

Answer 5

1. allows fluid movement, but
2. avoid pressure build-up in cochlea, so pressure is relieved by outward displacement of the round window

Question 6

how does the cochlea differentiate between different pitches?

Answer 6

higher frequency is closer to the oval window, lower frequency is farther into the cochlea

Question 7

how does the cochlea differentiate between different loudness-es?

Answer 7

louder noises bend the hair cells more!

Question 8

how is sound, a mechanical stimulus, converted into an electrical signal?

Answer 8

1. sound bends inner cochlear membranes
2. bend stereocilia on hair cells
3. some hair cells depolarize, other hyperpolarize; amount of NT released from each hair cell depends on the depolarization
4. each hair cell synapses with an afferent neuron
5. afferent neurons are bundled together to make
6. the cochlear nerve
7. cochlear afferent neurons synapse with ITNs in the medulla oblongata
8. ITNs from medulla synapse with third order ITNs in the thalamus
9. thalamic ITNs synapse with auditory cortex where the impulse is perceived

Question 9

how is sound, a mechanical stimulus, converted into an electrical signal? 7-9

Answer 9

7. cochlear afferent neurons synapse with ITNs in the medulla oblongata
8. ITNs from medulla synapse with third order ITNs in the thalamus
9. thalamic ITNs synapse with auditory cortex where the impulse is perceived

Question 10

how is sound, a mechanical stimulus, converted into an electrical signal? 4-6

Answer 10

4. each hair cell synapses with an afferent neuron
5. afferent neurons are bundled together to make
6. the cochlear nerve

Question 11

how is sound, a mechanical stimulus, converted into an electrical signal? 1-3

Answer 11

1. sound bends inner cochlear membranes
2. bend stereocilia on hair cells
3. some hair cells depolarize, other hyperpolarize; amount of NT released from each hair cell depends on the depolarization

Question 12

why is K+ used instead of Na+ to depolarize hair cells in the ear?

Answer 12

K+ can passively move in and out of the cell. if Na+ was used, you’d need more ATP = more blood vessels = more blood flow = more vibrations = perceived as noise

Question 13

what impact does extremely loud noise or aging have on stereocilia?

Answer 13

literally wear out from bending. become fragile, break easily, and don’t regenerate.

Question 14

what is the cause of otosclerosis?

Answer 14

calcification of ear bones

Question 15

what is the cause of tinnitus?

Answer 15

damaged or misfiring of neurons between the cochlea and the brain