Hearing And Equilibrium

Question 1

The external ear

Answer 1

Consists of pinna and the ear canal, sealed at its end by tympanic membrane (eardrum)

Question 2

Middle ear

Answer 2

Just beyond the ear drum, an air filled space connected to the pharynx by the Eustachian tube

Question 3

The inner ear

Answer 3

Contains the sensors; cochlea and vestibular apparatus

Question 4

What is the cochlea important for

Answer 4

Hearing

Question 5

What is the vestibular apparatus important for

Answer 5

Equilibrium

Question 6

What exactly is sound

Answer 6

Pressure waves

Question 7

Where is the pressure high in pressure waves? Where is the pressure low?

Answer 7

High in the peaks, low in the troughs

Question 8

Pitch

Answer 8

The frequency (number of wave peaks per second)

Question 9

What is the sound range for human ears

Answer 9

16-20,000 Hz- 10 octaves

Question 10

Where is acuity highest in human hearing

Answer 10

1000-3000 Hz

Question 11

Amplitude

Answer 11

The pressure difference between peak and trough
Main factor that determines our perception of loudness- the larger the amplitude the louder the sound

Question 12

T/F. Loudness depends entirely on amplitude

Answer 12

False, it depends on amplitude and frequency

Question 13

What does the eardrum separate

Answer 13

The outer ear from the middle ear

Question 14

Describe the path of sound vibrations

Answer 14

The eardrum will vibrate the malleus bone, moving the incus, which moves the stapes, pushing against the oval window

Question 15

What are the smallest bones in the body

Answer 15

The ossicles, three bones in the ear, the malleus, incus, and stapes which act as a lever system carrying vibrations from the eardrum to the smaller oval window

Question 16

Where are the receptor cells in the ear

Answer 16

Cochlea

Question 17

Describe the path of sound vibrations from the oval window to the cochlea and back to the middle ear

Answer 17

1. The ossicles vibrate the oval window
2. Wave energy passes through the cochlea and exits from round window to the middle ear
3. Some of the wave energy will travel through the helicatrima, into the tympanic duct while others take a short cut through cochlea duct with auditory cells (hair cells)

Question 18

The cochlear duct contains the ______

Answer 18

Organ of corti (contains auditory receptors)

Question 19

Organ of Corti

Answer 19

Sits on the basilar membrane and under the tectorial membrane
Contains auditory receptor cells- mechanoreceptors- they are epithelial cells and contain around 20,000 per cochlea

Question 20

Stereocilia

Answer 20

Each hair cell contains 50-100 stiff hair cells which extend into the tectorial membrane.

They bend when waves in perilymph deform the basilar and tectorial membranes

Question 21

When do hair cells depolarize

Answer 21

When the cilia bend toward the longest cilium, exciting a neuron and will release a neurotransmitter- activating primary sensory neuron

Axons of these neurons form the auditory nerve (cochlear nerve)- cranial nerve 8

Question 22

When do hair cells hyperpolarized

Answer 22

When its cilia bend away, releasing less transmitter and does not cause any excitation

Question 23

Where is the membrane narrow and stiff?where is wider and more flexible

Answer 23

It is narrow near the round and oval window. Wider and flexible at the helicotrema

Question 24

Fill in the blank.

high-frequency waves maximally displace the membrane at the _____ end

Answer 24

Oval window end

Question 25

How can the brain deduce the frequency

Answer 25

By paying attention to which hair cells are most active (high frequency-oval window and low frequency-helicotrema)

Question 26

Auditory signal pathway

Answer 26

Cochlear nuclei in medulla> midbrain > thalamus> auditory cortex

Question 27

Where is the primary auditory cortex located

Answer 27

In the temporal lobe

Question 28

Describe the three types of hearing loss

Answer 28

Conductive hearing loss: sound can’t be transmitted through the external or middle ear
Sensorineural hearing loss: damage to the hair cells by loud sounds or elsewhere in the inner ear.
Central hearing loss: damage to the cortex or the pathways from cochlea to cortex. Trouble recognizing and interpreting sounds

Question 29

What is the most common type of hearing loss in elderly people

Answer 29

Presbycusis- sensorineural causing by dead hair cells (can’t be replaced)

Question 30

Rinne Test

Answer 30

Hold a tuning or against mastoid bone (back of ear) and then beside the ear. Ask when the sound is louder. Normally is it louder in the ear canal, but if it is louder at the bone, it is conductive loss

Question 31

Weber Test

Answer 31

Hold the tuning fork to the patient’s forehead and then in the midline

In sensorineural loss, the sound is louder in the good ear.

With conductive loss, it is louder in the bad ear because it doesn’t have to compete with sounds heard through the ear canal

Question 32

Difference parts of the ______ sense head position and motion

Answer 32

Vestibular apparatus

Question 33

Utricle and saccule

Answer 33

Contain hair cells that are activated when the head tilts relative to gravity

Question 34

Semicircle canals

Answer 34

Fluid filled hoops that detect head rotation

Question 35

When you turn right, where will the fluid in the semicircle canals slosh to

Answer 35

Toward the left

Question 36

Where do equilibrium pathways project to

Answer 36

The cerebellum