The Inner Ear

Question 1

The inner ear is located in the ________ part of the temporal bone

Answer 1

petrous

Question 2

List the three parts of the bony labyrinth:

Answer 2

• cochlea
• utricle and saccule
• semi-circular canal

Question 3

The fluid in the bony labyrinth is _____. It is low in ____ and high in _____.

Answer 3

Perilymph

K+ and high in Na+

Question 4

________ is produced in the blood plasma.

Answer 4

perilymph

Question 5

The cochlea has _____turns.

Answer 5

2 1/2

Question 6

The cochlea is ___cm wed and __ mm long

Answer 6

1 cm wide and 5 mm long

Question 7

The ________ labyrinth is full of endolymph which is high in ____ and low in ____

Answer 7

Membranous
K+
Na+

Question 8

________ membrane allows nutrients from the perilymph to get to the endolymph

Answer 8

reissner’s

Question 9

________ is the area between the wall of the cochlea and Reissner’s Membrane

Answer 9

Scala Vestibuli

Question 10

The Scala Media is broad at the _____ and narrow at the ______.

Answer 10

Base

Apex

Question 11

True or False: The Basilar membrane is narrow at the base and broad at the apex

Answer 11

True

Question 12

The Scala Tympani begins at the ________window

Answer 12

round

Question 13

The organ of Corti is located along the _______. Above it is the _______

Answer 13

basilar membrane

tectorial membrane

Question 14

There are a total of ______ to ________ hair cells.

Answer 14

12000 to 15000

Question 15

3/4 of hair cells are _____. 1/4 are ______.

Answer 15

OHCs

IHCs

Question 16

T or F: 90-95% of IHCs have efferent neurons

Answer 16

False - OHCs

Question 17

T or F: 90-95% of IHCs have afferent neurons

Answer 17

True

Question 18

The _________ enables stimulation of IHCs at low intensity sounds. This is done through the OHCs pulling the basilar and tectorial membrane together.

Answer 18

Cochlear amplifier

Question 19

Describe the Cochlear Amplifier

Answer 19

For low intensity sounds the movement of the basilar membrane isn’t enough for IHCs to contact the tectorial membrane. Therefore OHCs pull the tectorial and basilar membrane closer together to enable stimulation of IHCs.

Question 20

Describe the propogation of sound:

Answer 20

1) Stapes movement causes wave like movement of perilymph
2) Disturbance of movement in the scala vestibuli moves Reissner’s membrane
3) Reissner’s membrane disturbs endolymph in the cochlear duct
4) The endolymph moves the basilar membrane.

Question 21

Basilar membrane movement in response to pressure variations in the cochlea is called the ________

Answer 21

travelling waves

Question 22

Tonaticity of the Basilar membrane is the idea that: Higher freq. sounds are transduced by hair cells near the _____. Low freq. sounds are transduced by hair cells in

Answer 22

base

apex (inner most turn of the cochlea)

Question 23

T or F: The apex of the basilar membrane is wide

Answer 23

True

Question 24

T or F: Up and down movement of the tectorial membrane bends the stereocilia of IHCs

Answer 24

False- Up and down movement of the basilar membrane

Question 25

Describe how mechanical energy is transduced into electrical energy that can be used by the auditory nerve:

Answer 25

Movement of stapes moves perilymph which moves endolymph which moves the basilar membrane bending the stereocillia of the IHCs. The bending of the stereocillia changes the flow of K+ changing the intracellular potential and creating the cochlear microphonic.

Question 26

The __________ is the alternating electrical current that occurs due to the depolarization and hyperpolarization of the stereocillia of the hair cells. It enables sound to be converted to electrical energy so it can be used by the auditory nerve.

Answer 26

Cochlear Microphonic (CM)

Question 27

The synapse between the IHCs and auditory nerve are the last stage of biochemical to neural transduction. The change in polarization changes the electrical potential on each neuron. This change in electrical potential is the _________

Answer 27

Action Potential

Question 28

T or F: | Damage occurs to OHCs prior to IHCs

Answer 28

True

Question 29

List 2 possible reasons why OHCs are damaged before IHCs

Answer 29

1) The location of the OHCS | 2) The constant shearing by the tectorial membrane above the hair cells

Question 30

Which of the following is not a congenital (present from birth) inner ear problem: - Toxoplasmosis - Cochlear Dysplasias - Ototoxic drugs - Syphilis

Answer 30

- ototoxic drugs

Question 31

List the congenital (present from birth) causes of inner ear problems:

Answer 31

``` Rubella (German measles cross placental barrier) Syphilis ( if born vaginally) Toxoplasmosis Cytomegalovirus (herpes family) Cochlear Dysplasia ```

Question 32

List reasons for acquired inner ear problems:

Answer 32

``` Noise damage Disease Sudden ideopathy Ototoxic drugs Skull fractures Presbycusis Radiation treatment ```

Question 33

T or F: Most auditory info processed by each side of the brain comes from the contralateral side.

Answer 33

True

Question 34

T or F: The complex efferent system connecting the auditory cortex with the lower brain and cochlea modulates the OHCs

Answer 34

True

Question 35

Describe the Afferent Auditory Pathway

Answer 35

``` Cochlea 8th nerve - cochlea nuclei - superior olive - lateral lemniscus - Inferior Colliculi -Medial Geniculate nucleus Brain - auditory cortex ```

Question 36

T or F: 2/3 of nerve fibers go to a contralateral side from the cochlear nuclei (dorsal and ventral)

Answer 36

True

Question 37

What 2 things does the superior olive do:

Answer 37

Localization and the acoustic reflex

Question 38

The lateral lemniscus is a track of axons between the _____ and _______

Answer 38

superior olive (medulla) and inferior colliculi (midbrain)

Question 39

Where does the inferior colliculi receive input from? ( 3 places)

Answer 39

- Afferent ipsilateral - Afferent contralateral - Information from the cortex

Question 40

What 4 thingsis the inferior colliculi responsible for?

Answer 40

Temporal patterns auditory space Pitch Loudness

Question 41

The ___________ located in the thalamus is a distribution centre for sensory information and is responsible for _______

Answer 41

Medial geniculate body | auditory attention

Question 42

T or F: The auditory pathway is just a transmission system

Answer 42

False - processing occurs along the way

Question 43

T or F: cross over occurs below the cochlear nucleus and at the medial geniculate bodies

Answer 43

False - cross over occurs above the cochlear nucleus and below the medial geniculate bodies

Question 44

T or F: Tonotopic organization is maintained throughout the auditory pathway

Answer 44

True

Question 45

The Primary Auditory Cortex is _______

Answer 45

Heschl's Gyrus of the temporal lobe

Question 46

What 4 things is the Primary Auditory Cortex responsible for:

Answer 46

1) Discrimination, HZ and Temporal aspects 2) Association of sounds with past experience 3) input from other senses 4) Memory of sounds, simultaneous sounds

Question 47

What is the secondary auditory cortex responsible for?

Answer 47

Harmonic, melodic and rhythmic patterns

Question 48

T or F: The frontal and parietal lobe do some processing of sound

Answer 48

True

Question 49

List 8 possible disruptions of the Cochlear nuclei or higher:

Answer 49

``` Acoustic neuroma Auditory neuropathy Disease Toxicity Trauma Anoxia Stroke, vascular issues Degenerative Disease ```

Question 50

Humans have 23 pairs of Chromosomes: ____ pairs of autosomal and ___ pair of sex linked

Answer 50

22 pairs of autosomal | 1 pair of sex linked

Question 51

___ genes are located on chromosomes

Answer 51

30,000

Question 52

If one parent is a carrier of an autosomal dominant hearing loss the probability of the child having hearing loss is ____%

Answer 52

50%

Question 53

If both parens carry the same recessive gene for hearing loss the probability that the child will have hearing loss is ______%

Answer 53

25 to 50%

Question 54

A gene is sex linked if the mother carries the recessive gene on the ________. This primarily affects ____

Answer 54

x chromosome | Males

Question 55

____% of hearing loss is genetic

Answer 55

50%

Question 56

Of the 50% of hearing loss that is genetic: _____% is non-syndromic and _____% is syndromic

Answer 56

70% is non-syndromic | 30% is syndromic

Question 57

___% of genetic hearing loss is recessive

Answer 57

70%

Question 58

___% of genetic hearing loss is dominant

Answer 58

15%

Question 59

___% of genetic hearing loss is another type (ex. Sex linked)

Answer 59

15%

Question 60

In _________ hearing loss, hearing loss is only one symptom of several associated with the genetic syndrom. (30%)

Answer 60

Syndromic

Question 61

There are more than ______ genetic syndromes associated with hearing loss

Answer 61

400

Question 62

In ____________ hearing loss, hearing loss is the only symptom of the genetic disorder. (70%)

Answer 62

Non-syndromic hearing loss

Question 63

T or F: Syndromic hearing loss is more common than non-syndromic hearing loss

Answer 63

false- non-syndromic hearing loss is more common

Question 64

List 3 syndromes with hearing loss:

Answer 64

Usher's Treacher Collins Klippel-Feil Syndrome

Question 65

Describe Usher's syndrome:

Answer 65

The most common condition affects both hearing and vision.

Question 66

Describe Treacher Collins syndrome:

Answer 66

Mandibulofacial dyostosis. Malformed pinna, hearing loss, micrognathia, cleft palate, eye defects, underdeveloped facial bones.

Question 67

Describe Klippel-Feil Syndrome:

Answer 67

The Fusion of the vertebra. Many associated anomolies of ears, mouth, throat, larynx, face, head and organs. 30% of people with this syndrome are deaf (usually sensorineural)

Question 68

List some ethical issues with genetics:

Answer 68

Gene mapping and localization may lead to therapeutic and preventative intervention. - abortion, can help prepare ...