The Inner Ear Flashcards
The inner ear is located in the ________ part of the temporal bone
petrous
List the three parts of the bony labyrinth:
- cochlea
- utricle and saccule
- semi-circular canal
The fluid in the bony labyrinth is _____. It is low in ____ and high in _____.
Perilymph
K+ and high in Na+
________ is produced in the blood plasma.
perilymph
The cochlea has _____turns.
2 1/2
The cochlea is ___cm wed and __ mm long
1 cm wide and 5 mm long
The ________ labyrinth is full of endolymph which is high in ____ and low in ____
Membranous
K+
Na+
________ membrane allows nutrients from the perilymph to get to the endolymph
reissner’s
________ is the area between the wall of the cochlea and Reissner’s Membrane
Scala Vestibuli
The Scala Media is broad at the _____ and narrow at the ______.
Base
Apex
True or False: The Basilar membrane is narrow at the base and broad at the apex
True
The Scala Tympani begins at the ________window
round
The organ of Corti is located along the _______. Above it is the _______
basilar membrane
tectorial membrane
There are a total of ______ to ________ hair cells.
12000 to 15000
3/4 of hair cells are _____. 1/4 are ______.
OHCs
IHCs
T or F: 90-95% of IHCs have efferent neurons
False - OHCs
T or F: 90-95% of IHCs have afferent neurons
True
The _________ enables stimulation of IHCs at low intensity sounds. This is done through the OHCs pulling the basilar and tectorial membrane together.
Cochlear amplifier
Describe the Cochlear Amplifier
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.
Describe the propogation of sound:
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.
Basilar membrane movement in response to pressure variations in the cochlea is called the ________
travelling waves
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
base
apex (inner most turn of the cochlea)
T or F: The apex of the basilar membrane is wide
True
T or F: Up and down movement of the tectorial membrane bends the stereocilia of IHCs
False- Up and down movement of the basilar membrane
Describe how mechanical energy is transduced into electrical energy that can be used by the auditory nerve:
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.
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.
Cochlear Microphonic (CM)
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 _________
Action Potential
T or F:
Damage occurs to OHCs prior to IHCs
True
List 2 possible reasons why OHCs are damaged before IHCs
1) The location of the OHCS
2) The constant shearing by the tectorial membrane above the hair cells
Which of the following is not a congenital (present from birth) inner ear problem:
- Toxoplasmosis
- Cochlear Dysplasias
- Ototoxic drugs
- Syphilis
- ototoxic drugs
List the congenital (present from birth) causes of inner ear problems:
Rubella (German measles cross placental barrier) Syphilis ( if born vaginally) Toxoplasmosis Cytomegalovirus (herpes family) Cochlear Dysplasia
List reasons for acquired inner ear problems:
Noise damage Disease Sudden ideopathy Ototoxic drugs Skull fractures Presbycusis Radiation treatment
T or F: Most auditory info processed by each side of the brain comes from the contralateral side.
True
T or F: The complex efferent system connecting the auditory cortex with the lower brain and cochlea modulates the OHCs
True
Describe the Afferent Auditory Pathway
Cochlea 8th nerve - cochlea nuclei - superior olive - lateral lemniscus - Inferior Colliculi -Medial Geniculate nucleus Brain - auditory cortex
T or F: 2/3 of nerve fibers go to a contralateral side from the cochlear nuclei (dorsal and ventral)
True
What 2 things does the superior olive do:
Localization and the acoustic reflex
The lateral lemniscus is a track of axons between the _____ and _______
superior olive (medulla) and inferior colliculi (midbrain)
Where does the inferior colliculi receive input from? ( 3 places)
- Afferent ipsilateral
- Afferent contralateral
- Information from the cortex
What 4 thingsis the inferior colliculi responsible for?
Temporal patterns
auditory space
Pitch
Loudness
The ___________ located in the thalamus is a distribution centre for sensory information and is responsible for _______
Medial geniculate body
auditory attention
T or F: The auditory pathway is just a transmission system
False - processing occurs along the way
T or F: cross over occurs below the cochlear nucleus and at the medial geniculate bodies
False - cross over occurs above the cochlear nucleus and below the medial geniculate bodies
T or F: Tonotopic organization is maintained throughout the auditory pathway
True
The Primary Auditory Cortex is _______
Heschl’s Gyrus of the temporal lobe
What 4 things is the Primary Auditory Cortex responsible for:
1) Discrimination, HZ and Temporal aspects
2) Association of sounds with past experience
3) input from other senses
4) Memory of sounds, simultaneous sounds
What is the secondary auditory cortex responsible for?
Harmonic, melodic and rhythmic patterns
T or F: The frontal and parietal lobe do some processing of sound
True
List 8 possible disruptions of the Cochlear nuclei or higher:
Acoustic neuroma Auditory neuropathy Disease Toxicity Trauma Anoxia Stroke, vascular issues Degenerative Disease
Humans have 23 pairs of Chromosomes: ____ pairs of autosomal and ___ pair of sex linked
22 pairs of autosomal
1 pair of sex linked
___ genes are located on chromosomes
30,000
If one parent is a carrier of an autosomal dominant hearing loss the probability of the child having hearing loss is ____%
50%
If both parens carry the same recessive gene for hearing loss the probability that the child will have hearing loss is ______%
25 to 50%
A gene is sex linked if the mother carries the recessive gene on the ________. This primarily affects ____
x chromosome
Males
____% of hearing loss is genetic
50%
Of the 50% of hearing loss that is genetic: _____% is non-syndromic and _____% is syndromic
70% is non-syndromic
30% is syndromic
___% of genetic hearing loss is recessive
70%
___% of genetic hearing loss is dominant
15%
___% of genetic hearing loss is another type (ex. Sex linked)
15%
In _________ hearing loss, hearing loss is only one symptom of several associated with the genetic syndrom. (30%)
Syndromic
There are more than ______ genetic syndromes associated with hearing loss
400
In ____________ hearing loss, hearing loss is the only symptom of the genetic disorder. (70%)
Non-syndromic hearing loss
T or F: Syndromic hearing loss is more common than non-syndromic hearing loss
false- non-syndromic hearing loss is more common
List 3 syndromes with hearing loss:
Usher’s
Treacher Collins
Klippel-Feil Syndrome
Describe Usher’s syndrome:
The most common condition affects both hearing and vision.
Describe Treacher Collins syndrome:
Mandibulofacial dyostosis. Malformed pinna, hearing loss, micrognathia, cleft palate, eye defects, underdeveloped facial bones.
Describe Klippel-Feil Syndrome:
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)
List some ethical issues with genetics:
Gene mapping and localization may lead to therapeutic and preventative intervention.
- abortion, can help prepare …
