Term
| Describe the mechanism for determining the location of a 2,200 Hz sound arriving on the horizontal plane. |
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Definition
| Horizontal sounds above 2,000 Hz are located using interaural intensity difference. Neurons in the lateral superior olive are responsible for this. |
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Term
| A patient complains of loss of hearing. You determine that the hearing loss is due to impaired conduction. Which one of the following conditions could cause the patient's hearing impairment? |
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Definition
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Term
| A patient with multiple sclerosis has a lesion in her contral auditory pathways which affects only the axons leaving the left cochlear nucleus. Which one fo the following auditory functions will be most affected in this patient |
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Definition
| Horizontal sound localization |
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Term
| A 58 year old factory worker has been employed in the same heavy manufacturing company for 19 years. The factory floor where the man works is very noisy. Over the past few years, family members have noticed that he is increasingly hard of hearing, and they have finally persuaded him to seek medical attention. Audiometry testing revealed a pronounced loss of hearing for all sound above 5,000 Hz, with the extent of hearing loss increasing with sound frequency. Hearing for frequencies below 5,000 Hz is normal. The injury producing this hearing loss is located where? |
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Definition
| Near the base of the cochlea (bilateral) |
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Term
| Which one of the following occurs first during auditory sensory transduction? |
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Definition
| K and Ca flow into hair cells through mechanically gated channels. |
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Term
| Solve problems from http://radarproblems.com/chapters/ch06.dir/ch06pr.dir/c06p1.dir/c06p1s.htm to practice dB. |
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Definition
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Term
| What is the standard sound pressure level? |
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Definition
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Term
| What muscles are used in the attenuation reflex? |
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Definition
| Tensor tympani and stapedius. |
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Term
| True/False The attenuation reflex is used to protect your ear against loud noises such as a gun shot. |
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Definition
| False. The attenuation reflex lags 50-100 msec so it is ineffective against SUDDEN loud noises. |
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Term
| Where is perilymph and endolymph located? Be specific. |
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Definition
| Perilymph is located in the scala vestibuli and scala tympani of the cochlea. Endolymph is located in the scala media. |
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Term
| What causes prestin to change length? |
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Definition
| Changes in membrane voltage. |
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Term
| Where do hair cells synapse? |
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Definition
| Basolateral membrane contains the synaptic transmission zone which synapses on the 8th cranial nerve. |
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Term
| T/F Action potentials are generated in hair cells. |
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Definition
| Action potentials are not generated in hair cells. Instead hair cells release the neurotransmitter, glutamate, that causes afferent nerve firing. |
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Term
| If a person is riding a hover craft across level ground what vestibular organs are detecting their movement and what is the mechanism for this detection? |
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Definition
| The movement would be horizontal so the utricle would detect any linear velocity changes while the semicircular canals would detect angular velocity changes. The utricle contains a sensory epithelium the macula. The macula contains vestibular hair cells and surrounding support cells. Overlying the hair cell cilia are a gelatinous layer and a fibrous layer containing embedded otoconia. The otoconia are heavier than the surrounding fluid so that when the head is tilted or experiences linear acceleration gravity causes the otoconia to shift relative to the sensory epithelium and bend the hair cell cillia. |
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Term
| If I jump off a ledge (ledge height may vary based on test grade) what vestibular organ will detect the fall? |
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Definition
| The saccule detects acceleration on the saggital plane. |
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Term
| Assuming the test went really bad and I jumped from a really high ledge, would the saccule still detect falling when I reached maximum velocity? Why or why not? |
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Definition
| No, the saccule only detects changes in velocity, acceleration or deceleration. |
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Term
| How does the semicircular cannal detect movement? |
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Definition
Each semicircular cannal contains a swelling called an ampulla that contains a sensory epithelium a crista.
Hair cell cilia extend from the crista into gelatinous mass, the cupula. The canals of the semicircular cannals are filled with endolymph that cause the hair cells to bend when the angular velocity of the body changes. |
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Term
| Hair cell populations are paired in mirror locations. If one set of hair cells are depolarized what happens with the second? |
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Definition
| Linear acceleration in any direction always depolarizes one subpopulation of hair cells, but hyperpolarizes a second subpopulation |
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Term
| What is the orientation of hair cells within each ampula? How does this compare to hair cell orientation of the otolith organs? |
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Definition
| Hair cells are oriented in the same direction within each ampulla. Hair cells of the otoliths change direction gradually, except for at the striola where hair cells are oriented in opposite directions. |
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Term
| How are the semicircular canals paired? |
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Definition
Left horizontal and right horizontal
Right anterior and left posterior
Right posterior and left anterior |
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Term
| A person is walking down the street when they hear someone behind them call their name. They stop and look back over their right shoulder, what vestibular organs detect this movement? |
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Definition
| The utricle would detect the change in forward velocity when they person stopped. The right and left horizontal semicircular canals would detect the head turn. The right semicircular canal would depolarize, which the left would hyperpolarize. |
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Term
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Definition
Describe the peaks and platues of the previous image.
The initial peak would occur when the head was turned in the direction of that semicircular cannal. This would cause depolarization, an increase in NT release, and consequently an increase in afferent nerve firing. The platue after the initial peak would happen as accelaration decreased and then became a steady velocity. The downward spike would occur if the angular rotation was suddenly stopped. The hair cells would be hyperpolarized and afferent firing rate would drop significantly.
[image] |
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Term
| A person is riding a fast elevator down. What vestibular organ is responsible for detecting the downward acceleration? |
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Definition
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Term
| Describe which hair cells would be activated during a head rotation to the right (clockwise) |
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Definition
| If the head rotates right hair cells of the right horizontal semicircular canals would by depolarized while hair cells of the left would be hyperpolarized. |
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Term
| How does sensory transduction occur in the hair cells? |
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Definition
| When hair cells bend toward the kinocillium mechanically gated ion channels open allowing K+ and Ca2+ in. |
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Term
| A patient is tested for HVOR using caloric stimulation. The left ear tests normal however there is no response when the right ear is tested. Where could there be a problem? |
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Definition
| The right vestibular nerve is injured. |
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