Chapter 53: Sense of Hearing

Question 1

The outer ends of the hair cells are fixed tightly in a rigid structure composed of a flat plate, called the

Answer 1

reticular laminae

Question 2

Stereocilia project upward from the hair cells and either touch or are embedded in the surface gel coating of the _________, which lies above the stereocilia in the scala media

Answer 2

tectorial membrane

Question 3

What structures attach tightky to the basilar fibers support the reticular lamina?

Answer 3

triangular rods of Corti

Question 4

What neurotransmitter is released by the base of hair cells at their synapse with cochlear nerve endings during depolarization?

Answer 4

glutamate

Question 5

Structure that secretes endolymph in the inner ear

Answer 5

stria vascularis

Question 6

This is generated by continual secretion of positive potassium ions into the scala media by the stria vascularis, creating an electrical potential of about +80 millivolts exists all the time between endolymph and perilymph, with positivity inside the scala media and negativity outside

Answer 6

endocochlear potential

Question 7

This is the major method used by the nervous system to detect different sound frequencies: by determining the positions along the basilar membrane that are stimulated the most

Answer 7

place principle for the determination of sound frequency

Question 8

It has been difficult to understand from the place principle how one can differentiate between low sound frequencies in the range of 200 down to 20 cycles/sec. These low frequencies have been postulated to be discriminated mainly by the so-called:

Answer 8

volley or frequency principle

Question 9

A 10-fold increase in sound energy is called

Answer 9

1 bel

Question 10

0.1 bel is equal to ___ decibel

Answer 10

1

Question 11

This condition usually occurs in the auditory canal of swimmers after prolonged exposure to cold water, leading to formation of exostosis.

Answer 11

surfer’s ear

Question 12

This a disorder of the inner ear that affects hearing and balance. The disease results from excess endolymph in the scala media and membranous labyrinth. The cause is not known, but it appears to have a genetic component. Symptoms include vertigo, nystagmus, low-pitched tinnitus, and sudden but temporary hearing loss; hearing loss can become permanent.

Answer 12

Meniere’s disease

Question 13

Retrograde pathways have been demonstrated at each level of the auditory nervous system from the brain cortex to the cochlea in the ear. The final pathway is mainly from the ________ nucleus to the sound-receptor hair cells in the organ of Corti.

Answer 13

superior olivary

Question 14

This instrument is an earphone connected to an electronic oscillator capable of emitting pure tones ranging from low frequencies to high frequencies, and it is calibrated so that zero-intensity-level sound at each frequency is the loudness that can barely be heard by the normal ear.

Answer 14

audiometer

Question 15

A common type of deafness is caused by fibrosis in the middle ear after repeated infection or by fibrosis that occurs in the hereditary disease called ___________. In either case, the sound waves cannot be transmitted easily through the ossicles from the tympanic membrane to the oval window

Answer 15

otosclerosis

Question 16

This structure is thought to regulate hydrostatic pressure of endolymph by simple expansion or collapse; it may also have secretory and absorption functions.

Answer 16

endolymphatic sac