Physiology of Hearing

Physiology of Hearing

Q. 1

Otoacoustic emissions arise from ______

 A

Outer hair cells

 B

Inner hair cells

 C

Both

 D

Organ of corti

Q. 1

Otoacoustic emissions arise from ______

 A

Outer hair cells

 B

Inner hair cells

 C

Both

 D

Organ of corti

Ans. A

Explanation:

 

Otoacoustic Emissions (OAEs)

They are low intensity sounds produced by outer hair cells of a normal cochlea and can be elicited by a very sensitive microphone placed in the external ear canal and an analysis by a computer. Sound produced by outer hair cells travels in a reverse direction:

Outer hair cells→basilar membrane→ perilymph→ oval window→ ossicles→ tympanic membrane→ ear canal.


Q. 2 Exposure to noise above—causes permanent loss of hearing:
 A 85 dB
 B 90 dB
 C 100 dB
 D 160 dB
Q. 2 Exposure to noise above—causes permanent loss of hearing:
 A 85 dB
 B 90 dB
 C 100 dB
 D 160 dB
Ans. D

Explanation:

160 dB


Q. 3

Otoacoustic emissions arise from:

 A

Inner hair cells

 B

Outer hair cells

 C

Both inner and outer hair cells

 D

Organ of Corti

Q. 3

Otoacoustic emissions arise from:

 A

Inner hair cells

 B

Outer hair cells

 C

Both inner and outer hair cells

 D

Organ of Corti

Ans. B

Explanation:

Q. 4

Increased Aldosterone leads to all of  the following, except:

 A

Hypokalemia

 B

Hypertension

 C

Hypernatremia

 D

Metabolic acidosis

Q. 4

Increased Aldosterone leads to all of  the following, except:

 A

Hypokalemia

 B

Hypertension

 C

Hypernatremia

 D

Metabolic acidosis

Ans. D

Explanation:

Increased Aldosterone is associated with metabolic alkalosis and not metabolic acidosis. Other findings associated with it includes hypokalemia (potassium excretion), hypernatremia (sodium conservation) and hypertension (characteristically diastolic).

Ref: Endocrine Physiology, 3rd Edition, Chapter 6; CURRENT Diagnosis and Treatment in Family Medicine, 3rd Edition, Chapter 36


Q. 5

Otoacoustic emissions arise from:

 A

Inner hair cells

 B

Outer hair cells

 C

Organ of corti

 D

Both outer and inner hair cells

Q. 5

Otoacoustic emissions arise from:

 A

Inner hair cells

 B

Outer hair cells

 C

Organ of corti

 D

Both outer and inner hair cells

Ans. B

Explanation:

Otoacoustic emissions arise from the outer hair cells. Otoacoustic emissions (OAE) are objective, non-invasive and rapid measures used in determining cochlear outer hair cell function.
OAE are inaudible sounds that are a byproduct of the biomechanical motility of the outer hair cells.
 

Q. 6

Otoacoustic emission arises from which of the cochlear structures?

 A

Inner hair cell

 B

Outer hair cell

 C

Riesser’s membrane

 D

Organ of otolith

Q. 6

Otoacoustic emission arises from which of the cochlear structures?

 A

Inner hair cell

 B

Outer hair cell

 C

Riesser’s membrane

 D

Organ of otolith

Ans. B

Explanation:

Otoacoustic emissions are low intensity sounds produced by outer hair cells of a normal cochlea and can be elicited by a very sensitive microphone placed in the external ear canal and an analysis by a computer.


Q. 7

Otoacoustic emissions arise from which of the following structure of the inner ear?

 A

Inner hair cells

 B

Outer hair cells

 C

Both inner and outer hair cells

 D

Organ of Corti

Q. 7

Otoacoustic emissions arise from which of the following structure of the inner ear?

 A

Inner hair cells

 B

Outer hair cells

 C

Both inner and outer hair cells

 D

Organ of Corti

Ans. B

Explanation:

Otoacoustic emissions result from the spontaneous motion of outer hair cells or from other actions of the active processes associated with outer hair cell motility. 
 
These emissions are used to access the viability of the cochlea and are used as a non invasive measure of hearing function, especially in infant hearing screening programmes. 
 

Q. 8

The mechanism of hearing and memory, include all, EXCEPT:

 A

Changes in level of neurotransmitter at synapse

 B

Increasing protein synthesis

 C

Recruitment by multiplication of neurons

 D

Spatial Reorganization of synapse

Q. 8

The mechanism of hearing and memory, include all, EXCEPT:

 A

Changes in level of neurotransmitter at synapse

 B

Increasing protein synthesis

 C

Recruitment by multiplication of neurons

 D

Spatial Reorganization of synapse

Ans. C

Explanation:

Neurons are ‘permanent cells’ that do not undergo mitotic division in post natal life. The production of neurons stop shortly after birth.

Ref: Neurons and Networks: An Introduction to Behavioral Neuroscience By John E. Dowling; Ganong’s Review of Medical Physiology, 22nd Edition, Page 259, 270; Robbins Pathologic Basis of Disease, 7th Edition, Page 91

 


Q. 9

The limit of loudness expressed as decibels that people can tolerate without substantial damage to their hearing is –

 A

55

 B

65

 C

75

 D

85

Q. 9

The limit of loudness expressed as decibels that people can tolerate without substantial damage to their hearing is –

 A

55

 B

65

 C

75

 D

85

Ans. D

Explanation:

Ans. is ‘d’ i.e., 85 


Q. 10

Foetus starts hearing by what time in intrauterine life: 

 A

14 weeks

 B

20 weeks

 C

32 weeks

 D

33 weeks

Q. 10

Foetus starts hearing by what time in intrauterine life: 

 A

14 weeks

 B

20 weeks

 C

32 weeks

 D

33 weeks

Ans. B

Explanation:

Q. 11

Sense organ for hearing is

 A

Organ of Corti

 B

Cristae

 C

Macula

 D

None

Q. 11

Sense organ for hearing is

 A

Organ of Corti

 B

Cristae

 C

Macula

 D

None

Ans. A

Explanation:

Q. 12

Bones of middle ear are responsible for which of the following?

 A

Amplification of sound intensity

 B

Reduction of sound intensity

 C

Protecting the inner ear

 D

Reduction of impedance to sound transmission

Q. 12

Bones of middle ear are responsible for which of the following?

 A

Amplification of sound intensity

 B

Reduction of sound intensity

 C

Protecting the inner ear

 D

Reduction of impedance to sound transmission

Ans. D

Explanation:

 

Broadly hearing mechanism can be divided into:

  • Mechanical conduction of sound (done by middle ear).
  • Transduction of mechanical energy into electrical impulses (done by sensory system of cochlea)
  • Conduction of electrical impulse to brain (i.e. auditory pathway)

i. Conduction of sound:

  • It is done mainly by middle ear. Middle ear not just simply conducts the sound but converts sound of great amplitude and less force to that of less amplitude and greater force.
  • This function of the middle ear is called as impedance matching mechanism or the transformer action.

ii. Transduction of mechanical energy to electrical impulse:

  • Movements of the stapes footplate causes vibrations in scala vestibuli followed by scala tympani and is transmitted to the cochlear fluids which brings about movement of the basilar membrane.
  • This sets up shearing force between the tectorial membrane and the hair cells.
  • The distortion of hair cells gives rise to electrical nerve impulse.

 

A sound wave, depending on its frequency, reaches maximum amplitude on a particular place on the basilar membrane, and stimulates that segment (traveling wave theory of von Bekesy).

Higher frequencies are represented in the basal turn of cochlea and the progressively lower one toward the apex.


Q. 13

Impedance matching occurs at

 A

Difference of surface are of tympanic membrane and foot plate

 B

Semicircular canal fluid

 C

Utricle and Saccule

 D

None

Q. 13

Impedance matching occurs at

 A

Difference of surface are of tympanic membrane and foot plate

 B

Semicircular canal fluid

 C

Utricle and Saccule

 D

None

Ans. A

Explanation:

 

The area of tympanic membrane is much larger than area of stapes footplate, the average ratio being 21:1.

As the effectice vibratory area of tympanic membrane is only two thirds, the effectives areal ratio is reducted to 14:1 which helps in impedance matching/ transformer action.


Q. 14

Primary receptor cells of hearing is

 A

Supporting cell

 B

Tectorial membrane

 C

Tunnel of Corti

 D

Hair cell

Q. 14

Primary receptor cells of hearing is

 A

Supporting cell

 B

Tectorial membrane

 C

Tunnel of Corti

 D

Hair cell

Ans. D

Explanation:

 

Hair cells: are important receptor cells of hearing and transduce sound energy into electrical energy.


Q. 15

True about Otoacoustic emissions:

 A

Are by product of outer hair cell

 B

Are by product of inner hair cell

 C

Used as a screening test of hearing in newborn infant

 D

a and c

Q. 15

True about Otoacoustic emissions:

 A

Are by product of outer hair cell

 B

Are by product of inner hair cell

 C

Used as a screening test of hearing in newborn infant

 D

a and c

Ans. D

Explanation:


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