Auditory System Quiz

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Questions and Answers

What type of hair cells are primarily responsible for hearing?

Efferent hair cells

Sensory hair cells

Inner hair cells (correct)

Outer hair cells

What happens to outer hair cells when efferent fibers of the auditory nerve are stimulated?

They lengthen and increase sensitivity

They shorten and affect inner hair cell sensitivity (correct)

They die and cause complete hearing loss

They remain unchanged and do not affect hearing

Presbyacusis primarily affects which type of sound frequencies?

High frequencies (correct)

All frequencies equally

Medium frequencies

Low frequencies

How does the basilar membrane’s structure relate to sound frequency perception?

Narrow and stiff for high frequencies Signup and view all the answers

What reliable cue do ears use to localize low frequency sounds?

Difference in arrival time to each ear Signup and view all the answers

Which structure is NOT part of the auditory pathway?

Cochlear nucleus Signup and view all the answers

Why does destruction of one side of the auditory cortex not result in complete deafness?

Cross connections allow compensatory processing Signup and view all the answers

Which part of the brain is responsible for processing sound and contains maps for different frequencies?

Primary auditory area Signup and view all the answers

What is the nature of sound waves and their ability to travel?

Sound waves can be transmitted through solids, liquids, and gases. Signup and view all the answers

Which frequency range represents the most sensitive human hearing perception?

1000 Hz to 4000 Hz Signup and view all the answers

What determines the loudness of a sound?

The amplitude of sound waves. Signup and view all the answers

Which component in the ear is responsible for sound amplification?

Ossicles Signup and view all the answers

What is the consequence of sound reaching 140 dB?

It may cause discomfort and damage to hearing receptors. Signup and view all the answers

What measurement unit is used to express loudness?

Decibels (dB) Signup and view all the answers

What role does the Eustachian tube play in the ear?

Equalizes pressure in the middle ear. Signup and view all the answers

How is the total amplification of sound achieved in the ear?

By the lever system of the ossicles and the size ratio of the tympanic membrane to the oval window. Signup and view all the answers

What function does the middle ear reflex primarily serve?

Protecting the inner ear from loud sounds Signup and view all the answers

What is the primary difference between perilymph and endolymph?

Perilymph is similar in composition to extracellular fluid, while endolymph has a unique ionic composition Signup and view all the answers

Which muscle of the middle ear is innervated by cranial nerve VII?

Stapedius Signup and view all the answers

What occurs during the mechanism of hearing due to sound waves?

Vibrations of the basilar membrane cause bending of hair cells' stereocilia Signup and view all the answers

What is the latent period of the acoustic reflex, during which it cannot protect the inner ear?

100 ms Signup and view all the answers

Where is the organ of Corti located?

Inside the scala media Signup and view all the answers

What is the result of potassium influx into hair cells?

Excitation (depolarization) of the afferent cochlear nerve fibers Signup and view all the answers

What is the role of the tensor tympani muscle in the middle ear?

It pulls the malleus inward when contracted Signup and view all the answers

Which location houses the hair cells responsible for detecting head movement in the semicircular canals?

Crista ampullaris Signup and view all the answers

What happens to the capula during head rotation?

It lags and moves to the opposite direction of head movement. Signup and view all the answers

What is the effect of the capula bending away from the kinocilium?

Inhibition of hair cells. Signup and view all the answers

What occurs when endolymph moves during caloric stimulation with cold water?

Nystagmus is generated toward the opposite side. Signup and view all the answers

What phenomenon describes the sensation of rotation without actual movement?

Vertigo Signup and view all the answers

How does the frequency of action potentials change during head rotation?

They increase to a peak before returning to basal levels. Signup and view all the answers

What latent effect occurs if a person stops rotating suddenly?

Continued inhibition of one semicircular canal. Signup and view all the answers

How do the semicircular canals function in pairs?

One canal is always inhibited while the other is excited. Signup and view all the answers

What is the primary function of the vestibular system?

Maintaining body balance and controlling eye movement Signup and view all the answers

Which chamber is responsible for sensing linear vertical acceleration?

Saccule Signup and view all the answers

What role does the kinocilium play in the sensory process of the macula?

Influences the cilia's response to tilt direction Signup and view all the answers

What is the composition of the space between the osseous and membranous labyrinth in the vestibular system?

Perilymph Signup and view all the answers

How does the bending of cilia affect hair cell excitation in the vestibular system?

Bending toward kinocilium leads to excitation Signup and view all the answers

What is the primary responsibility of Wernicke's area in the secondary auditory area?

Interpreting sounds and understanding language Signup and view all the answers

Which part of the vestibular system is responsible for detecting angular acceleration?

Semicircular canals Signup and view all the answers

What does the macula contain that is essential for its sensory function?

Cilia and stereocilia embedded in gelatinous membrane Signup and view all the answers

Which of the following describes the function of the vestibulo-ocular reflex (VOR)?

Stabilizes the retinal image during head rotation Signup and view all the answers

What is the primary role of the vestibular system?

To maintain body posture and balance through the perception of movement in 3D Signup and view all the answers

During physiologic nystagmus, what occurs after the eyes reach an extreme position during prolonged head rotation?

Eyes return rapidly to the starting position to begin another cycle Signup and view all the answers

What happens when the right horizontal semicircular canal is stimulated while the head rotates to the right?

Inhibition of the left horizontal canal Signup and view all the answers

Which cranial nerves are involved in the pathways from the vestibular nuclei?

III, IV, and VI Signup and view all the answers

What type of movement is characterized as slow and occurs opposite to the direction of head rotation during nystagmus?

Slow phase movement Signup and view all the answers

Which structure terminates the vestibular nerve?

The vestibular nuclei in the brain stem Signup and view all the answers

In the context of the vestibular system, what role do the extra-ocular muscles serve during head rotation?

They stabilize the visual field by counteracting head movements Signup and view all the answers

Study Notes

The Ear

The ear is a mechanoreceptive organ containing mechanoreceptors.
It functions in hearing (responding to sound waves) and equilibrium (balance).
Sound waves comprise vibrations of air molecules, characterized by peaks (maximum compression) and troughs (maximum rarefaction).
Sound waves can travel through liquids, solids, and gases, but not vacuum.

Qualities of Sound

Pitch: Related to frequency (number of sound waves passing a fixed point per second, measured in Hertz (Hz)).
Human hearing range is 20-20,000 Hz, most sensitive to 1000-4000 Hz (human speech).
Loudness (intensity): Related to the amplitude of sound waves (difference between maximum and minimum pressure).
Measured in decibels (dB). Zero decibels represents the standard intensity.
An x-fold increase in sound intensity corresponds to an increase in dB of 10*log(x).
Normal conversation is roughly 60 dB.
Discomfort and damage to hearing receptors occur around 140 dB.
Pain occurs at around 160 dB.

Direction of Sound

Determined by the spatial relationship between the sound source and the listener.

Physiologic Anatomy

Outer Ear: Pinna (collects and directs sound), external auditory meatus.
Middle Ear: Tympanic membrane (eardrum); ossicles (malleus, incus, stapes) and associated muscles (stapedius and tensor tympani).
Inner Ear: Cochlea (sensory organ of hearing), Eustachian tube.

Amplification of Sound

The ossicles act as a lever system, amplifying sound energy transfer from the air to the denser liquid medium in the inner ear.
The surface area of the tympanic membrane is significantly larger than that of the oval window, providing further amplification.

Attenuation (Acoustic) Reflex

Loud sounds trigger a reflex contraction of muscles in the middle ear.
This reflex decreases transmission of low-frequency sounds to protect the inner ear from damage by sudden loud sounds.
Helps to mask low-frequency background noise.

Cochlea

The cochlea is a spiraled tube divided into three sections by membranes.
The scala vestibuli and scala tympani contain perilymph.
The scala media contains endolymph.
Inside the scala media is the organ of Corti, containing hair cells with stereocilia.
Perilymph has similar composition to extracellular fluid (ECF), with high sodium and low potassium.
Endolymph has high potassium and low sodium levels.

Hair Cells

Inner hair cells are the primary sensory cells for hearing.
Outer hair cells are involved in amplifying the response of inner hair cells.
Damage to hair cells can result in hearing loss.

Pitch Discrimination

Pitch is determined by which part of the basilar membrane vibrates.
The base of the membrane vibrates to high-frequency sounds and the apex to low-frequency sounds.
Basilar fibers at the base are short and stiff, while those at the apex are long and flexible.

Auditory Pathway

Auditory information travels from the cochlea through various nuclei (e.g., superior olivary nucleus, lateral lemniscus, inferior colliculus, medial geniculate body) before reaching the auditory cortex.

Cortical Auditory Areas

Primary auditory areas are located in the superior temporal lobe.
These areas receive information from the medial geniculate body.
Secondary auditory areas are located near the primary areas, integrating sound information with other sensory inputs.

Vestibular System

Located in the inner ear, it consists of utricle, saccule, and semicircular canals.
Responsible for balance (equilibrium) and spatial orientation, responding to head position and movement.
The utricle and saccule detect linear acceleration and head position.
Semicircular canals detect angular acceleration (rotation).
The macula within utricle and saccule contains hair cells embedded in a gelatinous matrix containing calcium carbonate crystals (otoconia), which shift position with changes in head orientation.
Displacement of otoconia or endolymph bending cilia cause hair cells to become stimulated or inhibited, leading to afferent signal generation in peripheral vestibular afferents.

Caloric Stimulation of the Vestibular Apparatus

Irrigation of the ear with hot or cold water causes endolymph movement.
This movement stimulates the horizontal semicircular canals (in opposite directions based on water temperature).
This stimulation can cause nystagmus (involuntary eye movements), suggesting the direction of head movement.

Vestibulo-ocular Reflex (VOR)

Reflex that stabilizes retinal images during head rotation.
Eyes move in the opposite direction of head rotation to maintain visual focus

Additional Notes

Damage to the vestibular system can cause vertigo and balance disorders.

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Description

Test your knowledge on the auditory system through this quiz, which covers the functions of hair cells, sound frequency perception, and the brain's role in processing sound. Questions will explore topics such as presbyacusis, sound wave properties, and the structures involved in hearing.