Physiology of Hearing Flashcards
What are mechanoreceptors?
- a somatosensory receptors
- relay extracellular stimulus to intracellular signal transduction through mechanically gated ion channels
- external stimuli are usually in the form of touch, pressure, stretching, sound waves, and motion
What is the normal range of sound that humans can hear?
1 - 5-6 decibels
2 - 15-20 decibels
3 - 50-60 decibels
4 - 115-130 decibels
3 - 50-60 decibels
Repeated high DB can damage hearing
Is the inner ear more sensitive to air or bone conduction?
- Air conduction
Label the 2 parts of the inner ear in the image below, numbered 1-2?
vestibule (with semi-circle canals)
cochlea
1 - cochlea
2 - vestibular apparatus (vestibular and semi-circle canals)
The ossicles in the middle ear are important for transmitting the vibrations from sound waves from the outer ear to the inner ear. What is the stapes connected to?
1 - oval window
2 - temporal bone
3 - tympanic membrane
4 - pinna
1 - oval window
Also stapedius muscle
The ossicles in the middle ear are important for transmitting the vibrations from sound waves from the outer ear to the inner ear. What is the malleus connected to?
1 - oval window
2 - temporal bone
3 - tympanic membrane
4 - pinna
3 - tympanic membrane
Also tympanic muscle
There are 2 labyrinths in the inner ear, and both contain fluid. What are the names of the labyrinths and what fluid is contained within each?
- bony labyrinth = perilymph
- membranous labyrinth = endolymph
There are 2 labyrinths in the inner ear, the bony and membranous labyrinth, which contain perilymph and endolymph, respectively. Match the following with the fluids:
- perilymph
- endolymph
= high Na+ and low K+ similar to extracellular fluid
= high K+ and low Na+ similar to extracellular fluid
perilymph = high Na+ and low K+ similar to extracellular fluid
endolymph = high K+ and low Na+ similar to extracellular fluid
Which nerve is in direct contact with the cochlea, and which cranial nerve (CN) is this a branch of?
1 - cochlea branch of vestibulocochlear nerve
2 - vestibular branch of vestibulocochlear nerve
3 - chorda tympani branch of vestibulocochlear nerve
4 - all of the above
1 - cochlea branch of vestibulocochlear nerve
CN 8
Which spongy bone does the cochlea nerve and the spiral ganglion sit inside?
1 - modiolus bone
2 - temporal bone
3 - zygomatic bone
4 - mandiubular bone
1 - modiolus bone
The tubes of the cochlea are actually composed of 3 separate tubes. Label the tubes and the membrane using the labels below and what they contain (fluid wise).
- Scala vestibuli (perilymph)
- Scala media/cochlear duct (endolymph and the organ of Corti)
- Scala tympani (perilymph)
- basilar membrane
1 = scala vestibuli (perilymph) 2 = scala media/cochlear duct (endolymph and organ of Corti) 3 = scala tympani (perilymph) 4 = basilar membrane
What is the spiral ganglion?
- group of cell bodies
- neurons axons supply the hairs of the organ of corti
- synapses with the cochlea nerve
Of the 3 parts of the cochlea below, which 2 are are directly connected to the middle ear?
- scala vestibuli (perilymph)
- scala media/cochlear duct (endolymph and organ of Corti)
- scala tympani (perilymph)
- scala tympani connects with round window
- scala vestibuli connects with oval window
When we look at the middle tube of the cochlea, the scala media/cochlear duct, there are 2 membranes, one above and one below. What are these called?
1 - top membrane = vestibular membrane (close to scala vestibuli)
2 - bottom membrane = basilar membrane
The organ of corti contains mechanoreceptor hair cells, which include an inner and outer layer. Which of there layers is important for the following:
- sensory nerve fibres in charge of auditory transduction
- motor nerve fibre from the brain to contract or loosen the basilar membrane
- inner = sensory nerve fibres in charge of auditory transduction
- outer = motor nerve fibre from the brain to contract or loosen the basilar membrane (if its a loud noise then this is loosened so we don’t hear as much, but if its a whisper it tightens to accentuate the sound)
What is the tectorial membrane?
1 - gel like membrane attached to the modiolus at one end and free on the other end
2 - gel like membrane between basilar membrane and the hair cells
3 - gel like membrane surrounding the organ of corti
1 - gel like membrane attached to the modiolus at one end and free on the other end
- runs parallel to the basilar membrane throughout the cochlea with hair cells between the 2
- in direct contact with the stereocilia (cilia) of hair cells contained within the organ of corti
When vibrations move through the perilymph contained within the scala vestibuli and scale tympani they create movement to the basilar membrane, which causes what to happen?
1 - basilar membrane moves and pushes hair cells into the tectorial membrane
2 - vestibular membrane pushes tectorial membrane down into hair cells
3 - basilar membrane tightens and tectorial membrane will move down into the hair cells
4 - basilar membrane loosens and tectorial membrane will move down into the hair cells
1 - basilar membrane moves and pushes hair cells into the tectorial membrane
- stereocilia at top of hair cells and the organ of corti are pressed into the tectorial membrane
When vibrations move through the perilymph contained within the scala vestibuli and scale tympani they create movement in the basilar membrane, causing the stereocilia of the hair cells and the organ of corti to press against the tectorial membrane. What does this do to the stereocilia of the hair cells?
1 - as soon as hair cells touch tectorial membrane, Na+ channels open
2 - hair cells trigger and intracellular pathway that will lead to an electrical signal
3 - tip link between adjacent stereocilia lean against one another opening mechanical gated K+ channels to open
3 - tip link between adjacent stereocilia lean against one another opening mechanical gated K+ channels to open