The Ear Flashcards
How is pitch determined in the ear?
-Tone of sound
-Depends on the frequency of air waves
-The region of the basilar membrane that hair cells bend from gets interpreted as a sound.
How is loudness determined in the ear?
-Intensity
-Depends on the amplitude of sound waves
How is timbre determined in the ear?
-Quality
-Determined by overtones
What are the sensory receptors in the ear?
Hair cells
What is considered the external ear?
-Pinna
-Tympanic membrane (eardrum)
-External auditory canal
What is considered the middle ear?
-Ossicles
-Eustachian tube
What is considered the inner ear?
-Semicircular canals
-Utricle and saccule
-Oval window
-Vestibuloccochlear nerve
-Cochlea
-Round window
What is the role of the pinna and external auditory canal?
-Focus sound waves on the tympanic membrane
What is the role of the tympanic membrane?
-Sound waves hit membrane
-It oscillates - moving the ear ossicles
What is the role of the ear ossicles (malleus, incus, stapes)?
Amplify sound
What is the role of the eustachian tube?
Equalizes ear pressure so that the bones are properly lined up with the oval window
What does the stapes do to the oval window?
It pushes in, bulging the window out to control waves down cochlear duct
What does the cochlea contain?
-Organ of corti
-Endolymph
-Perilymph
What is the role of the cochlea?
-Transduction from waves (ripples) to APs
What does the organ of corti contain?
-Hair cells
-Basilar membrane (holds cells)
-Tectorial membrane (tips of hair cells here)
When waves come through the cochlea, what happens in the organ of corti?
-The basilar membrane moves up and down with the vibration of same frequency as the waves coming in
-This movement causes the hair cells to bend
-When hair cells bend, Na+ gates open and send APs
Name the steps of sound transduction.
- Sound waves hit tympanic membrane, which oscillates.
- Moves ear ossicles, amplifying sound.
- Oval window moves in and out, setting perilymph in motion.
- Standing waves form in perilymph, transferring into endolymph.
- Basilar membrane moves, pushing hair cell against tectorial membrane. Hair cells bend, creating GPs. APs are then sent down auditory nerve.
Conduction deafness
-Problem with amplification of sound
-Ear ossicles or tympanic membrane don’t function
-Causes include ear infection or otosclerosis
-Hearing aids will help
Sensory deafness
-Problem with hair cells or auditory nerve
-Hearing aids cannot help
-Loud music damage
What does the vestibular apparatus consist of?
-Semicircular canal
-Utricle and saccule
What does the vestivular apparatus detect?
Equilibrium: body positioning and balance
What does the vestibular nerve communicate? To where?
-Balance and posture
-Motion and orientation
-Eye movement
-To cerebellum
What do the semi-circular canals detect?
-Detect acceleration and deceleration
How do the semi-circular canals detect?
-When you spin, the endolymph doesn’t move.
-The hair cells (attached to cupula) do spin, so they get bent against the non-moving endolymph (acceleration)
-When the water eventually catches up and we’ve stopped spinning, the water will keep moving and bend the hair cells back the other way (deceleration)
-Opens ion gates and sends APs
What do the utricle and saccule detect?
-Linear motion (body position)
How do the utricle and saccule detect?
-Endolymph contains otoliths (calcium stones)
-As head moves, heavier endolymph moves forward, bending hair cells.
-Sends APs
Function of round window
The round window membrane vibrates in the opposite phase to the vibrations that enter the inner ear through the oval window. This vibration helps move fluid in the cochlea, which stimulates hair cells in the basilar membrane and allows for hearing.
Pressure waves in endolymph cause the [dropdown 1] to vibrate, which moves hair cells of
the [dropdown 2]. The hair cells touch the [dropdown 3] which bends the stereocilia and
generates nerve impulses in first-order neurons.
1: basilar membrane
2: spiral organ
3: tectorial membrane
