U5 lecture 39 Flashcards
what structures make up the external ear
- external auditory canal
- auricle
- eardrum
what structures make up the middle ear
- auditory ossicles
- auditory tube
what structures make up the internal ear
- semicircular ducts
- cochlea
- saccule
- utricle
what is the function of the cochlea
hearing
what is the function of the saccule
gravity and acceleration
what is the function of the semicircular ducts
equilibrium and balance
What are the ‘steps’ of hearing
- sound wave arrives at tympanic membrane
- vibration moves auditory ossicles
- stapes depressed oval window, generates pressure wave in cochlear ducts (vestibular and tympanic)
- pressure wave distorts basilar membrane (different regions by different wavelengths)
- vibration of basilar membrane excites overlying hair cells- produces receptor potentials
what does the endolymph contain
extracellular fluid high in potassium (K+)
what is paralymph
like CSF
what do hair cells do
they are common receptors for hearing and balance/equilibrium
what are cilia on hair cells called
stereocilia
What does K+ entering from endolymph cause
auditory receptor potential
what does sensation of equilibrium/balance and hearing involve
activation of hair cells
what happens when mechanically gated channels in stereocilia membrane open
cations (K+) enter from endolymph and cause depolarization
what happens when stereocilia is bent
it pulls open the gates of ion channels
what happens in auditory transduction
- vibration of basilar membrane at different places depending on pitch
- movement of stereocilia on hair cells
- opening of mechanically gated channels
- movement of K+ into hair cells cause depolarization
- depolarization causes opening of Ca++ channels at base of hair cell
- Ca++ triggers exocytosis of neurotransmitter and depolarization of underlying sensory neurons in VIII nerve
what decibels are headphones
> 110
at what decibel can sound damage your hair cells
> 110
what do the semicircular ducts do and what are the 3 ducts called
anterior, posterior, and lateral
and they provide info on ‘X,Y,&Z’ axes
the base of each duct is enlarged to form a compartment called
ampulla
what are complex 3D movements of the head coded by
the various patterns of APs that arise from the hair cells
where do gravity and acceleration involve patterns of hair cell activation
utricle and saccule
