1. ___________ = middle ear infection
Fluid behind tympanum
_______to relieve pressure and allow drainage.
“Popping ears”
Conduction deafness
Attenuation reflex

2. Scala vestibuli
Scala media
Scala tympani

4. Mechanosensitive K+ channels in Stereocilia

5. Stereocilia with mechanically-gated K+ channels

6. Activity of Hair Cells Depolarization leads to more NT release
Bend toward basal bodie or Kinocilium .....depolarization.
Note baseline level of activity.
Note action potentials in first order sensory neurons.
Depolarization leads to more NT release
Hyperpolarization leads to less NT release

7. All hair cells nearly identical
Basilar membrane thickens toward the apex

8. Base
Apex

9. Coding for Pitch = frequency = tone & Intensity
Base .... high pitch (treble)
Apex .... low pitch (bass)
Pitch coded by Intensity coded by

10. Auditory Range
Humans: ,000 Hz; optimal Hz

11. Audiogram
Decibel = unit for expressing relative loudness on a log scale
“Nerve deafness” :

12. Fourier Analysis of Complex Waves
                     
Pure sine waves

13. Pathway to Temporal Lobe
In Brainstem
Organ of
Corti Hair
Cells
Cochlear
Ganglion =
Spiral
Ganglion
Superior
Olive
Cochlear
Nuclei
VIII cranial nerve
Medial geniculate nucleus of thalamus
MG of
Thalamus
Auditory
Cortex

14. Sound Localization Low frequency High frequency
Practical Applications?

15. _________ in Auditory Cortex

16. Organs of Equilibrium

17. Semicircular Canal Angular acceleration
Three semicircular canals per ear in 3 planes

18. Utricle and Saccule
For static equilibrium
(orentation to gravity)

19. Vestibular Apparatus Hair cells
NT release dependent upon degree of bending of kinocilium and microvilli
For ampula of semi-circular canals: cupula
For utricle and saccule: otolith membrane
Stereocilia in Endolymph (Hi K+, low Na+)
A generalized hair cell
Specialized epithelial cell for transducing mechanicl to electrical
Has synaptic vesicles with basal level of release
also recieves synapses
Stereocilia bathed in endolymph (High K+, low Na+) secreted by
stia vascularis
Gradient favors K+ entry
Tips of stereocilia embedded in a gelatinous matrix.
Mechanical channels, at rest partially open, change degree of opening depending upon degree of bending of stereocilia.