Ear Flashcards
1
Q
contrast perilymph vs endolymph
A
- perilymph:
- fluid in the bony labryinth
- resembles extracellular fluid (and CSF) in composition with high Na and low K
- endolymph
- fluid in the membranous labyrinth
- similar in composition to intracellular fluid (low Na and high K)
2
Q
describe the semicircular canal
A
- the anterior, posterior and lateral semicircular canals are tubes within temporal bone (bony labyrinth)
- attached to the vestibule by an expanded ampulla
- the bony labyrinth is filled with perilymph
- the membranous labyrinth within is semicircular duct
- semicircular ducts contain endolymph
3
Q
describe the vestibule
A
- large irregular central cavity
- has the oval and round windows on the lateral wall that lead inot the adjacent cochlear canal
- represents the bony labyrinth
- membranous labyrinth within are:
- utricle
- saccule
4
Q
describe the cells of the membranous labyrinth
A
- sensory hair cells
- project into endolymphatic space
- supporting cells
5
Q
describe the hair cells of vestibular labyrinths
A
- mechano-electric transducers
- rigid projections on their apical surfaces = stereocilia
- hair bundle = rows of stereocilia
- made of actin filaments
- increase in height in one particular direction
- single true cilium = kinocilium
- kinocilium is located behind the tallest row of stereocilia
- microtubules found within
6
Q
A
7
Q
describe the role of crista ampullaris in positioning
A
delfection of stereocilia during angular accleration of the head
8
Q
describe maculae
A
- contained within utricle and saccule
- sensors of gravity and linear acceleration of head
- cells of the epithelium face the endolymph
- gelatinous polysaccharide material over the epi. - otolithic membrane (OM)
- outer aspect of OM crystalline bodies of calcium carbonate and protein - otoconia
9
Q
describe the function of maculae in positioning
A
- deflection of stereocilia during linear acceleration of the head
- head bent forward
10
Q
describe the cochlear duct (membranous labyrinth)
A
contains the spiral organ of Corti which lies on the basilar membrane
- vestibular membrane (Reissner’s): separates the scala media from the scala vestibule
- stria vascularis: responsible for the ionic composition of the endolymph
- organ of Corti (receptor for hearing): contains neuroepithelial hair cells - rests on the basilar membrane
11
Q
describe the organ of Corti
A
- presence of stereocilia
- tips of these hair cells embedded in tectorial membrane
- pillar cells occupies region between inner and outer hair cells, thus forming the inner tunnel
12
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13
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14
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15
Q
contrast conduction vs sensorineural deafness
A
- conduction deafness
- pathway of sound conduction is blocked
- sensorineural deafness
- destruction of nerve (sensory neuroepithelial) cells or central pathway to the brain