WEEK 8 - Topic 18 - Organ of Corti Flashcards
Where is the organ of Corti located?
The organ of Corti is attached to the basilar membrane of the cochlear duct
(REVISION) Another term for cochlear duct?
Scala media
What is the organ of Corti composed of?
The organ of Corti is composed of:
- supporting cells
- outer and inner hair cells
What attaches to the base of the hair cells in the organ of Corti?
The afferent fibres of the cochlear nerve.
What type of hair do the hair cells consist of?
Stereocilia and one kinocilium
Hair cells are what kind of receptors?
Mechanoreceptors
The hair cells of the organ of Corti protrude into what?
Endolymph
What are stereocilia?
Stereocilia are bundles of actin microfilaments covered by plasma membrane.
How many rows of inner and outer hair cells are there?
Inner hair cells: 1
Outer hair cells: 3
How are the hair cells of the organ of Corti excited?
- Bending of stereocilia towards the kinocilium opens mechanically gated ion channels in the stereocilia.
- This depolarises the hair cells, causing a graded receptor potential
- Depolarisation increases the hair cells’ release of neurotransmitter (glutamate)
What do the neurotransmitters do in the organ of Corti?
The release of neurotransmitters causes the afferent cochlear fibres to transmit impulses to the brain, where sound is perceived.
The higher the frequency, the higher the….
pitch.
The higher the amplitude, the higher the….
volume.
Outline the pathway of sound waves and the resonance of the basilar membrane
- Sound waves vibrate the tympanic membrane
- Auditory ossicles vibrate and pressure is amplified.
- Pressure waves created by the stapes pushing on the oval window move through the fluid in the scala vestibuli
4a. Sounds with frequencies below hearing travel through the helicotrema and do not excite hair cells
4b. Sounds in the hearing range go through the cochlear duct, vibrating the basilar membrane and deflecting hairs on the inner hair cells.
What happens to the basilar membrane when there are high frequency sounds?
The high-frequency sounds cause vibrations in the short stiff fibres of the basilar membrane near the base (basilar membrane is displaced).