Endocochlear potential
Encyclopedia
The endocochlear potential is the main resting potential in the cochlea
. It is a positive direct current
of 80mV which can be recorded from the endolymph
with electrodes. When a sound is presented, the endocochlear potential changes either positive or negative in the endolymph
, depending on the stimulus. The change in the potential is called the summating potential.
With the movement of the basilar membrane
, a shear force is created and a small potential is generated due to a difference in potential between the endolymph (scala media
- +80 mV) and the perilymph (vestibular and tympanic ducts- -70 mV).
An acoustic stimulus produces a simultaneous change in conductance at the membrane of the receptor cell. Because there is a steep gradient (150 mV, changes in membrane conductance are accompanied by rapid influx and efflux of ions which in turn produce the receptor potential. This is known as the Battery Hypothesis. The receptor potential for each hair cell causes a release of neurotransmitter at its basal pole, which elicits excitation of the afferent nerve fibres.
Cochlea
The cochlea is the auditory portion of the inner ear. It is a spiral-shaped cavity in the bony labyrinth, making 2.5 turns around its axis, the modiolus....
. It is a positive direct current
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...
of 80mV which can be recorded from the endolymph
Endolymph
Endolymph is the fluid contained in the membranous labyrinth of the inner ear. It is also called Scarpa's fluid, after Antonio Scarpa.-Composition:...
with electrodes. When a sound is presented, the endocochlear potential changes either positive or negative in the endolymph
Endolymph
Endolymph is the fluid contained in the membranous labyrinth of the inner ear. It is also called Scarpa's fluid, after Antonio Scarpa.-Composition:...
, depending on the stimulus. The change in the potential is called the summating potential.
With the movement of the basilar membrane
Basilar membrane
The basilar membrane within the cochlea of the inner ear is a stiff structural element that separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani .-Function:...
, a shear force is created and a small potential is generated due to a difference in potential between the endolymph (scala media
Scala media
The cochlear duct is an endolymph filled cavity inside the cochlea, located in between the scala tympani and the scala vestibuli, separated by the basilar membrane and Reissner's membrane respectively....
- +80 mV) and the perilymph (vestibular and tympanic ducts- -70 mV).
An acoustic stimulus produces a simultaneous change in conductance at the membrane of the receptor cell. Because there is a steep gradient (150 mV, changes in membrane conductance are accompanied by rapid influx and efflux of ions which in turn produce the receptor potential. This is known as the Battery Hypothesis. The receptor potential for each hair cell causes a release of neurotransmitter at its basal pole, which elicits excitation of the afferent nerve fibres.