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Endolymph
 
 
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Endolymph is the fluid contained in the membranous labyrinth
Membranous labyrinth

The membranous labyrinth is lodged within the Labyrinth and has the same general form; it is, however, considerably smaller and is partly separated from the bony walls by a quantity of fluid, the perilymph....
 of the inner ear
Inner ear

The inner ear is the labyrinth , a system of passages comprising two main functional parts:* the organ of hearing, or cochlea* and the vestibular apparatus, the organ of balance that consists of three semicircular canals and the Vestibule of the ear....
.

It is also called Scarpa's fluid, after Antonio Scarpa
Antonio Scarpa

Antonio Scarpa was an Italy anatomist and professor....
.

main cation of this unique extracellular fluid is potassium
Potassium

Potassium is a chemical element. It has the symbol K , atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash, hence the name....
, which is secreted from the stria vascularis
Stria vascularis

The upper portion of the spiral ligament contains numerous capillary loops and small blood vessels, and is termed the stria vascularis. It produces endolymph for the scala media, one of the three fluid-filled compartments of the cochlea....
. The high potassium content of the endolymph means that potassium, not sodium, is carried as the depolarizing electrical current in the hair cells. This is known as the mechano-electric transduction (MET) current.

Endolymph has a high positive charge (from 80-120 mV in the cochlea), mainly due to the presence of positively-charged amino acid
Amino acid

In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
s.






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Encyclopedia


Endolymph is the fluid contained in the membranous labyrinth
Membranous labyrinth

The membranous labyrinth is lodged within the Labyrinth and has the same general form; it is, however, considerably smaller and is partly separated from the bony walls by a quantity of fluid, the perilymph....
 of the inner ear
Inner ear

The inner ear is the labyrinth , a system of passages comprising two main functional parts:* the organ of hearing, or cochlea* and the vestibular apparatus, the organ of balance that consists of three semicircular canals and the Vestibule of the ear....
.

It is also called Scarpa's fluid, after Antonio Scarpa
Antonio Scarpa

Antonio Scarpa was an Italy anatomist and professor....
.

Composition

The main cation of this unique extracellular fluid is potassium
Potassium

Potassium is a chemical element. It has the symbol K , atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash, hence the name....
, which is secreted from the stria vascularis
Stria vascularis

The upper portion of the spiral ligament contains numerous capillary loops and small blood vessels, and is termed the stria vascularis. It produces endolymph for the scala media, one of the three fluid-filled compartments of the cochlea....
. The high potassium content of the endolymph means that potassium, not sodium, is carried as the depolarizing electrical current in the hair cells. This is known as the mechano-electric transduction (MET) current.

Endolymph has a high positive charge (from 80-120 mV in the cochlea), mainly due to the presence of positively-charged amino acid
Amino acid

In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
s. It is mainly this electrical gradient that allows potassium ions to flow into the negatively-charged hair cells during mechanical stimulation of the hair bundle. Because the hair cells are at a negative potential of about -50 mV, the electrical gradient from endolymph to hair cell is on the order of 150 mV, which is the largest electrical potential found in the body.

Pathology

Disruption of the endolymph due to jerky movements (like spinning around or driving over bumps while riding in a car) can cause motion sickness
Motion sickness

Motion sickness or kinetosis is a condition in which a disagreement exists between visually perceived movement and the vestibular system's sense of movement....
. A condition where the volume of the endolymph is greatly enlarged is called endolymphatic hydrops and has been linked to Ménière's disease
Ménière's disease

M?ni?re's disease is a disorder of the inner ear that can affect Hearing and balance. It is characterized by episodes of dizziness and tinnitus and progressive hearing loss, usually in one ear....
.

See also

  • Perilymph
    Perilymph

    Perilymph is an extracellular fluid located within the cochlea in 2 of its 3 compartments; the scala tympani and scala vestibuli. The ionic composition of perilymph is comparable to that of Blood plasma and cerebrospinal fluid....
  • Stria vascularis
    Stria vascularis

    The upper portion of the spiral ligament contains numerous capillary loops and small blood vessels, and is termed the stria vascularis. It produces endolymph for the scala media, one of the three fluid-filled compartments of the cochlea....
  • Organ of Corti
    Organ of Corti

    The organ of Corti is the organ in the inner ear of mammals that contains auditory sensory cells, or "hair cells."Structure and function...
  • Ménière's disease
    Ménière's disease

    M?ni?re's disease is a disorder of the inner ear that can affect Hearing and balance. It is characterized by episodes of dizziness and tinnitus and progressive hearing loss, usually in one ear....


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