Fluid of inner ear

Fluid Of Inner Ear

Q. 1

Endolymph in the inner ear:

 A

Is a filterate of blood serum

 B

Is secreted by Stria vascularis

 C

Is secreted by Basilar membrane

 D

Is secreted by Hair cells

Q. 1

Endolymph in the inner ear:

 A

Is a filterate of blood serum

 B

Is secreted by Stria vascularis

 C

Is secreted by Basilar membrane

 D

Is secreted by Hair cells

Ans. B

Explanation:

Is secreted by Stria vascularis [Ref: Ds. of ENT by P.L. Dhingra 5/e p12] Repeat from May 09

There are 2 main fluids in the inner ear:

  • Endolymph

– It fills the entire membranous labyrinth

– Resembles intracellular. fluid, being rich in K ions.

–  It is secreted by the secretory cells of the stria vascularis of the choclea and by the dark cells (present in the utricle and near the ampullated ends of semicircular ducts).

  • Perilymph

–  It fills the space between the bony and the membranous labyrinth.

–  It resembles extra cellular fluid being rich in Na ions.

– It communicates with CSF through the aqueduct of cochlea which opens into the scala tympani near the round window.

– There are 2 views regarding its formation:

i)    It is a filterate of blood serum and is formed by capillaries of the spiral ligament

ii)     It is a direct continuation of CSF and reaches the labyrinth via aqueduct of cochlea.


Q. 2

Which of the following structures contains endolymph?

 A

Helicotrema

 B

Scala media

 C

Scala tympani

 D

Scala vestibuli

Q. 2

Which of the following structures contains endolymph?

 A

Helicotrema

 B

Scala media

 C

Scala tympani

 D

Scala vestibuli

Ans. B

Explanation:

The cochlea of the inner ear is a coiled structure filled with endolymph and perilymph. Within it are three longitudinal compartments. The membranous labyrinth within the cochlea is called the scala media, or cochlear duct. This compartment contains the hair receptors and is filled with endolymph that is secreted by the stria vascularis. The composition of endolymph resembles intracellular fluid (K+> Na+).

The two perilymph-filled compartments, the scala tympani and the scala vestibuli surround the cochlear duct. This space is continuous with subarachnoid space, and therefore the perilymph closely resembles cerebrospinal fluid. The helicotrema is the apical connection between the scala tympani and scala vestibuli.
 
The spiral ganglion is located in the modiolus (the cochlear part of the body labyrinth), and contains the cell bodies of the bipolar cells that comprise the cochlear division of the eighth nerve.

Q. 3

Endolymph in the inner ear:

 A

 has low concentration of K+ and high concentration of Na+

 B

Is secreted by Stria vascularis

 C

Is secreted by Basilar membrane

 D

None is true

Q. 3

Endolymph in the inner ear:

 A

 has low concentration of K+ and high concentration of Na+

 B

Is secreted by Stria vascularis

 C

Is secreted by Basilar membrane

 D

None is true

Ans. B

Explanation:

Endolymph is formed in the scala media by the stria vascularis. Endolymph has high concentration of K+ and low concentration of Na+.

Cells in the stria vascularis have high concentration of Na+ K+ ATPase activity. 

Q. 4

Endolymphatic duct drains into :

 A

Subdural space

 B

External space

 C

Subarachnoid space

 D

Succulus

Q. 4

Endolymphatic duct drains into :

 A

Subdural space

 B

External space

 C

Subarachnoid space

 D

Succulus

Ans. A

Explanation:

Ans:A.)Subdural 

Perilymph drains into subarachnoid space through the aqueduct of cochlea… 
Endolymph is absorbed in subdural space.


Q. 5

Site where endolymph is seen:

 A

Scala vestibuli

 B

Scala media

 C

Helicotrema

 D

Organ of corti

Q. 5

Site where endolymph is seen:

 A

Scala vestibuli

 B

Scala media

 C

Helicotrema

 D

Organ of corti

Ans. B

Explanation:

Q. 6

The function of stria vascularis is:

 A

To produce perilymph

 B

To absorb perilymph

 C

To maintain electric milieu of endolymph

 D

To maintain electric milieu of perilymph

Q. 6

The function of stria vascularis is:

 A

To produce perilymph

 B

To absorb perilymph

 C

To maintain electric milieu of endolymph

 D

To maintain electric milieu of perilymph

Ans. C

Explanation:

 

Scala vestibuli and scala tympani are filled with perilymph, whereas scala media/membranous cochlea is filled with endolymph. 


Q. 7

Endolymph in the inner ear:

 A

Is a filterate of blood serum

 B

Is secreted by stria vascularis

 C

Is secreted by basilar membrane

 D

Is secreted by hair cells

Q. 7

Endolymph in the inner ear:

 A

Is a filterate of blood serum

 B

Is secreted by stria vascularis

 C

Is secreted by basilar membrane

 D

Is secreted by hair cells

Ans. B

Explanation:

Q. 8

Endolymph is rich in ‑

 A

Na+

 B

Cl

 C

HCO3

 D

K+

Q. 8

Endolymph is rich in ‑

 A

Na+

 B

Cl

 C

HCO3

 D

K+

Ans. D

Explanation:

Ans. is ‘d’ i.e., K+

Fluid in inner ear

  • There are two main fluids in the inner ear : –

(i) Perilymph                  

(ii) Endolymph

Perilymph

  • It resembles ECF and is rich in Nu+ ions. It fills the space between bony and the membranous labyrinth, i.e., Scala vestibuli and scala tympani. It communicates with CSF through the aqueduct of Cochlea which opens into the scala tympani near the round window. Therefore It closely resembles CSF. It is formed by : –

i) It is a filterate of blood serum and is formed by capillaries of the spiral ligament.

ii) It is a direct continuation of CSF and reaches the labyrinth via aqueduct of cochlea.

Endolymph

It fills the entire membranous labyrinth including scala media (cochlear duct). It resembles intracellular fluid, being rich in IC ions. It is secreted by the secretory cells of the stria vascularis of the cochlea and by the dark cells (present in the utricle and near the ampullated ends of semicircular ducts).



Leave a Reply

%d bloggers like this:
Malcare WordPress Security