Question

10.19 Three spaces in the cochlea and the type of fluid that fills each one
10.20 Mechanism of hearing at the inner hair cell level- what happens after hair cell cilia are bent?
10.21 Sensorineural deafness/ conduction deafness: Definition and causes/ Presbycusis
10.22 Mechanism of glaucoma

Answer 1

10.19) Cochlea is the inner portion of the ear. it consist of three fluid filled spaces they are

• Vestibular duct - which is filled with perilymph
• Lymphic duct - which also fill perilymph
• Cochlear duct - contain endolymph

Perilymph and endolymph are intra cellular fluids . in which the former is rich in sodium ions and the latter is rich in potassium ions.

10.20) Mechanism of hearing at the inner cells. I will explain it step by step:

• The vibration form the outer and the middle ear pass into the inner ear.
• In cochlea there are tiny hair cells , when this moves up and down the stereocilia hit the overlying structure and bend.
• when it bend , the pore like channels present at the tip of the stereocilia open up
• at this time the chemical move towards the cells and create an electric signal
• these signals are carried by the auditory nerves to the brain
• which is then convert to the sound that we can recognize and understand.

10.21)

Sensorineural deafness  : is a type hearing loss caused by damage to the inner ear or the nerve from the ear to the brain. There are two type of sensorineural deafness and the causes vary accordingly

*Congenital ( occur during pregnancy )

• prematurity
• maternal diabetes
• lack of oxygen during birth
• rubella ( passed from mother to child )

* Acquired ( occur after birth)

• Aging
• Noise ( when exposed to explosion)
• Disease/ Infection ( viral, measles, meningitis, mumps)
• Tumors
• Head or Acoustic trauma

Presbycusis: it is a very common type of senorineural hearing loss caused by the natural ageing of the auditory system.

Causes

• Medication ( mainly ototoxic medication)
• people subjected to blaring noise

10.22) Mechanism of glaucoma :

• it is mainly caused due to high blood pressure
• when pressure increases the damage the optic nerve
• which fail to carry visual information to the brain
• thus resulting in glaucoma.