Healthy Ear
Inner Hair Cell
Inner hair cells are located in the cochlea and translate the sound signal into an electrical signal that is sent to the brain. They have stereocilia which when defected by sound allow potassium into the cells which depolarizes and activates them.
Inner Ear
The cochlea is the organ in the ear where inner hair cells reside. The base of the cochlea detects high pitch sounds while the apex detects low frequency sounds. It is also connected to the semicircular canals which detect acceleration and regulate balance.
Middle Ear
The middle ear begins with the eardrum which vibrates when hit with sound. This signal is then transferred through the bones of the ear (hammer, anvil, and stirrup) to the cochlea.
Diseased Ear
Noise-Induced Hearing Loss
Noise-induced hearing loss (NIHL) is loss of inner hair cells due to overactivation by loud noises.
Motion Sickness
The semicircular canals detect acceleration and motion, which when activated can induce nausea in certain individuals. This can lead to feeling dizzy and the urge to vomit.
Ruptured Ear Drum
A ruptured ear drum is when the ear drum membrane is compromised. One of the most common causes is a bacteria ear infection. Loss of ear drum integrity causes hearing impairment/loss.
Ear Treatment
NIHL -> Inner Hair Cell
Noise-induced hearing loss results in the permanent loss of inner hair cells. Because they cannot be replaced, the only treatment is the use of hearing aids.
Motion Sickness -> Cochlea
Motion sickness is one of the vomiting pathways in the brain and is activated by the semicircular canals which regulate balance. This signal is mediated by histamine and acetylcholine and can be treated with promethazine, which is a histamine and muscarinic receptor antagonist.
Ruptured Ear Drum -> Middle Ear
One of the common causes of a ruptured ear drum is a bacterial ear infection. This can be treated with ear drops containing the antibiotic ofloxacin, which causes bacteria DNA damage and death.
