Hearing, Taste, and Smell Flashcards
What is the auricle? its function?
the visible part of the ear, it collects and amplifies sound
What is the external auditory meatus? function?
the auditory canal. it is an air filled space that transmits sound to tympanic membrane
What is the tympanic membrane? function?
the ear drum, it converts sound waves to mechanical vibrations
How are the mechanical vibrations transmitted to the oval window into the inner ear?
via the tympanic ossicles
What are the 3 tympanic ossicles?
-mallus, incus, stapes
What is the function of the auditory tube (eustachian tube)
connect middle ear to nasopharynx. it is normally collapsed but will open to equalize pressure
What are the two skeletal muscles associated with the ossicles?
-tensor tympani
-stapedius
What are the 3 components that make up the boney labyrinth of the inner ear?
-Cochlea
-Vestibule
-Semicircular canals
What is the outer boney labyrinth filled with
perilymph
What is the inner membranous labyrinth filled with?
endolymph
What are the regions of the inner membranous labyrinth that are specialized sensory regions?
-Cristae amplularis (SC canals)
-Maculae (saccule and utricle)
-Spiral organ of corti (Cochlea)
How do the sensory hair cells of the specialized sensory regions transduce signal?
-mechanical displacement of stereocilia
-depolarization
-opening of K channels, high k in endolymph favors movement into cell
-voltage gated ca channels open
-glutamate released
What is the modiolus?
the bony projection that runs through the middle of the cochlear spiral
what creates endolymph?
the lining cells of the membranous labyrinth (stria vasculari)
Explain how auditory signal is transduced once it is already in the middle ear
The mechanical vibration created by the ossicles travel along the basalar membrane, this causes the sensory hair cell stereocilia to move ultimately causing the release of glutamate onto the dendrites of the bipolar neurons of the cochlear nerve, the central axons then come together in cochlear nerve and then leave
What are the sensory regions of the saccule and utricle?
maculae saccili and maculae utriculi
What portion(s) of the inner ear are responsible for vestibular signal transduction?
the vestibule (saccule and utricle) and the semicircular canals
Explain signal transduction of vestibular signal, rotational movement
similar to auditory but the stereocilia of the sensory hair cells are embedded in the cupula, so once the head moves the, the endolymph moves causing the stereocilia to move, which causes firing and then the vestibular nerve endings around the hair cells are stimulated
What are the 5 tastes detected?
salty, sweet, sour, umami, bitter
Where are taste buds located?
gustatory lingual papilla, soft palate, epiglottis, and pharynx
Describe signal transduction for salty tastes
-Na from food enters na channel, depolarization, influx of Ca releases NT
Describe signal transduction for sour tastes
H+ blocks K channel, k can’t leave, depolarization of cell, influx of ca, NT released
Describe signal transduction for bitter tastes
bitter substance binds, conformational change, g protein cascade to activate phospholipase C, IP3 generated, IP3 causes Ca to be released from intracellular stores, NT released
Describe signal transduction for sweet tastes
sweet binds, conformational change, g protein cascade to activate adenylate cyclase, catalyzes conversion of ATP to cAMP, cAMP activates protein kinase, closes K channel, depolarization, Ca influx, NT release
