ENT Physiology Flashcards
lifespan of a taste bud?
10 days
new ones generated by basal cells
4 locations of taste buds
tongue x 3 types (foliate, fungiform, vallate)
palate
epiglottis
pharynx
taste buds signal via different nerves depending on where they are. what nerves for…
- anterior tongue
- posterior tonguye
- epiglottis
- pharynx
anterior = cn 7 posterior = CN 9 epiglottis = cn 10 pharynx = cn 10
what are the 5 types of taste?
salty sweet sour bitter umani - meats, amino acids
what typically causes hypogeusia?
reduced taste
chemo + medications
pathway of smell signals from nose to brain?
Cilia Receptors cells Afferent olfactory nerves Bulb Tract Temporal lobe Olfactory areas.
hyposmia can be an early sign of what degenerative disease?
Parkinsons
2 main functions of Eustachian tube
- equalise pressure in the middle ear
2. drain mucus from middle ear
how is an AP in the cochlear nerve stimulated?
stapes base vibrates at OW
pressure waves in the perilymph
hair cells in the cochlea are moved which stimulates APs in the cochlear nerve
what is the organ of corti?
receptor organ for hearing, in the cochlea
on top of basilar membrane, made of epithelial cells
what is the spiral lamina?
thin plate of bone that divides the cochlea in to scala tympani / scala vestibuli + cochlear duct
what holds the cochlear duct in place?
the spiral ligament
what is inside the scala media (cochlear duct) ?
ion characteristics?
ENDOLYMPH
low Na
high K
what is inside the scala tympani + vestibuli
ion charactteristics?
PERILYMPH
high Na
low K
what happens to ions when the organ of corti is stimulated?
Na INFLUX = depolarisation
the pathway from cochlea to brain follows the letters C.O.L.I - what do they stand for?
C for cochlear nucleus
O for superior Olivary complex
L for lateral lemniscus
I for inferior colliculus
where do sound signals get processed in the brain? what side?
LEFT
posterior superior temporal gyrus
what can a foetus
> hear
> responds to voices etc
hear at 18 weeks
respond at 26 weeks
what nerve supplies specifically the posterior semi-circular canal + the saccule?
the inferior vestibular nerve
other 2 SCCs and the utricles = superior V nerve
when does depolarisation occur in the vestibular apparatus (balance) ?
- head movement
- gelaninous mass around the stereocilia gets moved
- it moves the sterocilia hairs
4 = DEPOLARISATION OCCURS when the stereocilia hairs are bent TOWARDS the KINOCILIUM (longest hair)
when does HYPERpolarisation occur in the vestibular apparatus?
depolarisation is due to movement in one direction…
and the area that accounts for the other direction gets HYPERPOLARISED so channels close + no signal produced
what structure in Vestibular apparatus accounts for angular movement change?
Semi circular canals
what structure in vestibular apparatus accounts for horizontal movement change?
utricle
hat structure in vestibular apparatus accounts for verticle movement change?
saccule
