ENT Physiology

Question 1

lifespan of a taste bud?

Answer 1

10 days

new ones generated by basal cells

Question 2

4 locations of taste buds

Answer 2

tongue x 3 types (foliate, fungiform, vallate)
palate
epiglottis
pharynx

Question 3

taste buds signal via different nerves depending on where they are. what nerves for…

• anterior tongue
• posterior tonguye
• epiglottis
• pharynx

Answer 3

anterior = cn 7
posterior = CN 9 
epiglottis = cn 10
pharynx = cn 10

Question 4

what are the 5 types of taste?

Answer 4

salty
sweet
sour
bitter
umani - meats, amino acids

Question 5

what typically causes hypogeusia?

Answer 5

reduced taste

chemo + medications

Question 6

pathway of smell signals from nose to brain?

Answer 6

Cilia 
Receptors cells   
Afferent olfactory nerves Bulb  
Tract  
Temporal lobe
Olfactory areas.

Question 7

hyposmia can be an early sign of what degenerative disease?

Answer 7

Parkinsons

Question 8

2 main functions of Eustachian tube

Answer 8

1. equalise pressure in the middle ear

2. drain mucus from middle ear

Question 9

how is an AP in the cochlear nerve stimulated?

Answer 9

stapes base vibrates at OW

pressure waves in the perilymph

hair cells in the cochlea are moved which stimulates APs in the cochlear nerve

Question 10

what is the organ of corti?

Answer 10

receptor organ for hearing, in the cochlea

on top of basilar membrane, made of epithelial cells

Question 11

what is the spiral lamina?

Answer 11

thin plate of bone that divides the cochlea in to scala tympani / scala vestibuli + cochlear duct

Question 12

what holds the cochlear duct in place?

Answer 12

the spiral ligament

Question 13

what is inside the scala media (cochlear duct) ?

ion characteristics?

Answer 13

ENDOLYMPH

low Na
high K

Question 14

what is inside the scala tympani + vestibuli

ion charactteristics?

Answer 14

PERILYMPH

high Na
low K

Question 15

what happens to ions when the organ of corti is stimulated?

Answer 15

Na INFLUX = depolarisation

Question 16

the pathway from cochlea to brain follows the letters C.O.L.I - what do they stand for?

Answer 16

C for cochlear nucleus
O for superior Olivary complex
L for lateral lemniscus
I for inferior colliculus

Question 17

where do sound signals get processed in the brain? what side?

Answer 17

LEFT

posterior superior temporal gyrus

Question 18

what can a foetus
> hear
> responds to voices etc

Answer 18

hear at 18 weeks

respond at 26 weeks

Question 19

what nerve supplies specifically the posterior semi-circular canal + the saccule?

Answer 19

the inferior vestibular nerve

other 2 SCCs and the utricles = superior V nerve

Question 20

when does depolarisation occur in the vestibular apparatus (balance) ?

Answer 20

1. head movement
2. gelaninous mass around the stereocilia gets moved
3. it moves the sterocilia hairs

4 = DEPOLARISATION OCCURS when the stereocilia hairs are bent TOWARDS the KINOCILIUM (longest hair)

Question 21

when does HYPERpolarisation occur in the vestibular apparatus?

Answer 21

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

Question 22

what structure in Vestibular apparatus accounts for angular movement change?

Answer 22

Semi circular canals

Question 23

what structure in vestibular apparatus accounts for horizontal movement change?

Answer 23

utricle

Question 24

hat structure in vestibular apparatus accounts for verticle movement change?

Answer 24

saccule

Question 25

what is the vestibular ocular reflex?

Answer 25

system that allows body movement + field of vision to be coordinated to stay balanced

Question 26

what is vestibular nystagmus caused by ?

Answer 26

damage to the V.O.R

Question 27

what is oscillopsia and what is it caused by?

Answer 27

visual disturbances caused by having no vestibular imput to the V.O.R

people get jumpy / rapid moving / blurry vision.