CNS/sensory 6 - vestibular, olfactory, gustatory Flashcards
where are vestibular organs
located in inner ear
what are vestibular organs
all fluid filled compartments
transduction process same as cochlea
tells you how head moves through space
describe utricle and saccule
linear acceleration
forwards/backwards, up/down
utricle = horizontal
saccule = vertical
describe semicircular canals
encode angular acceleration
as head rotates up and down
describe vestibular ocular reflex
balance, helps you understand how head moves but also controls eyes
when wiggle head = activate reflex
as move head in one direction = vestibular signals that detect head acceleration (angular movement) cause your eyes to move in opposite direction = reflex
keeps gaze (what looking at) constant
how does transduction occur for vestibular
tip links gate ion channels
only difference = way stereocilia moved
describe organization of semicircular canals
ampula = gets big, in fluid structures
cupula = mass of gelatine like membrane, can bend
stereocilia = inside cupula
diff angles encode rotation
describe process of semicircular canals
cupula moves since head moves
fluid has inertia so does not move right away = exerts force on cupula and causes it to bend stereocilia = pulls on tiplinks and ion channels open or close
describe motion sickness
vestibular system being activated but conflicts with visual system that says we are not moving
describe dizziness
spinning in chair = fluid has inertia and lags but then catches up and then you stop and fluid exerts force on cupula and bends stereocilia
so brain says im moving but you just stopped = vebstibualr system still thinks head is moving
what do utricle and saccule detect
linear acceleration
similar transduction
fluid filled
describe utricle and saccule process
Epithelium layer of hair cells sticks up stereocilia into otoliths (jelly mass with rock)
= float in fluid but when acceleration = otoliths have inertia and do not accelerate right away
once maintain constant speed = otoliths catch up and back to neutral, stereocilia not bent
describe what happens alcohol - utricle and saccule
feel dizzy at end of night bc alc changes specific gravuty of fluid in inner ear and otoliths no longer naturally buoyant and starts to float = gives sensation of movement
describe taste - gustation
papillae has taste buds, inside grooves of papillae
Saliva dissolves molecules and goes to taste bud then binds inside taste pore (lined with taste cells - bind chemically to receptors and initiates cells)
taste afferent = active and sends ap to brain
how many taste buds do we have
10,000 taste buds
but can only distinguish a few tastes
describe taste transduction
each taste mediated slightly diff transduction process
describe umami transduction
umami –> glutamate receptors on tongue –> g protein cascade = gives umami flavour, flavour enhancement like msg
describe salty transduction
due to sodium ions of food in mouth flowing through iron channels selective for sodium
describe sour transduction
high acid
extra protons interact with channels = block or enhance them
source can block sodium - tastes interact
describe bitter transduction
very complex
many substances = developed as protection mechanism
blocks ion channels (potassium)
or
specialized bitter receptors that bind molecules that taste bitter and then triggers various g protein cascades = open/close/modify ion channels
many transduction processes
describe sweet transduction
sugar binds to specialized receptors on taste cell that then active g protein cascade and open /close ion channels
Describe central taste pathways
afferent activated and travels to cns by cranial nerves –> synapse in medulla –> thalamus –> projects into gustatory complex to ipsilateral gustatory cortex (does not cross midline), perception of taste happens
what is spicy
pain or heat response
not taste
describe olfaction
odorant molecules enter nose and nasal cavity
has olfactory epithelium
binds to olfactory receptor cells that have cilia that line top of nasal cavity - sit in layer of mucous, ordorant molecules dissolve in mucous and bind chemically with receptors in cilia
Olfactory receptor cells (send axons across bone) –> olfactory nerve –> olfactory bulb (has circuitry, part of cns) –> axons from olfactory tract foes to other parts of brain
Describe olfaction signal transduction
1 - odorant binding to oderant receptors the (weak or strongly)
2 - g protein cascade activation (motors, opens ion channels)
(each taste cell, expresses unique set of odorant receptors - selective to unique chemical composition of odors)
3 - open ion channels
how many oderant receptors and describe sensitivity
1000 oderant receptors
Sensitive to 10000 diff odors = satisfaction when eating food mostly comes from smell not taste
some molecules bind some receptors tightly and others less = sets up population code, even tho only 1000 receptors - odorant molecules bind more than on type of receptor
describe central olfactory pathways
sent to olfactory bulb = does processing and sends via olfactory tract directly into limbic system
odors and smells can trigger emotions
direct link between olfaction emotions and memory
what are emotional responses mediated by
involved in emotions and memory
how we score and rate sensory experiences
tend to remember experiences that produce high emotional response - good or bad
describe perfumes
whole industry dedicated to limbic system
how you smell = affects limbic systems of other ppl
