phys of olfactory sys

Question 1

what is anosmia?

Answer 1

lack of sense smell

Question 2

what is aguesa?

Answer 2

lack of sense of taste

Question 3

what are tastants?

Answer 3

chemical compounds that bind taste receptors and impact primaty flavor

Question 4

what are odorants?

Answer 4

chemical compounds that bind odorant receptors

Question 5

what are tastebuds?

Answer 5

specialized epithelial cells

apical and basal domains

Question 6

how is chemosensory tranduction done in taste buds

Answer 6

started in apical domain, electrical signals generated in basal domain via graded recepors

release NT

Question 7

where are taste receptor proteins concentrated?

Answer 7

concentrated in microvilli that emerge from apical surface

Question 8

explain how receptor potentials are produced in taste bud cells?

what can it cause

Answer 8

voltage regulated ion channels, secondary messenger channels, esp TRP

intracellular calcium release facilitates synaptic vesicle fusion

NT released onto basal synapse with local afferents

causes receptor potential

if large enoguh, can cause action potential

Question 9

what are olfactory cells, and what do they release?

Answer 9

bipolar neurons that release glutamate as primary NT

Question 10

where do odorants bind and what do they activate? name the steps

Answer 10

receptor molecules in cilia

activate specific G protein

activate adenylate cyclase

activates cAMP

cation sensitive channel opens and influxes Na and Ca

depolarization, opening of Ca and Cl- cannels

more depolarization, generate receptor potential

Question 11

what reduces receptor potential magnitude for olfaction?

Answer 11

drop in cAMP due to enzymatic breakdown

Calcium binds to calmodulin, reducing affinity for channel to cAMP

odorant receptor can be phosphorylated

Question 12

what happens if odorant receptor gets phosphorylated

Answer 12

modifies sensitifvity to odors

get used to smell

Question 13

how foes the olfactory cascade work?

Answer 13

Golf stimulates adenylyl cyclase

increasing cAMP

opens cyclic nuleotide gated channels

cation influx

depolarization of membrane

Question 14

what happens when odorant stimulation persists?

Answer 14

sensitivity of CNGC to cAMP decreases, cation influx reduced

or

inactivated by receptor phosphorylation
(get used to it)

Question 15

what cant you taste your food if you have a cold?

Answer 15

thickened mucus blocks odorants from binding to odorant receptors

“hyperosmia”

Question 16

sweet foods signal what?

Answer 16

presence of carbs

Question 17

salty foods signal what

Answer 17

intake of Na, which maintains bodys water balance and blood circulation

Question 18

umami signals what?

Answer 18

reflect foods protein content due to glutamate

Question 19

sour signals what?

Answer 19

dietary acids

avoid ingesting this food, might be bad

Question 20

bitter taste signals what?

Answer 20

innately bad mkay

guards against consuming poisons

bitter GPCRs bind ligand very tightly, taste bitter at low concentrations

but you can overcome taste responses

Question 21

what happens to olfaction as you age?

Answer 21

sensitivity decreases, can cause you to eat more salt

hypertension risk

Question 22

what tastes do newborns respond to? why is this relevant

Answer 22

dilute, sweet tastes

sweets can act as analgesics for newborns, has calming effect

Question 23

where does analgesia from sweet tastes come from in newborns?

Answer 23

general brain arousal might be suppressed

most widely accepted mechanism is beta endorphin release, activating endogenous opiois system

PAG and raphe nucleus are immature still

Question 24

can we link levels of sweetness to caloric value?

Answer 24

no, because of artificial sweeteners

long term effects are unknown

Question 25

how can bitter taste be masked? at what level?

Answer 25

sodium salts: suppress bitter at level of bitter receptor

sugars: cognitive level

energy drinks and alcohol are stopped this way!

Question 26

how does nucleus of the solitary tract process food?

Answer 26

receives multiple sensory inputs from vagus nerve

relays this info to viscera

reflex circuits that form basis for salivary secretions, mimetic responses, swallowing

Question 27

how does central posterior medial nucleus of thalamus process food?

Answer 27

relay station for food perception

discriminative aspects of food!

Question 28

how does gustatory cortex process food?

Answer 28

consists of insular taste cortex

operculum

post central gyrus

Question 29

how do hypothalamus and amygdala process food?

Answer 29

emotion context of eating

memories of eating for amygdala

integrate homeostatic mechanisms such as hunger

interplay between eating and calming effects of food

Question 30

how do orbitofrontal cortex process food?

Answer 30

integrate visual, somatosensory, olfaction, gustatory stimuli to appreciate food

Question 31

what cells make up olfactory mucosa and bulb? what do they do

Answer 31

granular cells which increase specificity by releasing gaba

mitral and olfactory cells which project into olfactory tract

periglomerular cells which increase specificity, release gaba

olfactory neurons which synapse on glomeruli and release glutamate

Question 32

how does anterior olfactory nucleus process olfaction?

Answer 32

relay station for ipsi and contralateral cortices

Question 33

how does piriform cortex and lateral hypothalamus process olfaction?

Answer 33

control apetite and how olfactory input influences appetite and hunger

Question 34

how does anterior cortical amygdaloid nucleus process olfaction?

Answer 34

emotional learning, olfactory fear conditioning

Question 35

how does periamygdaloid cortex process olfaction?

Answer 35

integrate emotional aspect of food as elicited by odor

Question 36

how does entorhinal cortex and hippocampus process olfaction?

Answer 36

memeory formation and how olfactory input facilitites memory and recall

connections within limbic and entorhinal cortex responsible for memory upon smelling odor!!

Question 37

how is parkinsons relatd to the olfactory system?

Answer 37

neurons of olfactory among first to experience pathology , even before motor deficit

used as a biomarker for neurological disease!