PHYS physiology of olfaction and gustation

Question 1

5 taste categories:
ATP - channel?
5-HT

Answer 1

ATP: PanX1 channel
    sweet
    umami
    bitter
5-HT
    sour
    salty

Question 2

ATP released from sweet umami bitter receptor cells stimulate

Answer 2

post-synaptic gustatory neurons
pre-synaptic salty/sour receptor cells to stimulate 5-HT
release
autocrine signaling

Question 3

5-HT released from salty/sour receptor cells stimulate

Answer 3

post-synaptic primary gustatory cells

Question 4

what evokes sour receptors

what happens when sour receptors are evoked

Answer 4

H+ ions

inhibits K channels from flooding additional positive charge into the cell –> depol.

Question 5

sweet, umami, bitter receptor pathway

Answer 5

GPCR (PLC/IP3 pathway) –> increased Ca –> TRPM5 (Na) –> depol –> release of ATP through panx1 –> NT release

Question 6

what GPCR does the umami pathway

Answer 6

mGluR4

Question 7

why does the bitter pathway have the highest affinity GPCR

Answer 7

POISON

Question 8

where do all taste tracts terminate

Answer 8

nucleus tractus solitarius (gustatory area)

Question 9

ascending taste pathway

Answer 9

–>nucleus tractus solitarius –> VPM –posterior limb of IC–> postcentral gyrus, frontal operculum, insular cortex

Question 10

which 3 cortical areas are referred to as the gustatory cortex

Answer 10

postcentral gyrus
frontal operculum
insular cortex

Question 11

what is responsible for integrating visual, somatosensory, olfaction and gustatory stimuli

Answer 11

orbitofrontal cortex

Question 12

what is responsible for the affective aspects of eating, emotional context to eating, and memories of eating

Answer 12

amygdala

Question 13

what is responsible for the integration of homeostatic mechanisms of eating (hunger)

Answer 13

hypothalamus

Question 14

olfactory g protein pathway

Answer 14

Golf –> cAMP –> opens cyclic nucleotide gated channels (CNGC) –> cation influx –> depol

Question 15

describe adaptation of smell

Answer 15

as odorant persists:
1) sensitivity of CNGC to cAMP decreases
or
2) inactivated by receptor phosphorylation

Question 16

what factors can affect how we percieve a smell

Answer 16

combination of odorant receptors activated

concentration of odorant

Question 17

inhibitory interneurons of the olfactory bulb

Answer 17

granular cells

paraglomerular cells

Question 18

f(x) anterior olfactory nucleus

Answer 18

???

relay station to ipsi- and contralateral cortices

Question 19

f(x) of piriform cortex –> lateral hypothalamus

Answer 19

control of appetite

olfactory input influences appetite and hunger

Question 20

f(x) of piriform cortex –> thalamus –> medial orbitofrontal cortex

Answer 20

integration of taste sight and smell

appreciation of the flavor of food

Question 21

f(x) of anterior cortical amygdaloid nucleus

Answer 21

emotional learning; olfactory fear conditioning

Question 22

f(x) of periamygdaloid cortex

Answer 22

integration of emotional aspect elicited by odor

Question 23

f(x) of entorhinal cortex –> hippocampus

Answer 23

important in memory formation

olfactory input facilitates both memory formation and recall

Question 24

what does perception of flavor require

Answer 24

gustatory input from gustatory cortex
olfactory input from olfactory cortex (esp piriform cortex)
somatosensory info from the mouth

medial orbitofrontal cortex