Karius Special Senses: Taste Flashcards
Relation of smell and taste
interact to produce flavor of food
change with age
Where are odorant receptor located
cilia that protrude into mucus layer
What type of receptor are odorant receptors
G protein coupled receptors– Gs
activated adenylyl cyclase
What if odorant persists for more than a few minutes
sensitivity of channel to cAMP is reduced
reduce Na and Ca entry
Olfactory neuron and odorant receptor relationship
olfactory neuron expresses the same odorant receptor on ALL of it’s cilia
Location dependency for odorant receptors
different odorant receptors are localized to different parts of olfactory epithelium
Advantage to the distributed localization seen
if one area doesn’t work then i just don’t smell it– i dont abolish the sense of smell
Odorant effect on odorant receptors
each odorant activated different combinations of odorant receptors to produce characteristic odor
Odorant concentration
changes the perceived smell
High concentrations of odorant
odorant binds with lower affinity
Trace amine associated receptors
produces physiologic/endocrine responses to pheromones (in urine)
Where do axons of olfactory neurons pass through
cribriform plate and synapse on the neurons on the olfactory bulb
Granule cell layer
interact with tufted cells
Mitral cell layer
olfactory neuron synapse here
long end goes to glomeruli and other becomes tract
Location of external plexiform layer
olfactory bulb
Glomerular layer
collection of neurons, synapse
Granule cell
NOT activated by olfactory neuron
release GABA and synapse with mitral and tufted cells
Where are tufted cells found
external plexiform later
Tufted cells
Send info to the brain
Three kinds of post-synaptic neurons
mitral cell, tufted cell, periglomerular cell
Mitral and Tufted cells
axons from these neurons will go to the olfactory cortex
Periglomerular cells
inhibit the activity from glomeruli (inhibit from getting to brain) – getting rid of other distractions so the strongest smell goes to the brain
release GABA
remain in olfactory bulb
What happens at the ipsilateral olfactory bulb
all axons expressing same odorant converge on a medial and lateral glomeruli
Neighboring olfactory glomeruli
associated with chemically similar odorants
Olfactory cortex
send all odorants to same place and then be selective
responsible for identifying odorants
sends input BACK to epithelium to help adapt to smell
Anterior olfactory nucleus
relay info to same side and contralateral side
how both sides of brain receive smell
Piriform cortex
located in anterior olfactory nucleus of olfactory cortex
important in control of appetite
Lateral entorhinal corex
located in anterior olfactory nucleus of olfactory cortex
Entorhinal cortex
projects to hippocampus
important in memory of smell and recall of smell
NEMO!!
Medial orbitofrontal cortex
used to identify the flavor of foods
Taste (gustation)
chemical sense that interacts closely with olfaction
Sour taste
hydrogen ion via hydrogen canal
Salty taste
produced when sodium or calcium ion enter the taste bud via sodium or calcium channel
Umani taste
metabotropic glutamate receptor via glutamate
Sweet taste and bitter taste
use second messenger system not directed related to metabotropic receptors
Gustatory input travel to brain
NTS –> thalamus –> Gustatory cortex and lateral hypothalamus
Gustatory cortex
basic taste and innate responses
ex. attract sweet tastes or aversion of bitter taste
Perception of flavor: Gustatory input
from gustatory cortex
Perception of flavor: Olfactory input
from olfactory cortex
Perception of flavor: Somatosensory input
from mouth
Perception of flavor from all 3 areas
send axons to lateral posterior orbitofrontal cortex to produce sensation of flavor and appreciation of food
Compare and contrast receptors for smell an taste
Taste we have 5
Olfactory Gs to help Na and Ca channels open
How each signal (taste and olfactry) is modified/interpreted
largely in olfactory bulb, all going through glomeruli from a similar odorant and purpose to get rid of distractors
Process of each (taste and olfaction) in its respective cortex
identify what odor is - Entorhinal cortex
send hypothalamus for appetite control and identify what you’re eating
Explain how a patient presenting with loss of taste may be experiencing olfaction loss
because odorants in the mouth that come from olfactory epithelium and is a big chunk of taste
Explain how and why olfaction strongly influences memory
How- Entorhinal cortex and how it goes to the hippocampus
Why- because olfaction is important in recognizing things
ex. dogs sniffing each other’s butts
