Lecture 15 Flashcards
more receptors in taste buds means
greater acuity and sensitivity
what are the five kinds of taste reeceptors
salty, sour, sweet, bitter, umami
three different kinds of papillae
circumvallate papillae in back of tongue
foliate papillae in middle
fungiform papillae in front
where are taste buds and how do they perceive tastes
in between papillae in the grooves
little cilia projections outside cell swish in the molecules that are in the fluid
when molecules come in they act directly on individual receptors
causes action potentials that go to brain
which of the five taste receptors act directly on ion channels and which activate second messengers
salty and sour act directly on ion channels
sweet, bitter, and umami activate second messengers
the process for salt receptors
high levels of NaCl, goes in through Na+ channel, increases Na+ in cell, causes depolarization so voltage gated Ca2+ opens into cell and causes a release of NT into synapse and sends AP to brain
the process for sour receptors
High H+ inhibits K+, causes them to close so level of K+ in cell builds up, causes depolarization, Ca2+ opens into cell and causes a release of NT into synapse and sends AP to brain
the process for umami receptors
T1R1 and T1R3 stimulate G proteins which work through a number of signal transduction pathways (including 2nd messengers cAMP) act on endoplasmic reticulum which causes an internal release of Ca2+, releases NT, activation of axons
the process for bitter and sweet
same as umami but for
bitter- T2R receptor and G protein coupled receptors
sweet- T1R2 AND T1R3
what does flavor depend on and examples
gustatory and olfactory (taste and smell)
ex: durian smells terrible but tastes like mango
cilantro some people think tastes like soap
how does brain decode taste
data exist that supports both labeled lines and patterned coding theories
What is the pathway for taste after receptors go to axon
taste receptors go from tongue to one of the three nerves (vagus nerve, glossopharyngeal nerve, or facial nerve) to the brainstem, which sends axons to thalamus then to gustatory cortex (anterior insula and frontal operculum)
which brain areas would be activated if remembering a disgusting food experience
hippocampus for conscious experience and insula because taste areas of the brain copy the original taste experience, re experience it
which brain areas would become activated if imagining traveling and being served foods very different from what is culturally appropriate, ex being vegan and served a chicken head
attention in brain areas involved in experiential memories and attention of same areas that would’ve been active by actually doing it (insula of cortex)
pathway for olfactory system (smell)
smell goes in through nose, receptor cells are embedded on roof of nose which have villa (hairs) on them which swish smells up against the receptors, the odorants (molecules) get trapped in fluid (snot) and influence endings on the receptor cells, the receptor cells have axons that go to the olfactory bulb into distinct clumps of cells called glomerulus’s (each glomerulus have their own axons that go to different parts of cortex)
mitral cells in the glomerulus collect inputs and send them out of the olfactory bulb
olfactory receptor cells and neurons
about 6 million receptor cells in humans (350 different kinds of receptors) 100 million in dogs (1000)
keep being replaced throughout lifetime
metobatropic receptors
use second messengers (cAMP) to open Na+, Cl-, and Ca2+ channels and depolarize the receptor cell
vomeronasal organ (VNO) system
separate the olfactory system found in animals with wet noses
goes from vomeronasal organ to vomeronasal nerves to accessory olfactory bulb (detection of phermones)
pheromones
used for mating and identification
oil based so persist for long time
