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Lecture

PSYC 367 Lecture Notes - Taste Bud, Taste Receptor, Afferent Nerve Fiber


Department
Psychology
Course Code
PSYC 367
Professor
James Hyman

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I. Taste
1. Taste/Gustatory anatomy:
Tongue map: different section of the tongue responsible for different taste. This is
Wrong! Instead, we have receptors for all different tastes located all over our
tongue.
The Tongue:
1) Fungiform Papillae (cluster of taste buds.
Three main types): mainly margins and tip of tongue,
mushroom shaped (2nd), contain only one bud??or six?
2) Foliate Papillae: back sides of the tongue, look
like a series of folds, each contains many different
buds
3) Circumvallate Papillae: flat hills with circular
trench, back of the tongue, each contain many
different buds (3rd)
4) Filiform Papillae: No taste function, front of
tongue (1st), contain only one bud??
Taste Buds 味蕾: a group of different cells; each bud contains 50 -150 cells; taste
bud cells made up of active taste cells, basal cells, and other cells
1) Basal Cells: young taste cells that haven’t matured
(the small round cells at the bottom)
2) Taste Receptor Cells: modified skin cells; just like skin
cells, they have a limited life span-- individual taste cell will
last just a few days. When they die they got replaced by basil
cells that got matured.
3) Other cells: responsive to other stimuli besides
chemical stimuli, that contribute to our sensation taste, such
as temperature, pressure, and pain.
4) Microvilli: projections from the receptor cell that will
open up into the surface of the tongue and get exposed to
the saliva; they are extensions of the cell membrane.
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2. Physiology of the Gustatory System:
How Taste Cells Transduce Taste into Neural Signal:
Transduction: generic cell-- there’s microvilli, nucleus, but it’s not a
neuron, so no action potentials, but will release neurotransmitters to an
afferent nerve, and the release will be provoked by an influx of calcium;
5 pure tastes: defined by the 5 tastes receptors; the input source must be
water soluble or else we won’t taste it
Through Ion Channels (no receptor taken place):
1) Salt: something salty is broke down into Na+ and make it way into the
sodium (Na+) channels at the microvilli of a taste receptor cell, and into
our taste cell depolarization of our taste cell (when efficiently
depolarized) opening of calcium (Ca2+) channelsCa2+ influx
neurotransmitter release increase firing in the afferent nerve who
carry the signal to the brain
2) Sour: sour substance broke down into hydrogen atoms (H+), taking in
through the ion channelH+ goes in, K+(Potassium) goes out
depolarization …(same as above)
True Chemical receptor, lock-and-key mechanism:
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