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Chemical senses
Nuero
24
Microbiology
Graduate
09/28/2009

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Cards

Term
Tip of tongue tastes
Definition
Sweet
Term
Back of tongue tastes
Definition
Bitter
Term
Sides of the tongue tastes
Definition
Salty and sour
Term
Tastes buds
Definition
Multiple per papillae (bumps) ~5000 total
Term
Taste receptor cells
Definition
~50-150 per taste bud. Varying response profiles even within a single taste bud
Term
Amiloride
Definition
A potassium-sparing diuretic, first approved for use in 1967 (then known as MK 870), used in the management of hypertension and congestive heart failure.
Term
Salty taste channels
Definition
Specialized Na+ selective Channel.
Non voltage gated
Blocked by amiloride
Term
Stimulus= High external salt concentration such as chicken soup. What happens in the taste receptor pathway?
Definition
1) Na+ enters through amiloride channels(inward current).
2) Depolarization Amplified by voltage gated Na+ channels (receptor potential, no action potential)
3) Ca2+ enters through Ca2+ voltage gated channels
4)Synaptic vesicle fusion/ Transmitter release
Term
Sour taste
Definition
Sour = acidity = low pH = high concentration of H+ ions. Protons = Tastant
Term
Sour Taste Channels
Definition
H+ enters Amiloride sensitive Na+ channels which causes depolarization. H+ also blocks K+ channels which furthers depolarization. (most likely more unknown mechanisms as well)
Term
Bitter, Sweet, and Umami
Definition
All use G protein coupled GPCR receptor pathways.
Term
Families of Taste receptor Genes
Definition
T1r and T2R
Term
Bitter Taste
Definition
~30 different T2R receptors, specialized for poisons.
Term
Sweet
Definition
2 particular T1r receptors (T1R2 and T1R3)
Term
Umami
Definition
Detects amino acids (savory). Two particular T1R receptors T1R1 & T1R3
Term
Cranial nerves involved in Taste
Definition
VII (facial) IX (glosopharyngeal) and X (Vagus)
Term
Pathway Taste travels from tongue to brain
Definition
Tongue -> Medula -> Thalmus -> Cortex
Tongue -> gustatory nucleus -> VPM -> Gustatory nucleus
Term
ageusia
Definition
Loss of Taste perception. Could be caused by lesions to Gustatory Thalmus, VPM or Gustatory cortex
Term
Individual receptor cells are
Definition
Diverse
-Different receptor cells respond differently to the same stimulus.
Broadly tuned
-Receptor cells respond to more than one type of stimulus (eg. both salty and sour)
Term
Complex flavors such as Banana are coded by
Definition
Patterns of activation across the population of receptors
Term
Olfactory receptor cells
Definition
True nuerons, each has its own axon
Regularly replaced every 4-6 weeks
Humans~12 million Olfactory receptors
Cranial Nerve I = Axon of all the olfactory receptor cells.
Term
Odorant Receptor Proteins (ORP)
Definition
More than 100 types of Odorant receptor proteins
Each receptor cell typically expresses only one ORP
G protein coupled receptor pathway
Generate action potentials
Diverse broadly Tuned
Term
Olfactory glomeruli
Definition
~2000 on each bulb
Specific mapping
Each glomerus receives input from a large region of the olfactory epithelium
receives input only from receptor cells expressing a particular odorant receptor gene
Term
l
Definition
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