Ch 16: The chemical senses Flashcards
What is the difference between taste and flavour?
taste =molecules in mouth stimulate tongue
flav= what we experience via also olfaction
What are the basic taste qualities? (5)
salt sour sweet bitter umami
How are chemicals transduced on the tongue?
each taste bud = 10-100 taste cells
each taste cell has tips that protrude into taste pore
-microvilli of receptor cells project out of taste cells
-chemical hit receptor site thru the pore
-causes electric signal toward brain via diff neurons…
-sodium penetrates membrane of receptor depolarizing it
-sour substance contain H+, block ion channels
-other chems. form bonds w/molecules in membrane. cause chemical changes within cell
What are the gustatory neural pathways?
- chordates tympani (front and side)
- glossopharyngeal (back)
- vagus (mouth and throat)
- superficial petrosal (soft palate)
What factors affect gustatory threshold?
-certain regions more sensitive to certain tastes
-more sensitive @ room temp than cold/hot
-tasters/nontasters/supertasters
-some ppl can taste PTC (bitter) - super tasters don’t like bitter
-via # size and density of papillae
How do we perceive “hot” and “cool” tastes?
chemesthesis: sensation arise when compounds in food activate mechanisms for pain touch and thermal percepe
capsaicin: pepper chemical. binds to valillioid
-triggers heat signal/inflamation
-scoville units = heat measure
-alcohol produces cool sensation extracted from peppermint
How can olfactory stimuli be described, and categorized?
smell = molecule of volatile substances (give off vapours)
Aristotle = 4 basic categories of smell
odor prism: any odour combo of6 properties and exists somewhere on prism. prob = need more categories and sometimes doesn’t add up
What are two theories of olfaction?
- stereochemical theory: classify smells based on molecule shape
-shape fit to certain receptor site
-evidence via inability to perceive certain door
-but sometimes shape not correspond to smell - odor prism (see other card)
What structures are involved in olfaction? What is the transduction mechanism?
olfactory musosa: olfactory epithelium and mucous
-molecules picked up from olfactory binding proteins here
-bind to olfactory receptors on colic of olfactory receptor neurons
-open ion channels = depolarization
ENCODED COMBINORICALLY: diff smells encoded by certain combo of Ors
-each OR component for MANY smells
-like alphabet
What are the olfactory neural pathways?
-olfactory nerve - olfactory bulb
-ORN axons/dendrites of bulb form clusters called glomeruli (via chemotropic map)
path 1: olfactory cortex:conscious exp, temporal
(prirform)
path 2: 2nd olfactory cx (orbitofrontal)
What factors affect olfactory threshold and identification?
age
smoking
menstruation cycle
individual diffs
# of receptors
Describe some psychological effects of odourants.
aromacology: influence small on behaviour etc
aromatherapy: placebo only. diff scents = peacefulll woooodhfde
ilanool = mint, reverse stress effects in rats
cinnamon increase performance sport (maybe)
proust effect: smell associated with personal childhood memory. b/c odor centre v close to hippocampus and amygdala
pheromones: releasers = immediate, primers = long lasting. detected by veromensasal organ. musk in humans. NO TRUE ONE FOUND IN HUMANS ITS BS
tongue structure 16.3
filiform: whole tongue look rough
fungiform: mushrooms tip and sides
foliate: folds on back and sides
circumvallate: flat mounds
-AL EXCEPT FILLIFORM HAVE TASTE BUDS
sensory coding for gustation
- labeled lines (specificity)
-diff taste = diff fibre, intensity = fire rate
-but many substances = more than one taste - across fibre (population)
-no specialized receptors
-taste = population activity
-some tuned better to certain tastes than others
mouth nerves tranceduce to what paths…
nucleus of solitary tract in medulla…
-3 pathways
-thalamus path: conscious taste
-hypothal/amyg path: emotional component
