TASTE/SMELL PT 2 Flashcards
describe olfacton threshold
low threshold, only a few molecules need to be present
does adaption happen quick
yes
describe olfactory receptors adaption
adapt by 50% in the first second or so and more slowly thereafter
describe complete adaption to certain strong odors
occurs in about 1 minute after exposure
what are the olfactory areas in the brain
hippocampus, amyglada, orbital frontal cortex, thalamus
wha are taste buds
Sensory receptors for taste
where are taste buds located
Located on tongue, cheeks, soft palate, pharynx, epiglottis
Most on tongue (~10,000)
what are papillae and what do they give the tongue
visible, peglike structures
Give tongue an abrasive feel
what does each taste bud consist of
50 – 100 epithelial cells of two major types
what are the two major types of epithelial cells that taste buds consist of
Gustatory epithelial cells; Basal epithelial cells
describe size of taste buds
microscopic
describe basal epithelial cells
Act as stem cells → dividing and differentiating into new gustatory epithelial cells
what are gustatory epithelial cells
taste cells; spindle-shaped chemoreceptors
where does the peripheral end of the gustatory epithelial cell terminate
terminates at gustatory (taste) pore with fine hair filaments, i.e. gustatory hairs
what do microvilli do at termination site
Microvilli project through taste pore into saliva
what are microvilli subject to
Subject to friction and frequently burned → Replaced every 7–10days
what do dendrites in each taste bud do
take signal from receptor cell to the brain
what are the five major classes of taste
sweet, sour, salty, bitter, umami
describe sour
acids (H+)
describe sweet
elicited by organics (sugars/salts)
describe salty
inorganic salts (metal ions/NaCl)
describe bitter
alkaloids (caffeine/nicotine)
describe umami
amino acids (glutamate/aspartate)
what are other tastes, like chocolate and coffee, created by
combinations of these five & accompanying olfactory sensations
how do cravings and taste preferences happen
Likes and dislikes have homeostatic value » Craving: may be indication of body’s need
how can taste sensations be protective
Can be protective
!! Intense dislike for extreme sour/bitterness warns of spoilage
!! Many natural poisons and spoiled foods are bitter
what must happen for a chemical to be tasted
Must dissolve in saliva, diffuse into taste pore
and contact the gustatory hairs
what induces depolarization
Binding of a chemical to gustatory cell
how are different guastory cells different
Different gustatory cells have different thresholds for activation (bitter receptors detect minute amounts)
what happens after neurotransmitter binds to associated afferent fiber (dendrite)
Triggers dendrite graded potential
→ Moves information to the 1st order neurons
how long does it take receptors to partially and fully adapt
Receptors partially adapt in 3-5s, completely adapt in 1-5min
describe chemical depolarization of salty taste
Na+ influx through Na+ channels
describe chemical depolarization of sour taste
H+ blockade of K+ channels
→ Allows cations to enter
describe chemical depolarization of bitter/sweet/umami
Receptor coupled w/ GPCR which leads to opening cation
whats the vagus nerve (X)
just need to know vagues nerve correlates with PNS because
stimulated witth taste
pretty much every sensosyr neuron w thalamus
where is the sweet taste on tongue
tip
where is salty and sour taste on tongue
sides
where is the bitter taste on tongue
back
where is the umami taste on tongue
pharynx
but do tastes stilll come from all areas
yes
what receptors does the mouth have
thermo-, mechano-, and nociceptors
what can enhance or detract from food taste
Temperature, texture, pain (spice
how much of taste is smell
80%
whats Dysosmia
distorted sense of smell
whats Anosmias
absence of smell
whats hyposmia
impaired sense of smell
what causes damage to olfactory epithelium and is it permanent
Inhalation of toxic fumes
Physical injury to interior of nose
Some nasal sprays
usually temporary but can be permanent
whats Dysgeusia
distorted sense of taste
whats ageusia
absence of taste
whats hypogeusia
decreased sensitivty
whats hypergeusia
increased senstibty
what are the four kinds of papilale
fungiform, foliate, circumvallate, filiform
