chapter 16: chemical senses Flashcards
define anosmia
loss of sense of taste and smell
name the three components of taste and smell
- taste
- olfaction
- flavour (combination of taste and smell)
what is one property that distinguishes the chemical senses from vision, hearing and the cutaneous senses?
neurogenesis because molecules are exposed to environment
- 5-7 weeks for olfactory receptors
- 1-2 weeks for taste receptors
why are the chemical senses seen as “gatekeepers” of the body
- identify things the body needs for survival (smell/taste good)
- detect things that would be bad for the body (taste/smell unpleasant)
name the 5 basic taste sensation
salty, sour, sweet, bitter, umami
why is sweetness often associated with good components and bitter with bad components
sweet: nutritive + caloric value = automatic acceptance response
bitter: harmful substance = automatic rejection response
what happens when a person is deprived of sodium
seeks out food that taste salty to replenish the salt the body needs
name the four types of papillae that can be found on the tongue
- filiform (cones, entire surface)
- fungiform (mushroom, tip/sides)
- foliate (folds, back)
- circumvallate (flat mounds, back)
which papillae does not contain taste buds
filiform
explain how an electrical signal is generated in the taste cells
stimulus in contact with papillae → taste bud → made of taste cells → tips protrude into taste pore → transduction → electrical signal
name the 4 different types of nerves
- chorda tympani nerve (front and side)
- glossopharyngeal nerve (back)
- vagus nerve (mouth and throat)
- superficial petrosal nerve (top of mouth)
where do the fibers from the tongue, mouth and throat make connections
brain stem in the nucleus of the solitary tract
the primary taste cortex is composed of which part of the brain
insula and frontal operculum
what is another name for population coding
across-fiber patterns
explain the experiment that was done to prove population coding
2 substances with similar pattern should taste the same
- ammonium chloride & potassium chloride similar
- inflicted shock for one of them = avoid the other too
- chooses sodium chloride instead bc different pattern
explain Mueller’s experiment that supports specificity coding
- mice no PTC receptor = don’t avoid (normal)
- mice with PTC receptor = avoid, bitter (cloned)
- mice w Cyx receptor = avoids Cyx (normal)
- mice no Cyx receptor = don’t avoid (cloned)
what is the effect of amiloride
- blocks the flow of sodium into taste receptors
- ↓ neuron response in the brainstem
what mechanisms may be responsible for individual differences in taste
- higher density in taste buds = can taste more
- presence of specialized receptors
differentiate between a microsmatic and macrosmatic person
microsmatic: having poor sense of smell that is not crucial to survival
macrosmatic: having well-developed sense of smell
what method is used to find the detection threshold for odors
forced-choice method
- one trial with weak odorant and other no odorant
- Ps indicate which trial has stronger smell
- threshold = correct response on 75% trials
true or false? difficulty to accurately identify odors results from a deficiency in our olfactory system
false, it results from inability to retrieve the odor’s name from our memory
name some genetically determined individual differences in odor perception
- smell of steroid androsterone different for each person
- sensitive to B-ionone = fragrant, floral
- less sensitivity to B-ionone = sour, pungent, acid
decrease in olfaction is a predictor of which disease
Alzheimer’s
what is one explanation for why COVID causes a decrease in olfaction
COVID molecules attach to ACE2 found in intestines, lungs, arteries, heart and nose
