Chapter 16 Flashcards
gustation
taste
olfaction
smell
how are taste and smell “gatekeepers” of the body
identify things to survive or reject
create good and bad emotional responses
how long do taste and olfactory receptors live and die
taste: 1-2 weeks
smell: 5-7 weeks
5 basic taste sensations
salty (sodium chloride)
sour (hydrochloric acid)
sweet (sucrose)
bitter (quinine)
umami (meaty, brothy, savory, MSG)
function of taste
determine which substances to consume and avoid
sweetness (often offers nutritive value)
bitter (potentially harmful)
salty (crave salty foods if body is depleted from sweating)
papillae
ridges and valleys in the tongue
filiform (shaped like cones; entire tongue)
fungiform (mushrooms; tip and sides)
foliate (folds; back of sides of tongue)
circumvilliate (flat mounds; back of tongue)
taste buds
located in all papillae except for filiform
whole tongue has 10,000
each taste buds has 50-100 taste cells (identify different types of chemicals for taste)
transduction of tase
chemicals from receptor sites in tip of the taste cells turn into electrical signals for the brain to interpret taste
electrical signals sent to different nerves:
chorda tympani (from front and sides of tongue)
glossopharyngeal (from back of tongue)
vagus (from mouth and throat)
superficial petronasal (from soft palette located in top of mouth in the back)
where do electrical signals from the tongue, mouth, and throat travel through to the brain
nucleus of solitary tract (brain stem) and onto thalamus
then signals travel to primary taste cortex in frontal lobe (insula and frontal operculum cortex)
population coding
neurons that detect a combination of taste (generalized)
aka across fiber patterns
rats cannot distinguish certain taste over others (neurons fire for similar chemicals)
specificity coding
neurons detect a specific type of taste
PTC and PROP (chemical found in humans for detecting bitterness)
experiments on PTC and PROP
tasters (have more taste buds)
nontasters (lack of taste buds for bitterness)
super tasters (more sensitive than tasters for bitterness)
function of olfaction
important for survival
helps us to be aware of dangerous smells
macrosmatic smell
heavily reliant on smell
for animals, keen sense of smell is necessary for survival
provides cues for location and food
microsmatic smell
for humans, less keen sense of smell
not crucial to survive
pheromones
odor molecules emitted by member of species, causing a specific reaction to another individual of the same species
research on pheromones
men rate women’s shirts more pleasant when they are on their menstrual cycle
men had higher testosterone levels when smelling shirts of woman who were ovulating
isolated congenital anosmia (ICA)
people who were born without sense of smell
report feeling more socially insecure
anosmia
inability to smell due to injury or infection
problematic for detecting taste because smell and taste are well connected
how many different odors can humans discriminate
a trillion
difference between identifying and naming odors
identifying (knowing that odor has certain smell but cannot label exact smell)
naming (being able to label the smell can transform our perception into identifying that odor)
two stages of perceiving odor
first stage (analyzing odor, transduction of odor)
second stage (synthesizing odor; putting together and organizing odor info to perceive smell)
olfactory mucosa
dime sized region at top of inside of nasal opening but below olfactory bulb
contains olfactory receptor neurons (ORN), important for odor chemicals to be carried as electrical signals to brain
ORN have olfactory receptors (area of neuron that receives odor molecules)
10,000 ORNs for each one of the 400 types of olfactory receptors
ORN carries odor chemicals, received by olfactory receptors in olfactory mucosa
glomeruli
responsible for collecting info about ORN’s electrical signals that would then be processed in the brain
in olfactory bulb
each type of olfactory receptors sent to one or two of these glomeruli
olfactory process
olfactory mucosa (ORN and olfactory receptors) -> olfactory bulb (glomeruli) -> piriform cortex, orbitofrontal cortex, amygdala
where do neurons fire from olfactory bulb
piriform cortex (primary olfactory area; perceived odors; located in temporal lobe area)
orbitofrontal cortex (secondary olfactory area; perceives odors; in frontal lobe)
amygdala (involved with emotion associated to smell and other senses)
odor objects
where smell is coming from
forming representations involves learning and memory (repeated exposure creates link)
flavor
ability to experience and identify foods and drinks consumed comes from both mouth and nose
flavor involved in retronasal route (from mouth to nasal pharynx – passage to nose)
chemical molecules still reaching olfactory mucosa as foods and drinks consumed in mouth to help identify flavors
in orbitofrontal cortex (from primary gustatory cortex)
oral capture
sensations we experience from both olfactory and taste receptors are seen as only coming from mouth
two influences of flavor
expectation
sensory specific satiety
Proust effect
ability to remember events based on taste and smell senses because of amygdala and hippocampus
