S&P chapter 16

3 components of chemical senses

taste - food enters the mouth which stimulates receptors on the tongue

olfaction - molecules enter the nose which stimulate receptor neurons in the olfactory mucosa

flavor - combo of taste and olfaction

length of time for receptors to undergo a cycle of birth, development, and death for olfactory receptors

5-7 weeks

length of time for receptors to undergo a cycle of birth, development, and death for taste receptors

1-2 weeks

neurogenesis

constant renewal of receptors

5 basic taste qualities

salty, sour, sweet, bitter, Umami (meaty, brothy, savory, associated with monosodium glutamate). spicy isn’t on this list because its somatosensory

papillae

ridges and valleys on the tongue, some of which contain taste buds

filiform

Shaped like cones and are found over the entire surface of the tongue, giving it its rough appearance

fungiform

Shaped like mushrooms and are found at the tip and sides of the tongue

foliate

Series of folds along the back of the tongue on the sides

circumvallate

Shaped like flat mounds surrounded by a trench and are found at the back of the tongue

amount of taste cells in each taste bud

50 to 100

taste pore

tips of taste cells that protrude into the taste pore

signals from taste cells travel along a set of pathways:

•Chorda tympani nerve from front and
sides of tongue

•Glossopharyngeal nerve from back
of tongue

•Vagus nerve from mouth and throat

•Superficial petronasal nerve from soft palate

these pathways make connections in

nucleus of the solitary tract in medulla

then, they travel to the… Followed by areas in the frontal lobe…

thalamus. insula, frontal opervulum cortex, orbital frontal cortex.

population coding for taste experiment

-different taste stimuli presented to rats, recordings were made from the chorda tympani

-showed that 2 substances (ammonium chloride and potassium chloride) are similar to each other but different from sodium chloride.

specificity coding for taste

-mouse: PTC + Cyx chemicals

tasters

people who can taste PTC. 2//3 can taste PROP

nontasters

those who can’t taste PTC. 1/3 can’t taste PROP

people who can taste PROP have ____

higher densities of taste buds than those who can’t taste it

supertasters are more

sensitive to bitter substances than tasters.

microsomatic

having a poor sense of smell that is not crucial for survival

macrosomatic

having a well-developed sense of smell

detection thresold

the lowest concentration at which an odorant can be detected

forced-choice method

-participants presented with blocks of two trials– one trial contains a weak odorant, the other, no odorant

-Task = indicate which trial has a stronger smell

-threshold determined by measuring the concentration that results in a correct response on 75% of the trials

rats are ___ more senstivive to odors than humans

8 to 50 times

dogs are ___ more sensitive to odors than humans

300 to 10,000 times more sensitive

humans have ___ olfactory receptors and dogs have ____ olfactory receptors

10 million, 1 billion

humans can discriminate more than ____ different odors

1 trillion

COVID molecules attach to

any enzyme

ACE2 is found in

intestines, lungs, arteries, heart, nose. also found on surface of sustentacular cells

sustentacular cells can provide

metabolic and structural support to the olfactory sensory neurons

COVID causes loss of smell by

affecting their supporting cells

alzheimers disease

serious loss of memory and cognitive functions that come before mild cognitive impairment. loss of smell comes decades before other symptoms

olfactory mucosa

Dime-sized region located on the roof of the nasal cavity below the olfactory bulb

olfactory receptor neurons

Receptors in the olfactory mucosa (colored circles, tan part = supporting cells)

glomeruli

where olfactory neurons synapse onto the olfactory bulb

2 main olfactory areas

piriform cortex, orbitofrontal cortex

piriform cortex

primary olfactory area

orbitofrontal cortex

second olfactory area

amygdala is involved in

determining emotional reactions to smell

odor stimuli from food in the mouth reaches the olfactory mucosa through the ___

retronasal route

____is not influenced by olfaction

monosodium glutamate (savory taste)

responses from taste and smell are first combined in the

orbital frontal cortex

bimodalneurons

neurons that respond to 2 types of information (taste and smell, taste and vision)

____ is impacted by how hungry we are

firing rate

flavor being influenced by a persons expectations

participants couldn’t tell the difference in wine when the price was hidden. when the price was revealed, the participants said they were more satisfied with the expense wine.

flavor being influenced by hunger

when hungry and before consuming food, the pleasantness for both banana and vanilla were high. after consuming food, both pleasantness ratings decreased