Gustation

what are the 5 basic tastes

salty

sour

sweet

bitter

umami

what is flavour

variety of sensations aroused by different foods; relies on sense of smell as well as taste

what are papillae

small structures on the tongue that have taste buds

what are the 3 types of papillae that are found on the tongue

circumvallate

foliate

fungiform

what are the major taste function for circumvallate papillae

bitter

what are the major taste function for foliate papillae

sour, salty

what are the major taste function for fungiform papillae

sweet, salty, umami

what do taste cells do

They extend cilia into the taste pore to detect tastants (chemicals responsible for taste).

what is taste pore

It's the opening on the surface of the taste bud where cilia from taste cells are exposed to tastants.

How many basic tastes does each taste cell respond to?

Each taste cell responds to only one of the basic tastes.

Besides taste, what other sensations can taste buds detect?

temperature, pain, and touch via other sensory cells.

what is a common taste myth

people think specific regions of the tongue are each dedicated to a specific taste, but all areas of the tongue can detect all basic tastes

describe how the salt taste is transduced

Na+ ions enter taste cells through sodium channels → causing depolarization, sending information to the brain

describe how the sour taste is transduced

acids in food tastes source

all acid release hydrogen ions H+

sour taste cells have PKD2LI ion channel protein, cell depolarizes → brain get sour signal

describe the sweet, bitter, umami taste is transduced

g-protein-coupled receptors trigger chemical chain reaction inside the cell → releases calcium (depolarization) → sends taste signal to the brain

what receptor detects sweet taste

T1R2 + T1R3

What explains different perceptions of sweet substances?

Different recognition sites within the T1R2+T1R3 receptor complex respond to different sweet tastants.

What receptors detect bitter tastes?

T2R receptors

What paradox exists with bitter taste receptors?

Despite having many T2R receptor types, our ability to discriminate between bitter tastes remains poor.

what are supertasters

individuals with heightened sensitivity to some bitter tastes, suggesting genetic differnces

what indicates a supertaster, compared to to nontasters and medium tasters

supertasters have the most fungiform papillae

medium tasters have an intermediate amount

nontasters have the least

What are 3 ways taste receptor cells can be depolarized?

• Direct ion entry (e.g., Na⁺ for salty)

• Blocking ion channels (e.g., H⁺ blocks K⁺ in sour)

• Activating G-protein-coupled receptors (e.g., sweet, bitter, umami) → leads to intracellular signaling and neurotransmitter release.

What factors may lead to individual differences in tasting ability?

• Genetics (e.g., supertasters have more taste buds)

• Age (taste sensitivity declines)

• Health status (illness or medications can affect taste)

• Cultural experience and exposure

what is umami

meaty, savory flavor

what are the 2 receptors that detects umami flavour

metabotropic glutamate receptor that responds to glutamate (and monosodium glutamate (MSG))

a combination of T1R1 and T1R3 receptors

what is the gustatory system

different tastes are represented in distinct areas in the gustatory cortex (gustatopic map)

activating these areas can influence behaviour

what are the 2 theories of how taste is perceived

pattern coding

labeled lines theory

what is pattern coding in gustation

taste is identified by the combined pattern of activity across many taste receptors

what does it mean that taste is a system of labeled lines

inactivating one taste quality leaves the perception of other taste qualities intact

The labeled line theory says that each basic taste quality (sweet, sour, salty, bitter, umami) is carried by its own dedicated set of neurons

aka: Each taste has its own “labeled wire” to the brain.

what does the current research suggest about taste

taste-like sensors

gut actively samples food composition: cells in stomach and intestine that express sweet receptors

bitter taste receptors in lungs, airways, testes: appear to regulate protective reflexes like sneezing and coughing