Exam 3- Sensation and Perception

Salt

signals ions; ionotropic channel, sodium enters channel

Sweet

signals carbs/energy; metabotropic channel, calcium into cell

Sour

signals bacteria/spoiled food; ionotropic channel, hydrogen enters

Bitter

signals toxins; metabotropic channel, calcium let into cell

Umami

Signals protein; metabotropic, calcium enter cell

4 types of papillae

Taste Function: fungiform, foliate, and circumvallate

No taste function: filiform

Taste buds

Are embedded within papillae

Made of clusters of taste receptor cells

CN on tongue front to back

facial, glossopharyngeal, and vagus

Trigeminal Nerve (5)

Info abut touch, temp, and pain from inside the mouth

Nucleus of Solitary Tract

Brainstem nucleus for taste processing

Ventroposterior thalamus

thalamic nucleus for taste processing

Insula

location of primary taste cortex and has “hot spots” for primary tastes

Orbitofrontal Cortex

processes flavor and important for hedonic value of food

Taste receptor cells

Die and are replaced, synapse with axons of CNs, use serotonin, and have only 1 type of receptor proteins.

Microvillae (part of taste receptor cells)

Location of receptor proteins for taste

Aguesia and Dysguesia

A= complete loss of taste

Dys= altered/decreased perception

Gustotopic map

Clusters of neurons that respond best to each primary taste

Bitter Receptors

Most receptors, lowest threshold, inhibited by compound in breast milk, and sensitivity intensifies with pregnancy and lowers after menopause

25 different receptors on 3 chromosomes

Don’t have their own axons so we don’t differentiate well between them

Salt Receptors

no preference of it until 6 months old, increased preference for it if deficient in infancy, threshold changes depending on exposure, and we develop specific hunger for it (AND SWEET)

Taste vs Supertasters

more fungiform papillae on tongue → more taste buds → more taste receptor cells → more trigeminal innervation

Umami Receptors

binds to glutamate, also called savory/brothy, uses 2 sweet metabotropic receptors

3 metabotropic receptors for sweet

T1R1, T1R2, T1R3

Main sweet receptors: T1R2 + T1R3

Fatty acids and umami receptors

Found in gut relevant to food with high caloric value; signaled via vagus nerve to prefer sensory properties of that food