chemical senses

foods taste sour because of

high acidity

sour taste mechanism: H+ released by

acids uses Na+ channels to enter & depolarizes cells; simultaneously, H+ blocks K+ channels

sweetness:

some molecules bind specific receptors, activating second messengers to initiate a cascade of reactions within taste cells; such as cAMP, IP3 (most common)

bitter taste receptors are poison detectors

some bitter compounds block K+ channels; most bitter compounds use the second messenger IP3 to transduce signals

unami refers to the taste of proteins (or amino acids)

the transduction process involves the second messenger IP3

to tell sweetness, bitterness, & unami apart

taste cells selectively express only one type of taste receptor