Binding of a sugar molecule to a receptor cell initiates a signal transduction pathway involving cyclic AMP and protein kinase A.

K⁺ channels in the membrane close, and the membrane depolarizes.

Voltage-gated calcium Ca²⁺ channels open, and Ca²⁺ diffuses into the receptor cell.

Synaptic vesicles release neurotransmitters, sending signals to the sensory neuron.