Molecules from food and other substances enter the nasal passages and mouth where are dissolved in watery mucus and fit into molecular slots, or pockets, in special receptor cells. The binding together of the molecule and receptor stimulates the cell to send electric signals along a pathway of nerve cells to the brain.
Taste (gustation) and smell (olfaction) are called chemical senses because both have sensory receptors that respond to molecules in the food we eat or in the air we breathe.
