How Chemical Sensory Systems Work

For chemical sensory systems (basic tastes, smell, and trigeminal effects) to work, flavor molecules must first reach receptors that detect their presence. Basic taste molecules (sugars, acids, salts, etc.) must dissolve in saliva to reach the taste buds; odor molecules must evaporate to reach the olfactory cells; and trigeminal factors (menthol, capsaicin, ethanol, etc.) must be absorbed through the top layer of skin to reach nerve endings. Once at the site of the receptors, the flavor molecules interact with (stimulate) receptors in some way, for example by bonding to them. Because these receptors are sensitive to different molecules or chemicals and their concentrations, they are called chemoreceptors. Once chemoreceptors are excited, electrical impulses are generated that travel through nerve cells to specific regions in the brain, where the information is processed. The organ that actually perceives is the brain, not the eyes, ears, nose, mouth, or skin.