Smell and taste are chemical senses: they detect chemicals rather than light or sound waves.
Olfactory receptor cells in the nose detect airborne molecules and transduce them into neural signals sent to the brain.
Smell is the exception that bypasses the thalamus, going directly to limbic areas for emotion and memory, which is why smells can trigger vivid memories.
Taste receptor cells inside taste buds detect food chemicals, and there are six basic tastes: sweet, sour, salty, bitter, umami, and oleogustus.
People differ in taste sensitivity: supertasters have more taste buds and taste more intensely than medium tasters and non-tasters.
Smell contributes greatly to flavor, so food tastes bland with a stuffy nose even though the taste buds still work.
Key terms
chemical senses
Senses that detect chemicals rather than waves: smell and taste.
olfaction
The sense of smell.
olfactory receptor cells
Cells in the nose that detect airborne molecules and transduce them into neural signals.
pheromones
Chemical messages released by members of the same species, some acting as sexual attractants.
gustation
The sense of taste.
taste buds
Structures in the bumps on the tongue that contain taste receptor cells.
umami
A savory taste, such as the taste associated with meat.
oleogustus
The taste of fat.
supertasters
People with more taste buds who experience tastes more intensely, often finding bitter foods unpleasantly strong.
medium tasters
People with average taste sensitivity.
non-tasters
People with lower-than-average taste sensitivity.
Watch out
Smell is the sense that skips the thalamus; other senses route through it.