taste

Meaning: Taste, or gustation, is a chemical sense. Molecules dissolved in saliva bind receptor cells in taste buds, which sit in papillae on the tongue and in parts of the mouth and throat. The five basic tastes are sweet, sour, salty, bitter, and umami (savory). Signals travel through cranial nerves to the brainstem, then the thalamus, then the gustatory cortex. Taste has adaptive value: sweet and umami tend to signal nutrients, while bitter and sour often signal toxins or spoilage.

On the MCAT: Expect questions on sensation and perception. Flavor is taste combined with smell, texture, and temperature, so a blocked nose dulls flavor. Supertasters have more taste buds and respond more strongly to bitter compounds. Constant exposure to one taste leads to sensory adaptation, so its intensity fades. Taste is often compared with olfaction. Both are chemical senses, but olfactory signals reach the olfactory cortex without first passing through a thalamic relay, while taste signals go through the thalamus.

Common confusion: The "tongue map," with sweet at the tip and bitter at the back, is a myth. Taste buds for every basic taste are spread across the tongue, although sensitivity can vary a little by region. Also keep taste (the five qualities) separate from flavor (the whole experience).