Question: what are taste buds sensitive to?
Answer: See all those bumps? Those are called papillae (say: puh-PILL-ee), and most of them contain taste buds. Taste buds have very sensitive microscopic hairs called microvilli (say: mye-kro-VILL-eye). Those tiny hairs send messages to the brain about how something tastes, so you know if it's sweet, sour, bitter, or salty.