According to KidsHealth, the average human tongue has about 10,000 taste buds. In many people, there is a regular turnover every two weeks and all the taste buds are replaced.
This substitution process is less efficient over time, and some buds are not restored, KidsHealth notes. Older adults have about 5,000 functioning taste buds.
KidsHealth explains that taste buds work through their tiny hairs, or "microvilli," which transmit messages to the brain. The brain then lets the person know what taste has been detected: sweet, sour, bitter or salty. Taste is also affected by "olfactory receptors" in the nose, which also contact the brain. The combination of taste buds and these receptors is responsible for determining full flavors of foods.