Our mouths contain over 100,000 taste buds, which are comprised of groups of taste cells, which recognize different types of tastes or "flavors". Taste cells have different taste receptors, which are typically G-protein coupled receptors embedded in the membranes of the cells. When a G-protein coupled receptor is activated by binding of a particular ligand that corresponds to a particular taste type, it sets off a second messenger cascade and depolarizes the cell. Each taste type has a different corresponding second messenger cascade, but in all cases the result is the transduction of a signal to the nerve endings at the base of the taste buds. There are three types of nerves that are involved in this relaying information to the brain: the hypoglossal nerve, the facial nerve, and the glossopharyngeal nerve.