Taste is the ability to respond to dissolved molecules and ions called Testants. Humans detect taste with taste receptor cells. These are clustered in taste buds. Each taste bud has a pore that opens out to the surface of the tongue enabling molecules and ions taken into mouth to reach the receptor cells inside. A single taste bud contains 50-100 taste cells representing all 5 taste sensations. Each taste receptor cell is connected, through an ATP releasing synapse, to a sensory neuron leading back to the brain. There are five primary taste sensations (1) salty (2) sour, (3) sweet (4) bitter and (5) umani.