Various degrees of colorblindedness occur if one or more of the pigments is missing. Colorblindness is inherited as a sex-linked trait. Colorblind individuals usually cannot distinguish between red and green. The sense of taste results from chemical reactions occurring in the 10 thousand or more chemoreceptors in taste buds scattered on the surface of the tongue. Most taste buds are found between projections called papillae on the surface of the tongue, but others occur on the roof of the mouth and in the throat.
Humans can taste only sweet, sour, bitter, and salt.
Complex flavors are actually distinguished by our sense of smell. Stimulation of nerve endings in the taste buds result in messages carried by nerves to the cerebrum, where the sensation is interpreted. Smell Chemoreceptors responsible for smell are located in the mucus-covered lining of the upper nasal cavity. The sense of smell in humans is surprisingly sensitive. Before the dendrites of specialized sensory neurons, or olfactory receptors , in the nasal epithelium are activated, substances must be dissolved in the watery mucus secreted by the mucus membrane.