Basic Tastes


Chemical senses

Far sense





Near sense


Odor compounds






Olfactory bulb

Olfactory neuron







Sensory receptor cell




Taste buds

Taste compounds

Taste receptor cell









Definition of Terms

. Basic Tastes - there is a widely held (although not universally accepted) belief that all taste sensations arise from a combination of a limited set of 4 (or 5) basic tastes. There is no precise definition of "basic tastes" - they are defined by prototypical stimuli. The four traditional basic tastes (and their prototypical stimuli) are sweet (sugars, especially sucrose), sour (acids, especially citric acid), salty (sodium chloride, or table salt), and bitter (alkaloids, like caffeine and quinine). The fifth widely accepted basic taste is umami (monosodium glutamate, the primary compound in AccentTM, and 5' nucleotides, such as IMP and GMP).

Chemesthesis - sensations that arise when chemical compounds activate receptor mechanisms for other senses, usually those involved in pain, touch, and thermal perception in the eye, nose, mouth and throat. The burn from chili pepper, the cooling from the menthol in mouthwash, and the stinging of carbonation in the nose are all examples of chemesthesis.

Chemical senses - Senses that detect chemicals in the environment (e.g., air, water, food, and drinks). In humans, they are located in the nose (olfaction) and mouth (gustation).

Far sense - A sense that can detect items in the environment at a distance (e.g., vision and hearing)

Flavor - the combination of taste and smell, and some experts like to define flavor as the combination of taste, smell, and chemical irritation

Gustation - sensations that arise from the stimulation of taste receptor cells found throughout the mouth

Gustatory - of or relating to gustation or the sense of taste

Kinaesthetic  - of or relating to the ability to feel movements of the limbs and body due to muscle-feedback

Near sense - A sense that can only detect items in the environment when they come in contact with the organism (e.g., taste, smell, chemesthesis, and touch).

Neuron - also called nerve cell, it is a specialized cell of the nervous system that conducts messages from one part of the body or brain to another part.

Odor compounds - hydrophobic, volatile compounds that are typically larger than taste compounds. Such compounds must be volatile (readily evaporating) and hydrophobic (tending to dissolve in oil and not in water) so they can evaporate in the air, penetrate surrounding layers, and interact with olfactory neurons.

Odorant - an odor compound

Olfaction - sensation that arises from the stimulation of olfactory neurons  located in the nose, specifically the olfactory bulb. Odor compounds can reach the olfactory neurons through two different pathways.

Orthonasal stimulation - Olfaction arising from odor compounds traveling through the “external nares,” or nostrils, to the olfactory bulb.

Retronasal stimulation - Olfaction arising from odor compounds traveling through the “internal nares,” located inside the mouth. This is why if you pinch shut your nose, take your medicine, and swallow, you can STILL smell the cough syrup once you let go of your nose. Molecules that stimulate olfactory receptors are still floating around in your mouth, up through your internal nares, and can stimulate the olfactory neurons located in the olfactory bulb.

Olfactory -  of or relating to olfaction or the sense of smell

Olfactory bulb - one of two clusters of olfactory neurons at the base of the brain (one on the left and one on the right). From either structure, the olfactory neurons extend through a porous bone and interact with the environment inside the nose.

Olfactory neuron - a neuron that transduces an odorant into a neural signal and transmits olfactory information to the brain.

Papilla - A small, round or cone-shaped bump on the surface of the tongue. There are several types of papillae in the mouth, and all but one type contain taste buds.

Fungiform - taste bud-containing papillae located on the front two-thirds of the tongue. They can be seen as red bumps (the bumps that stand out in contrast to the pinkness of the rest of your tongue); under magnification, they look a bit like mushrooms (fungi).

Circumvallate - taste bud-containing papillae toward the very back of the tongue; they are placed in an inverted “V.” It can be very hard to see your own, but it is fairly easy to see these in another person, especially if you use a flashlight.

Foliate - taste bud-containing papillae located very far back on the sides of the tongue; they look like a series of folds or lines and can be very difficult to see.

Filiform - papillae that do not contain taste buds. They cover the surface of the tongue in great abundance and are largely responsible for the texture of the tongue. The only purpose it serves in tasting is that it can help to hold taste compounds on the tongue, increasing the chance that the taste compound will interact with a taste receptor cell.

Psychophysics - a branch of psychology that quantitatively examines the relationships between physical stimuli and their perceptual effects

Sensory receptor cell - an organ having nerve endings (in the nose or mouth or eye, etc.) that respond to stimulation and transmits a neural signal to the brain.

Smell - see Olfaction

Tastant - a taste compound

Taste - see Gustation

Taste buds - a specialized structure made up of taste receptor cells and supporting cells; the smallest functional unit of the sensing portion of the gustatory system

Taste compounds - hydrophilic, water-soluble compounds that are typically smaller than odor compounds

Taste receptor cell -  a sensory receptor cell that transduces a tastant into a neural signal and transmits gustatory information to the brain

Transduction - a process found in all sensory systems whereby one form of energy is converted into another, i.e., sound waves are converted into an electrochemical signal, or contact with an odor compound is converted into an electrochemical signal

Umami - There are many prominent researchers who believe in the existence of a fifth “basic taste,” called “umami.” This taste is associated with the taste of MSG (monosodium glutamate, the primary compound in AccentTM) and is described as a “brothy” or “savory” taste.


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