Taste
From Wikipedia, the free encyclopedia
Taste is one of the traditional five senses and refers to the ability to detect the flavor of foodstuffs and other substances (e.g. poisons). In humans and many other vertebrate animals the sense of taste partners with the sense of smell (also called olfaction), in the brain's perception of flavor. Classical taste sensations include sweet, salty, sour, and bitter. More recently, psychophysicists and neuroscientists have suggested other taste categories (umami and fatty acid taste most prominently.)
Taste is a sensory function of the central nervous system. The receptor cells for taste in humans are found on the surface of the tongue, along the soft palate, and in the epithelium of the pharynx and epiglottis.
Contents |
[edit] Role of the nervous system
In humans, taste stimuli are transduced by taste receptor cells which are most commonly found in clusters called taste buds. Taste cells excite sensory afferents found in three of the twelve cranial nerves. The facial nerve relays information from the anterior two thirds of the tongue and soft palate, the glossopharyngeal nerve from the posterior one third of the tongue, and the vagus nerve from the pharynx and epiglottis. Information from these cranial nerves is processed centrally first in the nucleus of the solitary tract of the medulla oblongata and then by a variety of forebrain and cortical structures.
[edit] Basic classification of tastes
Psychophysicists have long suggested the existence of four taste 'primaries', referred to as the basic tastes: sweetness, sourness, bitterness, and saltiness. Umami, or savoriness, has been suggested as a fifth basic taste, exemplified by the non-salty sensations evoked by MSG (monosodium glutamate). Other possible categories have been suggested, such as a taste exemplified by certain fatty acids such as linoleic acid (see [1], [2], [3]). Some researchers still argue against the notion of primaries at all and instead favor a continuum of percepts similar to color vision.
All of these taste sensations arise from all regions of the oral cavity, despite the common misperception of a "taste map" of sensitivity to different tastes thought to correspond to specific areas of the tongue [4]. The "mouth map" is a myth, generally attributed to the mis-translation of a German text, and perpetuated in North American schools since the early twentieth century [1]. Very slight regional differences in sensitivity to compounds exist, though these regional differences are subtle and do not conform exactly to the mythical tongue map. Individual taste buds (which contain approximately 100 taste receptor cells), in fact, typically respond to compounds evoking each of the four basic tastes.
[edit] Factors affecting taste perception
Many factors affect taste perception, including:
- Aging
- Color/vision impairments
- Hormonal influences
- Genetic variations - See Phenylthiocarbamide
- Oral temperature
- Drugs and chemicals
- CNS Tumors (esp. Temporal lobe lesions)
- Plugged noses
It is also important to consider that flavor is the overall, total sensation induced during mastication (e.g. taste, touch, pain and smell). Smell (olfactory stimulation) plays a major role in flavor perception.
[edit] Disorders of taste
- ageusia (complete loss)
- hypogeusia (partial loss)
- parageusia (unpleasant taste)
- dysgeusia (inaccurate taste)
[edit] See also
- Connoisseur
- Supertaster
- Electronic Tongue
[edit] References
- ^ Lindemann, Bernd (1999). "Receptor seeks ligand: On the way to cloning the molecular receptors for sweet and bitter taste". Nature Medicine 5 (4): 381.
