NROC64H3 Lecture : CHAPTER 8.docx
Document Summary
Chemical sensation is the oldest and most common of the sensory systems. Gestation and olfaction both detect environmental chemicals; must use both to perceive flavor. Saltiness, sourness, sweetness, bitterness, and umami (delicious; defined by savory taste of the amino acid glutamate; monosodium glutamate, msg) Artificial sweeteners are 10,000-100,000 times sweeter than sucrose. Bitter substances range from simple ions like k+ (kcl evokes bother bitter and salty tastes) and mg2+ to complex organic molecules such as quinine and caffeine. Each food activates a different combination of the basic tastes. Distinctive flavor as a result of their taste and smell occurring simultaneously. Other sensory modalities such as texture and temperature and pain sensations (spicy foods) Taste is primarily a function of tongue, but regions of pharynx, palate, and epiglottis have some sensitivity. Odors can also pass via pharynx into nasal cavity where detected by olfactory receptors. Tip of tongue most sensitive to sweetness, back to bitterness, and sides to saltiness and sourness.