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S & P

Gustation: the sense of taste

QuestionAnswer
Describe the sense of taste Evolved to signal info about chemical & nutritive content of potential foods. We discriminate between appetitive and aversive stimuli, seek/avoid as needed.
What are the stimuli for gustation? Soluble chemicals
What are the 5 taste qualities recognized in mammalian taste? ~Sweet ~Salty ~Umami (Appetitive) & ~Sour ~Bitter (Aversive)
How do taste receptor cells behave like neurons? Sensory stimulation (binding of a tastant molecule) produces a change in the membrane potential that leads to neurotransmitter release.
Where are the taste receptor cells located? There are about 100-150 receptor cells located in the taste buds. The TRCs are housed in papillae and microvilli protrude into oral cavity to contact tastant molecules.
Where are mammalian taste buds in the mouth? Primarily present in papillae on the tongue, but they are also present on the soft palate, pharynx, esophagus and epiglottis
Name the three major nerve fibers involved with gustation. !. Facial Nerve (CN VII). 2. Vagus Nerve (CN X). 3. Glossopharyngeal Nerve (CN IX).
What is Aguesia? Rare condition where all three nerve fibers are damaged/destroyed causing a person to lose their sense of taste.
Explain how taste transduction works for salts and acids. Stimulus/ion channel interaction -> membrane depolarization -> AP initiation -> Ca influx (increase in intracellular Ca) -> release of transmitter -> activation of gustatory afferent neurons
Explain how taste transduction works for complex stimuli Stimulus binds to g-protein coupled receptors -> activation of complex g-proteins -> release of Ca from intracellular stores -> cation influx? Then we don't really know what happens next.
Describe the taste information projection thru the brain. Looks ipsilateral. Axons from nucleus of the tract -> Thalamus -> Gustatory cortex -> Orbito-frontal cortex
What is the insular cortex? The lobe which the gustatory cortex is located on. It is also involved in pain perception - localizing pain sources.
What is flavor and where is it processed? Flavor is produced by the combination of taste and smell, and is affected by chemisthesis, texture, temperature, and motivational state. Flavor is processed in the Orbito-Frontal Cortex. (OFC=Flavor Cortex)
What is the Common Chemical Sense and what is its function? Feeling that accompanies smell & tastes. Functions as a protective mechanism to warn of potentially irritating substances. Stimuli are volatile & soluble chemicals which typically sting or burn (CO2 in soda, menthol, chilies, cinnamon).
Explain how the somatosensory system is involved with gustation. There are free-nerve ending receptors in nose and mouth and polymodal nocioceptors. Cranial n. V & trigeminal n. carry info to the SSC where there is precise mapping of sensory info including CCS and Pain.
What is the test used to detect supertasters vs. non tasters? Originally PTC test accidentally developed by careless chemist in 1930s. Later changed to PROP test. Familial trait to taste or not.
Who is Linda Bartoshuk? First to coin the concept "supertasters" Determined that the average genetic variation in taste for humans is 25% non-tasters, 50% medium tasters, & 25% supertasters
Describe some of the demographics of supertasters. ~Women > men. ~Asians, Africans, S. Americans > others. ~Typically, supertasters are thinner bc they avoid very salty, fatty, sugary foods. ~May lead to being a picky eater, but not all picky eaters are supertasters.
What is the fundamental difference between supertasters and non-tasters? On the tip of the tongue, supertasters have many more fungiform papillae than non-tasters, and around each papillae you will find nocioceptors. More pain receptors means greater sensitivity to spicy, bitter, minty, alcohol, etc.
Evolutionary advantage to being a supertaster? Avoidance of potentially toxic plant alkaloids, limit of range of palatable foods, health consequences - decreased likelihood of tobacco/alcohol addiction.
Consequences of being a supertaster Decreased intake of fatty foods and decreased intake of fruits & veggies
We don't all live in the same taste world. What can influence these individual differences? Differences in taste preferences can be influenced by learning & cultural factors. Individual differences in taste experience can be due to taste receptor expression (may explain bitter aversion in children which is overcome by many as they get older).
Created by: cassidylm34