click below
click below
Normal Size Small Size show me how
S & P
Gustation: the sense of taste
Question | Answer |
---|---|
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). |