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Gustation

Gustation. Taste Receptor Cells. Taste cells are transformed epithelial cells that reside in taste buds in the papillae of the tongue, palate, pharynx, epiglottis, and esophagus Circumvallate Papillae Fungiform papillae Filliform papillae

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Gustation

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  1. Gustation

  2. Taste Receptor Cells Taste cells are transformed epithelial cells that reside in taste buds in the papillae of the tongue, palate, pharynx, epiglottis, and esophagus Circumvallate Papillae Fungiform papillae Filliform papillae Saliva contacts the microvilli through the taste pore The solubility of a substance affects the response time

  3. Salty EnAC Sodium Channel NaCl – Ion channel allows Na⁺ to enter the cell Depolarization occurs and voltage-gated Ca²⁺ channels open Ultimately leads to neurotransmitter release

  4. Sour • EnAC protein • H⁺ blocks K⁺ channels increasing intracellular [K⁺] via the MDEG1 receptor • H⁺ also binds to yet another protein which allows Na⁺ ions to flow down the concentration gradient into the cell • Bitter • G protein coupled receptor (GCPR) - gustducin • Activated phosphodiesterase leads to conversion of cAMP to AMP • cAMP holds K⁺ ions open – so intracellular K⁺ concentration ↑

  5. Sweet • GPCRs coupled with gustducin • Adenylate cyclase becomes active increasing [cAMP] • Ca²⁺ channels open inreasing intracellular [Ca²⁺] • K⁺ channels close • Umami (Savory) • Similar to the bitter and sweet pathways • L-glutamate binds to mGluR4 (a GPCR) • mGluR4 is thought to close a cation channel which causes depolarization • Fats? • Spicy … ??? • Spicy is not a taste receptor cell • Temperature sensitive receptors respond to spicy foods • Tactile receptors also present information about a substance’s texture

  6. Comparative Taste Cells • Drosophila melanogaster has taste bristles containing gustatory receptor neurons at the end of the proboscis as well as on the legs and anterior wing margins • Internal taste organs line the walls of the pharynx • Sensation of harmful substances regurgitate response • Sensation of pleasurable substances sucking reflexes

  7. So why do different people have different food preferences?

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