This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Principles of Gastrointestinal Function, Subject name: Physiology
[{'content': 'Last discovered taste sensation - \nSelect and explain. \nA. Sweet, B. Sour, C. Bitter, D. Umami', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Umami o Umami taste sensation is the most recent one, discovered in early 1900s.Taste sensationso There are four basic tastes namely Sweet, bitter, Salty and Sour. There mechanisms of sensory transduction are:o There are different mechanisms of sensory transduction.1) Sweet receptor is a Gprotein coupled receptor and leads to an increase in cAMP concentration in the sensory cells which results in closure of K+ channels and depolarization.2) Bitter receptors are also G protein coupled receptors and causes rise in intracellular Ca+2 by IP3-DAG system. Rise in intracellular Ca+2 triggers neurotransmitter release.3) Salty-tasti ttg substances depolarize taste cells by activating amiloride-sensitive Na+ channels.4) Sour-tasting substances depolarize taste cells by raising the intracellular H+ ion concentration, which causes closure of K+ channels.o The umami taste is the fifth taste which is unique. The proposed mechanism of umami taste is through glutamate taste sensors (glutamate receptors) with release of neuronal glutamic acid.", 'role': 'assistant'}]