Lecture_13 - 10/18/05 Chemical Senses Oldest evolved...

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10/18/05 Chemical Senses Oldest evolved senses, tied to emotional areas of the brain Chemosensory systems -3 billion year old chemical senses -Gustatory (taste) -Olfactory (smell) both detect chemicals evolved from origins in water Gustatory Tongue and flavors-taste map (fig 8.2) shows the lowest thresholds for that flavor - Salt - body can be low in salt, it will modify tastes to crave salt - Sweet - high nrg foods are sweet and rare in nature, we like sweet so much because it has an evolutionary reward of being good for us - Bitter - poison related, we don't favor bitter flavors because evolutionary they are dangerous - Sour - acidic (citric acids) - Umami- caused by amino acids (MSG) monosodium glutamate =Savory flavors Flavors vary -Taste is triggered differently depending on what is happening. .. Ketchup turns on all receptors at once -which receptors are turned on -smells add to flavor with odor -texture and temperature vary flavor Receiving flavors (Detecting) Papillae and taste buds (people have average of 2000-5000 taste buds) -fungiform papillae- mushroom shaped -follate papillae- ridge shaped -vallate papillae- pimple shaped ---multiple taste buds on each papillae Taste cells are the actual receptors - Basal cells are stem cells that generate new taste cells (which have a short life span) - Taste pore - flavors enter through here. .. synapse at gustatory afferent axons Tastant- detected by microvilli, synapse at gustatory afferent axons send AP to brain Taste Cell -Receptor potentials in response to tastant -excitatory transmission -can register multiple flavors -Transduction- taking environmental stimulus and converting to nerve impulse
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Tastant Transduction -directly pass through ion channels (salt and sour)
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Lecture_13 - 10/18/05 Chemical Senses Oldest evolved...

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