PHED-2506EL Lecture Notes - Lecture 17: Solitary Nucleus, Mechanoreceptor, Limbic System
25 Jun 2018
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Lecture objectives: Taste
** There are no objectives for taste, so I have summarized the key points in the lecture**
-Taste is a chemical sense (gustation)
-Chemoreceptors respond to chemicals in aqueous solution (respond to substances dissolved in
saliva)
-10,000 taste buds are found on the tongue
-Taste buds are found in papillae of the tongue mucosa
-Papillae come in three types: filiform, fungiform, and circumvallate
Anatomy of the taste bud
Contain three major cell types:
Supporting cells- insulate the receptor
Basal cells- dynamic stem cells
Gustatory cells- taste cells
Taste Sensations
Sweet (sugars and some amino acids)
Salt (metal ions)
Sour (hydrogen ions, their pH levels display acidity)
Bitter (alkaloids)
Umami (elicited by amino acid glutamate, meaty taste)
Physiology of taste
For a chemical to be registered as a taste, it must be dissolved in saliva, diffuse into the taste
pore, and contact a gustatory hair. The binding of a food chemical or tastant to the receptors
on the taste cell membrane induces a graded depolarization that causes a neurotransmitter to
be released. With salty tastes, a Na+ influx through Na+ channels directly depolarizing the taste
cells. Sour tastes are mediated by H+, which act intracellularly to open ion channels, leading to
cell depolarization. Bitter, sweet, and umami responses stem from a mechanism similar to that
of the sour tastes, but the depolarizations occur in different cells. The bitter, sweet, and umami
taste receptors are coupled to a common G protein called gustducin. Activation of gustducin
leads to Ca+ release. This Ca+ release causes the opening of ion channels in the plasma
membrane, depolarizing the cell. The binding of a neurotransmitter released after the
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Document Summary
** there are no objectives for taste, so i have summarized the key points in the lecture** Chemoreceptors respond to chemicals in aqueous solution (respond to substances dissolved in saliva) 10,000 taste buds are found on the tongue. Taste buds are found in papillae of the tongue mucosa. Papillae come in three types: filiform, fungiform, and circumvallate. Sour (hydrogen ions, their ph levels display acidity) Umami (elicited by amino acid glutamate, meaty taste) For a chemical to be registered as a taste, it must be dissolved in saliva, diffuse into the taste pore, and contact a gustatory hair. The binding of a food chemical or tastant to the receptors on the taste cell membrane induces a graded depolarization that causes a neurotransmitter to be released. With salty tastes, a na+ influx through na+ channels directly depolarizing the taste cells. Sour tastes are mediated by h+, which act intracellularly to open ion channels, leading to cell depolarization.
