Unit 6 Taste And Olfactory Flashcards
Describe the anatomy of our taste receptors
Papilla are the spots on our tongue and they contain taste buds. Each taste bud contains over 50 taste cells. They respond to tastants by releasing neurotransmitters onto sensory fibres
In general how does our sense of taste function
Taste receptor cells connect to nerves that transmit taste signals to your brain. They respond to sweet, salty, bitter, sour, and umami
What are the structures that mediate our sense of taste
Papilla and taste buds
Describe sensory transduction for the salty tastants
Salty foods are high in NaCl. This dissolves in saliva into Na+ and Cl-. The Na+ travels through specialized open Na+channels on salty taste cells which depolarizes the taste cell
Describe the journey of taste information to the brain
Taste information flows from the taste cells to neurons of the facial and glossopharyngeal nerves to targets in the brainstem. From here, info travels to thalamus and anterior insula.
Discuss what we know about supertasters and cilantro
Supertasters are far more sensitive to tastes like the kind in cilantro. Supertaters can taste gross aspects of it because they are more sensitive
Describe the anatomy of the olfactory system
Airborne chemicals travel through the nasal passage until they reach the olfactory epithelium.
The cilia of olfactory receptor neurons (ORNs) contain G-protein coupled olfactory receptor proteins.
Humans possess ~6 million ORNs, each expressing one of the 400 possible olfactory receptor proteins.
The axons of ORNs terminate in the olfactory bulb sorted according to the receptor protein they express.
Describe sensory transduction for olfaction ie how do we smell
An odorant binds to an olfactory receptor protein and this results in depolarization of the olfactory receptor neuron, which can initiate an action potential
Describe the journey of olfactory information to the brain
The olfactory bulb primarily transmits information to the piriform cortex, then to the thalamus or hypothalamus, then to either the lateral posterior obitofrontal cortex or the obitofrontal cortex
Compare orthonasal and retronasal olfaction and their role in the experience of flavor
Orthonasal olfaction involves sniffing volatile chemicals through your nose.
Retronasal olfaction involves the release of volatile molecules from food in the oral cavity, which reaches the olfactory epithelium from the back of the mouth.
Describe sensory transduction for the sweet tastants
Sweet foods contain sucrose. Sucrose binds to and activates a specific G-protein coupled receptor which leads to taste cell depolarization.
Describe sensory transduction for the sour tastants
Sour food are acidic. Acids release H+. Mechanism is not fully understood, but it is thought that an influx of H+ through specialized channels leads to depolarization of the taste cell.
Describe sensory transduction for the bitter tastants
Diverse chemicals evoke a bitter taste sensation. Each bitter tastant activats at least one G-protein coupled receptor of a family of 25 receptors. This leads to depolarization of the taste cell.
Describe sensory transduction for the umami tastants
Foods high in protein evoke a savoury taste sensation. These foods release amino acids when chewed and exposed to salivary enzymes. The amino acids activate a G-protein coupled receptor, depolarizing the taste cell.
