olfactory system - university of south dakotaapps.usd.edu/coglab/schieber/pdf/chemicalsenses.pdf ·...
TRANSCRIPT
Olfactory System
Gross Anatomy
Olfactory Epithelium
Olfactory Bulb
Olfactory Transduction
Ascending Pathways
Henning’s Smell Prism
One Face of the Henning Smell Prism
MultiDimensional Scaling
Highly Diverse Smell Thresholds
Odor Identification
Flavor without Smell
Taste
Question: How do we taste? Answer: Like pork. (Anonymous cannibal)
4+1 Taste Primaries
Salty Sour Sweet Bitter Umami
Safe (approach) Acidic; poor nutritional value (avoid) Nutritious (approach) Poisonous (avoid) Amino acids; rich protein source (hearty; savory)
Flavor Perception
Olfaction Taste Texture Temperature Consistency Common chemical sense “heat” of red pepper “coolness” of menthol
Anatomy of the Tongue Papillae; Taste buds; Taste receptor cells; Microvilli
Types of Papillae
Taste “Map” Myth Exposed
Transduction
Sweet; Bitter; Umami G-protein receptor site woven through microvillus wall Taste molecule interacts with G-protein: inhibits ionic flow across membrane; cell depolarizes and starts firing (action potential)
Transduction
Salty Na+ ions diffuse across microvillus wall; depolarizing cell; action potentials generated
Sour H+ ions bind to receptor sites; inhibit K+ pumps; cell depolarizes and generates neural “spikes” [H+] corresponds to acidic strength (i.e., pH)
Receptor / “Labelled Lines” Theory
Taste Pathways
Absolute Threshold
Bitter Quinine 0.000008 M Sour HCl 0.0009 M Salty NaCl 0.01 Molar Sweet Sucrose 0.01 M --------------------------------------------------- Umami Glutamate 0.0007 M
Individual Differences in TB Count [Taste Lab]
Super-Taster Normal Taster
Temperature vs. Sensitivity