Psych 454 1st Edition Exam 2 Study Guide Lec 14 I II III IV V Intro A Anosmia loss of smell 1 5 of general population B Olfactory organ 1 Olfactory epithelium olfactory receptor cells ORCs supporting cells basal cells 2 Cribriform plate a thin sheet of bone through which small clusters of axons penetrate coursing to the olfactory bulb Signal transduction A Odorants bind to specific receptors cAMP binds to cation channels influx of Na and Ca2 Ca2 activated Cl channel Olfactory bolb OB A Receives input from the olfactory nerve B The first relay station in the olfactory pathway C Odorant concentration coding in ORCs and OB D 1st relay station 1 each odor is represented by the activity of a large population of neurons 2 neurons responsive to particular odors may be organized into spatial maps 3 the timing of action potentials may be an essential code for particular odors E summary of olfactory pathways 1 frontal cortex conscious perception of smell 2 hypothalamus amygdala motivational and emotional aspects of smell 3 hippocampus odor memory Characteristics of olfaction A Most primitive sensory system B Olfactory sensory cells are true neurons C Only one relay station from the outside world to cortical tissue D Olfactory fatigue adaptation the temporary normal inability to distinguish a particular odor after a prolonged exposure to that airborne compound Main and accessory olfactory system MOS and AOS A Found in addition to the MOS in terrestrial vertebrates B Initiated in vomeronasal organ VNO and is mainly used in the detection of pheromones VI VII C Does AOS exist in humans 1 Vistible vestigial human VNO 2 Trpc2 is a pseudo gene in human 3 Absence of the VNA did not affect the detection of the putative human pheromone Pheromone A Chemical molecules released to elicit specific behavioral expressions or hormonal changes from other individuals of the same species B Important signals 1 Reproductive behavior 2 Territorial boundaries 3 Identification 4 Aggression C Role in humans 1 Pheromone communication in humans may be conveyed via the main olfactory system Summary A Intro 1 The role that olfaction played in everyday life anosmia B Olfactory pathway 1 Signal transduction 2 Olfactory bulb 3 Summary of olfactory pathway C Characteristics of olfactory system D Main and accessory olfactory pathway 1 Accessory olfactory pathway 2 Pheromone detection in human Lec 15 I II 5 basic tastes A salty tastes like salt NaCl B sour acids HCL C sweet sugars and sucrose some proteins artificial sweeteners D bitter range of different substances simple ions and complex organic molecules 1 poisonous substances are often bitter 2 we can detect very low concentrations of bitter substances E umami savory amino acids 1 eg Glutamate or MSG 2 MSG creates tingly sensation on tongue Anatomy of mouth III A Taste is predominantly a function of the tongue the pharynx palate and epiglottis also contribute B Nasal cavity palate tongue pharynx epiglottis C Tongue 1 papillae visible to naked eye each has from 1 100 s of taste buds a papillae contain taste buds which are conglomeration of taste cells range in number of taste buds 2 taste pore on surface of tongue exposed to mouth contents a where substances dissolved in saliva interact with taste cells b any taste stimuli accesses taste cell through this pore 3 each taste bud has 50 150 taste cells a taste cells have about 2 week lifespan 4 a person typically has 2000 5000 taste buds 5 tongue isn t divided into different regions that receive specific taste info receptors are all over tongue Taste cells A Taste stimuli depolarize taste cells 1 The membrane potential of taste cells changes depolarizes when activated by appropriate substance 2 90 of taste cells respond to 2 or more basic tastes 3 cells are broadly tuned but some are more selective 4 depolarization transmitter release can fire APs under certain conditions B Salt and sour taste stimuli interact with ion channels on taste cells 1 Salt pathway Na2 conc must be high 10mM to taste it a Salt sensitive cells have Na selective channels b Na channel is always open voltage insensitive c Inc Na in mouth leads to inc Na influx through Na channel d This depolarizes the cell causing Ca2 influx through voltagesensitive Ca2 cells e Transmitter is released 2 Sour pathway sour taste due to acidity H ions a Acids dissolve in water producing H ions b Sour sensitive cells have Na and K channels c H ions enter cells through Na channels d H binds to and blocks K channels e Blocking K channels reduces K efflux f H actions via Na and K channels depolarize cells g Ca2 influx through voltage sensitive Ca2 channels h Transmitter is released C Bitter sweet and umami substances bind to GPCRs 1 GPCRs G protein coupled receptors 2 Binding to GPCRs initiates intracellular signaling effects IV a G proteins stimulate enzyme called phospholipase C b Phospholipase C produces inositol triphosphate IP3 c Leads to metabolic change within cell 3 Na influx into taste cells via Na channels a IP3 opens type of Na channels unique to taste cells b Na influx depolarizes taste cells c IP3 activates unique Na cells that only respond to IP3 and causes Ca release from intracellular storage sites 4 Inc Ca concentration inside taste cell a Ca influx via voltage sensitive Ca channels b IP3 triggers release of Ca from intracellular Ca storage sites 5 Transmitter release stimulates axons in cranial nerves a Both sources of calcium trigger transmitter release b Transmitter is adenosine triphosphate ATP 6 GPCRs made of one of more protein subunits a T1R and T2R genes encode for taste protein subunits b Different genes encode for bitter sweet and umami GPCRs c Bitter receptors i 30 different types ii these receptor types compromise the family of T2R proteins iii different once can detect poisonous substances d Sweet receptors i Only one type ii Two subunits formed from two T1R proteins ie T1R2 and T1R3 e Umami receptors i Formed from two T1R proteins ii T1R1 and T1R3 f Bitter sweet and umami proteins in different cells Taste pathway to brain A Taste information is carried by 3 cranial nerves to the brainstem 1 Anterior 2 3 of tongue and palate send axons into cranial nerve VII a Cranial nerve VII attached to tongue 2 Posterior 1 3 of tongue send axons into cranial nerve IX a Cranial nerve IX attached to back of tongue 3 Throat regions glottis epiglottis pharynx send axons into cranial nerve X a Cranial nerve X attached to back of throat B Taste stimulus preference