Olfactory receptor neuron - wikipedia Olfactory receptor neuron Olfactory receptor neuron Labels in German. `` Zellen '' = `` cell '', `` riech '' = `` smell '', `` Riechnerv '' = olfactory nerve, `` cillien '' = cilia. Details Location olfactory epithelium in the nose Morphology Bipolar sensory receptor Function Detect traces of chemicals in inhaled air ( sense of smell ) Neurotransmitter Glutamate Presynaptic connections None Postsynaptic connections Olfactory bulb Identifiers Code TH H3. 11.07. 0.01003 NeuroLex ID Olfactory receptor neuron TH H3. 11.07. 0.01003 Anatomical terminology ( edit on Wikidata ) Plan of olfactory neurons. An olfactory receptor neuron ( ORN ), also called an olfactory sensory neuron ( OSN ), is a transduction cell within the olfactory system. Contents 1 Vertebrates 1.1 Structure 1.2 Function 1.3 Desensitization of olfactory neuron 1.4 Number of distinguishable odors 2 Insects 3 See also 4 References 5 External links Vertebrates Humans have about 10 million olfactory receptor neurons. In vertebrates, ORNs are bipolar neurons with dendrites facing the external surface of the cribriform plate with axons that pass through the cribriform foramina with terminal end at olfactory bulbs. The ORNs are located in the olfactory epithelium in the nasal cavity. The cell bodies of the ORNs are distributed among all three of the stratified layers of the olfactory epithelium. Structure Many tiny hair - like cilia protrude from the olfactory receptor cell 's dendrite into the mucus covering the surface of the olfactory epithelium. The surface of these cilia is covered with olfactory receptors, a type of G protein - coupled receptor. Each olfactory receptor cell expresses only one type of olfactory receptor ( OR ), but many separate olfactory receptor cells express ORs which bind the same set of odors. The axons of olfactory receptor cells which express the same OR converge to form glomeruli in the olfactory bulb. Function ORs, which are located on the membranes of the cilia have been classified as a complex type of ligand - gated metabotropic channels. There are approximately 1000 different genes that code for the ORs, making them the largest gene family. An odorant will dissolve into the mucus of the olfactory epithelium and then bind to an OR. ORs can bind to a variety of odor molecules, with varying affinities. The difference in affinities causes differences in activation patterns resulting in unique odorant profiles. The activated OR in turn activates the intracellular G - protein, GOLF ( GNAL ), adenylate cyclase and production of cyclic AMP ( cAMP ) opens ion channels in the cell membrane, resulting in an influx of sodium and calcium ions into the cell, and an efflux of chloride ions. This influx of positive ions and efflux of negative ions causes the neuron to depolarize, generating an action potential. Desensitization of olfactory neuron Desensitization of olfactory neuron The olfactory receptor neuron has a fast working negative feedback response upon depolarization. When the neuron is depolarizing, the CNG ion channel is open allowing sodium and calcium to rush into the cell. The influx of calcium begins a cascade of events within the cell. Calcium first binds to calmodulin to form CaM. CaM will then bind to the CNG channel and close it, stopping the sodium and calcium influx. CaMKII will be activated by the presence of CaM, which will phosphorylate ACIII and reduce cAMP production. CaMKII will also activate phosphodiesterase, which will then hydrolyze cAMP. The effect of this negative feedback response inhibits the neuron from further activation when another odor molecule is introduced. Number of distinguishable odors A widely publicized study suggested that humans can detect more than one trillion different odors. This finding has however been disputed. Critics argued that the methodology used for the estimation was fundamentally flawed, showing that applying the same argument for better - understood sensory modalities, such as vision or audition, leads to wrong conclusions. Other researchers have also showed that the result is extremely sensitive to the precise details of the calculation, with small variations changing the result over dozens of orders of magnitude, possibly going as low as a few thousand. The authors of the original study have argued that their estimate holds as long as it is assumed that odor space is sufficiently high - dimensional. Insects Main article : insect olfaction See also Chemoreceptor Sensory receptor References Jump up ^ Berkowicz, D.A. ; Trombley, P.Q. ; Shepherd, G.M. ( 1994 ). `` Evidence for glutamate as the olfactory receptor cell neurotransmitter ''. Journal of Neurophysiology. 71 ( 6 ) : 2557 -- 61. PMID 7931535. Jump up ^ Vermeulen, A ; Rospars, J.P. ( 1998 ). `` Dendritic integration in olfactory sensory neurons : A steady - state analysis of how the neuron structure and neuron environment influence the coding of odor intensity ''. Journal of computational neuroscience. 5 ( 3 ) : 243 -- 66. PMID 9663551. Jump up ^ Schacter, Daniel L. ( 2014 ). Psychology. p. 167. ISBN 1464106037. Jump up ^ Cunningham, A.M. ; Manis, P.B. ; Reed, R.R. ; Ronnett, G.V. ( 1999 ). `` Olfactory receptor neurons exist as distinct subclasses of immature and mature cells in primary culture ''. Neuroscience. 93 ( 4 ) : 1301 -- 12. doi : 10.1016 / s0306 - 4522 ( 99 ) 00193 - 1. PMID 10501454. Jump up ^ McEwen, D. P ( 2008 ). `` Olfactory cilia : our direct neuronal connection to the external world ''. Curr. Top. Dev. Biol. 85 : 333 -- 370. doi : 10.1016 / S0070 - 2153 ( 08 ) 00812 - 0. Jump up ^ Touhara, Kazushige ( 2009 ). `` Insect Olfactory Receptor Complex Functions as a Ligand - gated Ionotropic Channel ''. Annals of the New York Academy of Sciences. 1170 : 177 -- 80. Bibcode : 2009NYASA1170... 177T. doi : 10.1111 / j. 1749 - 6632.2009. 03935. x. PMID 19686133. Jump up ^ Bieri, S. ; Monastyrskaia, K ; Schilling, B ( 2004 ). `` Olfactory Receptor Neuron Profiling using Sandalwood Odorants ''. Chemical Senses. 29 ( 6 ) : 483 -- 7. doi : 10.1093 / chemse / bjh050. PMID 15269120. Jump up ^ Fan, Jinhong ; Ngai, John ( 2001 ). `` Onset of Odorant Receptor Gene Expression during Olfactory Sensory Neuron Regeneration ''. Developmental Biology. 229 ( 1 ) : 119 -- 27. doi : 10.1006 / dbio. 2000.9972. PMID 11133158. Jump up ^ Bradley, J ; Reuter, D ; Frings, S ( 2001 ). `` Facilitation of calmodulinmediated odor adaptation by cAMP - gated channel subunits ''. Science. 294 : 2176 -- 2178. doi : 10.1126 / science. 1063415. PMID 11739960. Jump up ^ Wei, J ; Zhao, AZ ; Chan, GC ; Baker, LP ; Impey, S ; Beavo, JA ; Storm, DR ( 1998 ). `` Phosphorylation and inhibition of olfactory adenylyl cyclase by CaM kinase II in Neurons : a mechanism for attenuation of olfactory signals ''. Neuron. 21 : 495 -- 504. doi : 10.1016 / s0896 - 6273 ( 00 ) 80561 - 9. PMID 9768837. Jump up ^ Yan, C ; Zhao, AZ ; Bentley, JK ; Loughney, K ; Ferguson, K ; Beavo, JA ( 1995 ). `` Molecular cloning and characterization of a calmodulin - dependent phosphodiesterase enriched in olfactory sensory neurons ''. Proc Natl Acad Sci USA. 92 : 9677 -- 9681. doi : 10.1073 / pnas. 92.21. 9677. Jump up ^ Bushdid, C. ; Magnasco, M.O. ; Vosshall, L.B. ; Keller, A. ( 2014 ). `` Humans Can Discriminate More than 1 Trillion Olfactory Stimuli ''. Science. 343 ( 6177 ) : 1370 -- 2. Bibcode : 2014Sci... 343.1370 B. doi : 10.1126 / science. 1249168. PMC 4483192. PMID 24653035. Jump up ^ Meister, Markus. `` On the dimensionality of odor space ''. eLife. 4. doi : 10.7554 / eLife. 07865. Jump up ^ Gerkin, Richard C. ; Castro, Jason B. `` The number of olfactory stimuli that humans can discriminate is still unknown ''. eLife. 4. doi : 10.7554 / eLife. 08127. Jump up ^ http://www.biorxiv.org/content/biorxiv/early/2015/07/06/022103.full.pdf External links Wikimedia Commons has media related to Olfactory receptor neurons. NIF Search - Olfactory receptor neuron via the Neuroscience Information Framework Insect olfaction Anatomy of smell Microanatomy Epithelium glands mucosa Sustentacular cell Tufted cell Olfactory nerve : 1 ° neuron Olfactory receptor neurons ( Olfactory receptor ) → Olfactory bulb ( Glomeruli ) Olfactory nerve : 2 ° neuron Mitral cells → Olfactory tract → Olfactory trigone Lateral olfactory stria / Primary olfactory cortex Piriform cortex EC - hippocampus system Entorhinal cortex Hippocampal formation Prepyriform area Periamygdaloid cortex Stria medullaris → Habenular nuclei Amygdala → Stria terminalis → Hypothalamus Medial forebrain bundle → Hypothalamus Medial olfactory stria Anterior olfactory nucleus Nervous tissue CNS Tissue Types Grey matter White matter Projection fibers Association fiber Commissural fiber Lemniscus Funiculus Fasciculus Nerve tract Decussation Commissure Neuropil Meninges Cell Types Neuronal Pyramidal Purkinje Granule Glial insulating : Myelination : Oligodendrocyte other Astrocyte Radial glial cell Ependymal cells Tanycyte Microglia PNS General Dorsal Root Ganglion Ramus Ventral Root Ramus Ramus communicans Gray White Autonomic ganglion ( Preganglionic nerve fibers Postganglionic nerve fibers ) Connective tissues Epineurium Perineurium Endoneurium Nerve fascicle Neuroglia Myelination : Schwann cell Neurolemma Myelin incisure Node of Ranvier Internodal segment Satellite glial cell Neurons / nerve fibers Parts Soma Axon hillock Axon Telodendron Axon terminals Axoplasm Axolemma Neurofibril / neurofilament Dendrite Nissl body Dendritic spine Apical dendrite / Basal dendrite Types Bipolar Unipolar Pseudounipolar Multipolar Interneuron Renshaw Afferent nerve fiber / Sensory neuron GSA GVA SSA SVA fibers Ia or Aα Ib or Golgi or Aα II or Aβ and Aγ III or Aδ or fast pain IV or C or slow pain Efferent nerve fiber / Motor neuron GSE GVE SVE Upper motor neuron Lower motor neuron α motorneuron β motorneuron γ motorneuron Termination Synapse Electrical synapse / Gap junction Chemical synapse Synaptic vesicle Active zone Postsynaptic density Autapse Ribbon synapse Neuromuscular junction Sensory receptors Meissner 's corpuscle Merkel nerve ending Pacinian corpuscle Ruffini ending Muscle spindle Free nerve ending Nociceptor Olfactory receptor neuron Photoreceptor cell Hair cell Taste bud Retrieved from `` https://en.wikipedia.org/w/index.php?title=Olfactory_receptor_neuron&oldid=796906239 '' Categories : Chemoreceptor cells Olfactory system Neurons Signal transduction Hidden categories : Medicine infobox template using GraySubject or GrayPage Talk Contents About Wikipedia Čeština 日本 語 Português Edit links This page was last edited on 23 August 2017, at 19 : 21. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: where are the olfactory receptor neurons are located
Answer: olfactory system