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Special Senses

Special Senses. Dr. N. Matthew Ellinwood, D.V.M., Ph.D. April 7, 2014. Iowa State University College of Agriculture and Life Sciences. Olfaction. Dogs: Tested sensitivity to 10 parts per billion Dogs as cancer detectors (88-99% accurate) Used in disaster and emergency situations

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Special Senses

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  1. Special Senses Dr. N. Matthew Ellinwood, D.V.M., Ph.D. April 7, 2014 Iowa State University College of Agriculture and Life Sciences

  2. Olfaction • Dogs: Tested sensitivity to 10 parts per billion • Dogs as cancer detectors (88-99% accurate) • Used in disaster and emergency situations • Examples of situations where dogs are used include: Disaster searches, water searches, cadaver searches,area searches, trailing searches,snow/avalanche searches, forensic searches • Used as police dogs for things such as bomb and drug detection • Dogs are used to track criminals, lost persons, lost pets • Have ability to follow scents that are days old http://www.nasdak9.org/scullyvest.jpg

  3. For more information about search/rescue dogs… • www.cadaverdog.com • http://www.nasar.org/nasar/specialty_fields.php http://www.aboutxinjiang.com

  4. Overview • Olfaction • Taste

  5. Olfaction • Chemoreception • A quality shared with the sense of taste • Odorants • Chemicals of specific size and shape • Binding of odorants to receptors form the basis of olfaction

  6. Olfactory Anatomy

  7. Receptors, Odorants, and Olfaction • Each receptor senses just one kind of odorant • Receptor cilia bathed in a lipid mucous • Binding of odorant results in propagation of an action potential • Olfactory recptor cells turn over about every 40 days.

  8. Sensitivity of Olfaction • Size of the epithelium • Density of the epithelium • Variety of different receptors expressed • Controlled at the genetic level • Each population of distinct receptors is express from a specific gene

  9. Sensitivity of Olfaction • Size of the epithelium • Humans = 10 cm2 versus canine = 170 cm2 • Density of the epithelium • Canine 100X > than Human • Variety of different receptors expressed • Controlled at the genetic level • Olfactory receptors: the largest gene family • Each population of distinct receptors is express from a specific gene • Number of genes similar in dogs and humans • >60% of human genes are non-functional, versus <20% of canine genes

  10. Overall Canine Sensitivity • Results in potentially 100,000,000 more sensitive than humans

  11. Accessory Olfactory Reception • Vomeronasal organ • Located in the nose • Senses pheromones • Important in reproduction • Limited repertoire • Flehman response • A contraction of the muscles around the nose and mouth to increase air delivery to this structure • Seen in males and females around females in heat

  12. Flehman

  13. Central Processing of Odor Detection • Nerve impulses processed in and propagated from the olfactory bulb • Neural projections extend from the olfactory bulb to the limbic system and the hippocampus • Controls emotions (limbic system) • Memory (hippocampus)

  14. Role of Olfaction in Taste • Taste repertoire is very limited • Salt (low to non-existent in cats) • Sweet (very limited in cats) • Sour • Bitter • Umami • Odor is what gives us the rich sense of taste • Exhalation is the most important aspect of olfaction delivery involved in taste

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