How does The Dogs Nose know?

How Does The Dog’s Nose Know?
This article is the first in a series to introduce the readers to the specifics of canine olfaction. A number of parts will be presented to cover various topics including: canine vs human olfactory systems, does breed or sex affect sense of smell, the accessory olfactory system, factors that affect the sense of smell and an introduction to the genetics of olfaction. If there are any other areas readers wish to be covered, please get in touch.
So to start off the series, What Is Olfaction?
Olfaction is also known as the sense of smell. The olfactory system comprises of the nose, which contains specially adapted cells designed for the detection of odours. These are then linked to a specific part of the brain, known as the olfactory bulb, via nerves. When odour molecules enter the nose, the cells send signals via the nerves to the brain where this information is interpreted.IMG_0483

Image from http://www.biologyjunction.com/olfaction.htm
There are two theories for the mechanism of olfaction; the “lock and key” theory and the vibration theory. These two theories will now be briefly described.
Lock and Key Theory
This is also known as “shape theory” was first proposed in 1949 and is based on the notion that for a smell to be detected, an odour molecule must fit into a receptor on a cell. Only a molecule of a specific size, shape and configuration will fit into a particular receptor to induce a signal to the brain. A modernised version of this theory based on findings from scientific research is known as the odotope or “weak shape” theory. However, similar shaped molecules can often give rise to very different smells which confuses this theory somewhat.
Vibration Theory
This was first proposed in 1928 but was abandoned in favour of the “lock and key” theory. However, a 1996 research paper resurrected the idea. This posits that a molecule must first fit into a receptor on a cell but will only trigger a signal if the molecule has the correct vibrational frequency. However, research testing this theory has so far proven inconclusive.IMG_0484

Image from http://www.sciencefocus.com/feature/health/how-we-smell-competing-theories
Neither of these theories completely explains the phenomenon of olfaction. And so the exact mechanism remains a mystery. The next part in the series will explore the differences between the canine and human olfactory systems in an attempt to explain why the dog’s sense of smell is superior to our own.

For more information on the theories of olfaction, please visit the following websites:
http://www.physics.org/featuredetail.asp?id=83
http://www.bbc.co.uk/bang/article_smell.shtml
http://theconversation.com/whats-that-smell-a-controversial-theory-of-olfaction-deemed-implausible-42449
http://rsta.royalsocietypublishing.org/content/368/1924/3491

References:
Turin L (1996). A spectroscopic mechanism for primary olfactory reception. Chemical senses. 21 (6): 773–91
Moncrieff, Robert Wighton (1949), What is odor? A new Theory. American Perfumer, 54: 453
Buck, L. and Axel, R. (1991) A novel multigene family may encode odorant receptors: a molecular basis for odor recognition. Cell, 65, 175-187.

 

k9WH are grateful to their ‘resident’ scientist for this article.

You May Also Like

123 thoughts on “How does The Dogs Nose know?

  1. Pingback: Buy viagra in us
  2. Pingback: cialis from india
  3. Pingback: cialis 5 mg
  4. Pingback: cialis 20mg price
  5. Pingback: cialis price
  6. Pingback: Order viagra
  7. Pingback: is cialis generic
  8. Pingback: buy levitra
  9. Pingback: viagra 100mg
  10. Pingback: viagra 100mg
  11. Pingback: viagra pills
  12. Pingback: ed pills otc
  13. Pingback: best ed medication
  14. Pingback: tadalafil generic
  15. Pingback: viagra for men
  16. Pingback: Viagra or cialis
  17. Pingback: Viagra or cialis
  18. Pingback: vardenafil 10 mg
  19. Pingback: levitra 10mg
  20. Pingback: levitra dosage
  21. Pingback: viagra cheap
  22. Pingback: cash advance
  23. Pingback: personal loan
  24. Pingback: viagra for sale
  25. Pingback: cialis buy
  26. Pingback: cialis 5 mg
  27. Pingback: buy cialis
  28. Pingback: cialis generic
  29. Pingback: 20 cialis
  30. Pingback: viagra 25mg
  31. Pingback: real online casino
  32. Pingback: casino real money
  33. Pingback: casino online
  34. Pingback: buy generic viagra
  35. Pingback: order viagra
  36. Pingback: viagra connect
  37. Pingback: online viagra
  38. Pingback: viagra pills
  39. Pingback: generic viagra
  40. Pingback: order viagra
  41. Pingback: cheap viagra
  42. Pingback: cheap viagra
  43. Pingback: buy viagra online
  44. Pingback: Viagra 130 mg usa
  45. Pingback: tadalafil buy
  46. Pingback: viagra generic
  47. Pingback: cialis price
  48. Pingback: buy Viagra 100 mg
  49. Pingback: buy viagra
  50. Pingback: rx trust pharm
  51. Pingback: Cialis 20mg usa
  52. Pingback: Cialis 60mg online
  53. Pingback: Cialis 20 mg usa
  54. Pingback: sildenafil
  55. Pingback: cheap viagra
  56. Pingback: amaryl 2mg otc
  57. Pingback: viagra buy
  58. Pingback: levitra cialis
  59. Pingback: buy cialis
  60. Pingback: avapro 300mg cheap
  61. Pingback: buy viagra nyc
  62. Pingback: baclofen 10mg uk

Comments are closed.