Here’s a question for you: how many different scents
do you think you can smell, and maybe even identify with accuracy? 100? 300? 1,000? One study estimates that humans can
detect up to one trillion different odors. A trillion. It’s hard to imagine, but your nose has the molecular
machinery to make it happen. Olfactory receptors — tiny scent detectors — are packed into your nose, each one patiently waiting
to be activated by the odor, or ligand, that it’s been assigned to detect. It turns out we humans,
like all vertebrates, have lots of olfactory receptors. In fact, more of our DNA is devoted
to genes for different olfactory receptors than for any other type of protein. Why is that? Could olfactory receptors
be doing something else in addition to allowing us to smell? In 1991, Linda Buck and Richard Axel
uncovered the molecular identity of olfactory receptors — work which ultimately
led to a Nobel Prize. At the time, we all assumed that these receptors
were only found in the nose. However, about a year or so later, a report emerged of an olfactory
receptor expressed in a tissue other than the nose. And then another such report emerged, and another. We now know that these receptors
are found all over the body, including in some pretty
unexpected places — in muscle, in kidneys, lungs and blood vessels. But what are they doing there? Well, we know that olfactory receptors
act as sensitive chemical sensors in the nose — that’s how they mediate
our sense of smell. It turns out they also act
as sensitive chemical sensors in many other parts of the body. Now, I’m not saying that your liver can
detect the aroma of your morning coffee as you walk into the kitchen. Rather, after you drink
your morning coffee, your liver might use an olfactory receptor to chemically detect
the change in concentration of a chemical floating
through your bloodstream. Many cell types and tissues in the body
use chemical sensors, or chemosensors, to keep track of the concentration
of hormones, metabolites and other molecules, and some of these chemosensors
are olfactory receptors. If you are a pancreas or a kidney and you need a specialized chemical sensor that will allow you to keep track
of a specific molecule, why reinvent the wheel? One of the first examples of an olfactory receptor
found outside the nose showed that human sperm
express an olfactory receptor, and that sperm with this receptor
will seek out the chemical that the receptor responds to — the receptor’s ligand. That is, the sperm
will swim toward the ligand. This has intriguing implications. Are sperm aided in finding the egg by sniffing out the area
with the highest ligand concentration? I like this example
because it clearly demonstrates that an olfactory receptor’s primary job
is to be a chemical sensor, but depending on the context, it can influence how you perceive a smell, or in which direction sperm will swim, and as it turns out, a huge variety of other processes. Olfactory receptors have been
implicated in muscle cell migration, in helping the lung to sense
and respond to inhaled chemicals, and in wound healing. Similarly, taste receptors once thought
to be found only in the tongue, are now known to be expressed
in cells and tissues throughout the body. Even more surprisingly, a recent study found that the light receptors in our eyes
also play a role in our blood vessels. In my lab, we work on trying to understand the roles
of olfactory receptors and taste receptors in the context of the kidney. The kidney is a central
control center for homeostasis. And to us, it makes sense that a homeostatic
control center would be a logical place to employ chemical sensors. We’ve identified a number
of different olfactory and taste receptors in the kidney, one of which, olfactory receptor 78, is known to be expressed
in cells and tissues that are important
in the regulation of blood pressure. When this receptor is deleted in mice, their blood pressure is low. Surprisingly, this receptor
was found to respond to chemicals called
short-chain fatty acids that are produced by the bacteria
that reside in your gut — your gut microbiota. After being produced
by your gut microbiota, these chemicals are absorbed
into your bloodstream where they can then
interact with receptors like olfactory receptor 78, meaning that the changes
in metabolism of your gut microbiota may influence your blood pressure. Although we’ve identified a number
of different olfactory and taste receptors in the kidney, we’ve only just begun
to tease out their different functions and to figure out which chemicals
each of them responds to. Similar investigations lie ahead
for many other organs and tissues — only a small minority of receptors
has been studied to date. This is exciting stuff. It’s revolutionizing our understanding
of the scope of influence for one of the five senses. And it has the potential
to change our understanding of some aspects of human physiology. It’s still early, but I think we’ve picked up on the scent
of something we’re following. (Laughter) Thank you. (Applause)

77 thoughts on “You smell with your body, not just your nose | Jennifer Pluznick”

  1. "Assigned to Detect." EXACTLY! The CREATOR "assigned" them. It is beyond stupidity to think otherwise…
    Atheist Attack… BEGIN!

  2. we are all stinky, what a surprise. This is a waste of human space, no wonder they still owe student loans.

  3. I have clients who certainly smell with their whole bodies. It's like they've never heard of a shower.

  4. That pun at the end was… wait for it… a stinker!

    Hey TED this was fun and fascinating. Thanks for sharing!

  5. Wow, chemical sensors all over our internal organs. You don't say! Of course we need something like that, of course we need feedback on internal changes. However, it's interesting, how exactly it all works.

  6. At first, I thought, "Oh, that's cool." *click*… "What are those receptors doing?" *insert bad pun*… "WHOOOOAH"

  7. Not surprising for me… a nasty chemical build up I had once in my leg produced a sensation I can only describe as being that the blood in my leg started to taste bad. It was definitely taste, but it was in the blood vessels of my leg.

  8. Absolutely fascinating but I'd like apologise on behalf of humanity for the crass ignorance of some of the comments posted here.

  9. Wow, that is interesting and it makes total sense too. GREAT TALK – thank you for this knowledge! I really appreciate it.

  10. Nice but next time try not to wear something that makes you look like you're spiraling uncontrollably into a depression

  11. So our body has "sensors" to detect chemicals. What's new there? This surly is old news, the fact that they are similar, if not identical to ones found in the nose is not surprising. Nature would not use different systems to do what is essentially the same task. We evolved from single-cells organisms, where, if it works, it works and is carried on throughout the evolution of the creatures. This must really be old news, or some mug is paying the team for repetition. But then, that's natures way, it must've worked the first time someone talked about the subject.

  12. What's the difference between an olfactoric and a taste sensor? Both react to ligand binding and I'm pretty sure that I can taste some smells, when they are intense, or should I say smell with my tongue?

  13. "Excuse me? I fragrantly waft with my body, I'll have you know! Maybe YOU smell with your body but that's just because you don't use deodorant!" –typical sort of didn't-even-watch-the-video comment on every youtube video everywhere

  14. When I went through Army boot camp and had to go into the CS gas chamber, we were all in our charcoal suits and gas masks; I farted and only the drill could smell it. So gas masks really do work.

  15. Fascinating, Instructive, engrossing. ,Jennifer I'd like to submit my application to join your team. To read your papers, help in research especially the boring published references. Quite a woman, quite a field.

  16. Waw, and I am Honoured and Happy that we have a Creator that takes care of all us. We are truly enriched with The God of Abraham, Isaac, Israel and the Messiah. Waw.

  17. As I Know we have a barorecepter for regulation the blood pressure. Баро-рецепторы для давления.

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