Hi, this is Kate from MinuteEarth.
When you get an infection, your body will often get to work generating extra heat - which
we know as “a fever” - to help you fight the pathogen.
Which seems logical; after all, we also heat raw food, questionable water, and used surgical
equipment to literally sizzle pathogens to death.
But that’s not how a fever works.
I mean...even the puniest strategies for killing germs with heat require temperatures of around
65 degrees Celsius, yet most fevers top out at 40 degrees or so; any temperature that’s
hot enough to decimate an invasion of viruses or bacteria would also decimate your own cells.
A few extra degrees can slow down the replication of certain pathogens, but the bigger effect
of a fever is how it benefits our own bodies.
When your body temperature rises, neutrophils - white blood cells that lurk in your bone
marrow - wake up and start gobbling germs, and other germ-gobblers get better at identifying
and engulfing pathogens when your temp is higher.
Then there are T cells, which travel to lymph nodes to identify the pathogen - but they
have to get there quickly, before the germ overwhelms your body; when your body heats
up, T cells get there way faster and can coordinate an effective response in time.
But why does heat - and not even that much heat - have all these effects?
The answer, paradoxically, may have to do with the dangers of too much heat.
If you’re, say, jogging in the summer and you start to overheat, delicate components
inside you can start breaking down.
So as your temperature rises, your body jumps into action to protect itself.
For instance, cells churn out tons of “heat shock proteins,” which find molecules that
are unraveling and bind to them, either to stabilize or re-ravel them.
When you get an infection, a fever may work - at least in part - by actively increasing
your body temperature in order to trigger this same kind of protective process.
Your body churns out those same heat shock proteins, which are so good at finding and
binding to all sorts of molecules.
They bind to the tails of T cells - and then bind several T cells’ tails together - helping
the cells clump up, grab blood vessel walls, and make the trek to the lymph nodes, where
they ID the invader and coordinate a response.
Heat shock proteins can also recognize and bind to specific bits of pathogens - sometimes
to the heat shock proteins the pathogens themselves have churned out - then transport them to
waiting germ-gobblers.
Our ancestors first co-opted these existing protective mechanisms to help fend off infections
as long as 600 million years ago, and animals have been turning up the heat on pathogens
ever since.
Even critters that can’t regulate their body temperature internally will bask, buoy,
or buzz until they’re toasty - and infection-free.
And no matter what species you are, the strategy works; infected individuals that boost their
temps recover more quickly - and more often - than those that don’t.
So the next time you get a fever, make sure you give it a warm welcome.
The human body is an amazing thing - we could go on and on about it.
And we actually have…we made MinuteBody, an entire series of videos about the weird
workings of, well, us.
You can check out the first season exclusively on Nebula, a platform built by independent
education-y creators like us as a place to experiment and try out new ideas.
And now CuriosityStream - a documentary streaming service that loves supporting creators - has
teamed up with Nebula to launch the second season of MinuteBody; the newest episode - about
the helpful bacteria on your Skin - comes out today!
As part of our partnership, when you sign up for CuriosityStream at curiositystream.com/minuteearth,
you’ll also get Nebula for free.
So for just fifteen bucks a year, you'll not only get access to CuriosityStream's huge
library of high quality content like "Out Of The Cradle", you’ll also get free access
to tons of creative stuff on Nebula from the folks behind TierZoo, Polyphonic, Extra Credits
- and all new episodes of MinuteBody.
Come check it out!