Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain
Speaker 1: stuff is Christian saga. Here. There are lots of ways
Speaker 1: to numb yourself to the minor aches and pains that
Speaker 1: we humans accrue in our daily lives. But today we're
Speaker 1: talking about aspirin. Why aspirin because although aspirin as we
Speaker 1: know it has only existed since the late eighteen hundreds,
Speaker 1: the plant that it was originally derived from, willow, is
Speaker 1: probably the oldest known pain killer in history. Records of
Speaker 1: people using willow leaves to relieve pain and fevers stretch
Speaker 1: back six thousand years to ancient Assyria and sumer Willow
Speaker 1: was also put to use in ancient Egypt, Babylon, and China,
Speaker 1: and Hippocrates thought it was pretty rad especially for pain
Speaker 1: during childbirth. In the seventeen and eighteen hundreds, scientists were
Speaker 1: on identifying, extracting, and purifying the active ingredient in willow,
Speaker 1: which turned out to be a chemical they called salison,
Speaker 1: which they further discovered your digestive system changes into salacilic acid,
Speaker 1: which is what reacts with stuff in your body to
Speaker 1: relieve pain, reduced fever, and swelling. More on how all
Speaker 1: that works in a second, but first salacilic acid. It
Speaker 1: was a pharmacological superstar. German chemists figured out how to
Speaker 1: synthesize it on an industrial scale in the eighteen seventies,
Speaker 1: effectively ending millennia of willow powder use. But it had
Speaker 1: its drawbacks. Lots of patients couldn't stomach it. Literally, it
Speaker 1: was really hard on the stomach lining The son of
Speaker 1: one such patient, a chemist with Friedrich Bear in Company
Speaker 1: by the name of Felix Hoffman, thought it might be
Speaker 1: less irritating if it was less acidic, so Hoffman converted
Speaker 1: it to what Bayer in Company dubbed aspirin in eighteen
Speaker 1: ninety nine. Aspirin has become the popular and less ridiculous
Speaker 1: to pronounce name for Hoffman's chemical compound, a setal silic
Speaker 1: acid or salicylate. It works, as humanity finally figured out
Speaker 1: in the nineteen seventies, by preventing yourselves from using cyclo
Speaker 1: oxygen ase to to create prostaglandins. And don't worry, I'm
Speaker 1: about to unpack all of those words. Let's start with
Speaker 1: the idea that lots of pain is useful evolutionarily speaking,
Speaker 1: when you feel pain due to an injury like a burn,
Speaker 1: or a twisted ankle. It prompts you to take your
Speaker 1: hand away from that hot thing real quick, or to
Speaker 1: keep your weight off the ankle until it heals. It's
Speaker 1: it's useful, right. Pain from an injury to anything but
Speaker 1: the nervous system is called non susceptive pain after specialized
Speaker 1: sense areene neurons located throughout your body called NA susceptors.
Speaker 1: They alert your brain to damage with the help of
Speaker 1: the damaged tissue itself. Cells in the hurt areas start
Speaker 1: producing enzymes that work together to create a few signal chemicals,
Speaker 1: including those prostaglandins I mentioned a minute ago. Prostaglandins tell
Speaker 1: your NO susceptors, no, hey, seriously, there is a problem here.
Speaker 1: They make your NO susceptors increase the signal to your brain.
Speaker 1: You feel the pain more acutely now. Prostaglandins are also
Speaker 1: one of the chemicals that cause inflammation in the tissue
Speaker 1: around a wound. They make your blood vessels expand, flooding
Speaker 1: the damaged tissue with all the immune systems stuff your
Speaker 1: body sends to protect the wound from infection and to
Speaker 1: help it to heal. All of this is great right
Speaker 1: up until it isn't. After a certain point, you don't
Speaker 1: need continual acute pain as a reminder that you're injured.
Speaker 1: We know, and some non susceptive pain and swelling is
Speaker 1: warning us about stimuli that we can't easily avoid, like headaches, arthritis,
Speaker 1: or period cramps. In the case of arthritis, that inflammation
Speaker 1: can even cause more damage in the long run. Here's
Speaker 1: where aspirin swoops in to save the day. When you
Speaker 1: take aspirin, it's absorbed by your digestive tract into your
Speaker 1: blood stream, which takes it throughout your body, including places
Speaker 1: where cells are excreting the enzymes necessary to produce prostaglandins.
Speaker 1: Molecules of aspirin lock up with one of those enzymes,
Speaker 1: cyclo oxygenase two. Once a molecule of cyclo oxygenase two
Speaker 1: is locked into a molecule of aspirin, it can't help
Speaker 1: create prostaglandins, which means fewer prostaglandins, which means that the
Speaker 1: pain signals to your brain don't increase as much and
Speaker 1: the tissue in the area doesn't swell as much. Hey,
Speaker 1: thanks thousands of years of science. Check out the Brainstuff
Speaker 1: channel on YouTube and for more on this, and thousands
Speaker 1: of other topics. Visit how stuff works dot com.