1 00:00:02,040 --> 00:00:08,920 Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain 2 00:00:08,960 --> 00:00:11,840 Speaker 1: stuff is Christian saga. Here. There are lots of ways 3 00:00:11,960 --> 00:00:14,720 Speaker 1: to numb yourself to the minor aches and pains that 4 00:00:14,760 --> 00:00:18,880 Speaker 1: we humans accrue in our daily lives. But today we're 5 00:00:18,920 --> 00:00:23,439 Speaker 1: talking about aspirin. Why aspirin because although aspirin as we 6 00:00:23,600 --> 00:00:27,000 Speaker 1: know it has only existed since the late eighteen hundreds, 7 00:00:27,280 --> 00:00:31,360 Speaker 1: the plant that it was originally derived from, willow, is 8 00:00:31,440 --> 00:00:35,680 Speaker 1: probably the oldest known pain killer in history. Records of 9 00:00:35,720 --> 00:00:39,560 Speaker 1: people using willow leaves to relieve pain and fevers stretch 10 00:00:39,640 --> 00:00:44,720 Speaker 1: back six thousand years to ancient Assyria and sumer Willow 11 00:00:45,159 --> 00:00:49,440 Speaker 1: was also put to use in ancient Egypt, Babylon, and China, 12 00:00:49,840 --> 00:00:54,440 Speaker 1: and Hippocrates thought it was pretty rad especially for pain 13 00:00:54,760 --> 00:00:59,880 Speaker 1: during childbirth. In the seventeen and eighteen hundreds, scientists were 14 00:01:00,280 --> 00:01:05,240 Speaker 1: on identifying, extracting, and purifying the active ingredient in willow, 15 00:01:05,280 --> 00:01:08,759 Speaker 1: which turned out to be a chemical they called salison, 16 00:01:09,040 --> 00:01:15,039 Speaker 1: which they further discovered your digestive system changes into salacilic acid, 17 00:01:15,440 --> 00:01:18,000 Speaker 1: which is what reacts with stuff in your body to 18 00:01:18,080 --> 00:01:22,760 Speaker 1: relieve pain, reduced fever, and swelling. More on how all 19 00:01:22,760 --> 00:01:27,000 Speaker 1: that works in a second, but first salacilic acid. It 20 00:01:27,080 --> 00:01:31,440 Speaker 1: was a pharmacological superstar. German chemists figured out how to 21 00:01:31,520 --> 00:01:35,479 Speaker 1: synthesize it on an industrial scale in the eighteen seventies, 22 00:01:35,480 --> 00:01:40,680 Speaker 1: effectively ending millennia of willow powder use. But it had 23 00:01:40,720 --> 00:01:45,600 Speaker 1: its drawbacks. Lots of patients couldn't stomach it. Literally, it 24 00:01:45,680 --> 00:01:48,440 Speaker 1: was really hard on the stomach lining The son of 25 00:01:48,520 --> 00:01:52,520 Speaker 1: one such patient, a chemist with Friedrich Bear in Company 26 00:01:52,560 --> 00:01:55,560 Speaker 1: by the name of Felix Hoffman, thought it might be 27 00:01:55,640 --> 00:01:59,840 Speaker 1: less irritating if it was less acidic, so Hoffman converted 28 00:01:59,840 --> 00:02:04,560 Speaker 1: it to what Bayer in Company dubbed aspirin in eighteen 29 00:02:04,680 --> 00:02:09,960 Speaker 1: ninety nine. Aspirin has become the popular and less ridiculous 30 00:02:09,960 --> 00:02:14,800 Speaker 1: to pronounce name for Hoffman's chemical compound, a setal silic 31 00:02:15,120 --> 00:02:20,440 Speaker 1: acid or salicylate. It works, as humanity finally figured out 32 00:02:20,480 --> 00:02:25,000 Speaker 1: in the nineteen seventies, by preventing yourselves from using cyclo 33 00:02:25,160 --> 00:02:30,480 Speaker 1: oxygen ase to to create prostaglandins. And don't worry, I'm 34 00:02:30,520 --> 00:02:33,400 Speaker 1: about to unpack all of those words. Let's start with 35 00:02:33,480 --> 00:02:37,840 Speaker 1: the idea that lots of pain is useful evolutionarily speaking, 36 00:02:38,240 --> 00:02:41,200 Speaker 1: when you feel pain due to an injury like a burn, 37 00:02:41,320 --> 00:02:44,079 Speaker 1: or a twisted ankle. It prompts you to take your 38 00:02:44,120 --> 00:02:47,080 Speaker 1: hand away from that hot thing real quick, or to 39 00:02:47,160 --> 00:02:49,959 Speaker 1: keep your weight off the ankle until it heals. It's 40 00:02:49,960 --> 00:02:54,120 Speaker 1: it's useful, right. Pain from an injury to anything but 41 00:02:54,320 --> 00:02:59,280 Speaker 1: the nervous system is called non susceptive pain after specialized 42 00:02:59,639 --> 00:03:04,800 Speaker 1: sense areene neurons located throughout your body called NA susceptors. 43 00:03:05,240 --> 00:03:08,040 Speaker 1: They alert your brain to damage with the help of 44 00:03:08,080 --> 00:03:11,840 Speaker 1: the damaged tissue itself. Cells in the hurt areas start 45 00:03:11,880 --> 00:03:16,200 Speaker 1: producing enzymes that work together to create a few signal chemicals, 46 00:03:16,240 --> 00:03:21,519 Speaker 1: including those prostaglandins I mentioned a minute ago. Prostaglandins tell 47 00:03:21,560 --> 00:03:26,000 Speaker 1: your NO susceptors, no, hey, seriously, there is a problem here. 48 00:03:26,320 --> 00:03:29,919 Speaker 1: They make your NO susceptors increase the signal to your brain. 49 00:03:30,400 --> 00:03:35,240 Speaker 1: You feel the pain more acutely now. Prostaglandins are also 50 00:03:35,320 --> 00:03:38,720 Speaker 1: one of the chemicals that cause inflammation in the tissue 51 00:03:38,800 --> 00:03:42,480 Speaker 1: around a wound. They make your blood vessels expand, flooding 52 00:03:42,480 --> 00:03:45,560 Speaker 1: the damaged tissue with all the immune systems stuff your 53 00:03:45,600 --> 00:03:49,800 Speaker 1: body sends to protect the wound from infection and to 54 00:03:49,960 --> 00:03:53,400 Speaker 1: help it to heal. All of this is great right 55 00:03:53,480 --> 00:03:56,000 Speaker 1: up until it isn't. After a certain point, you don't 56 00:03:56,080 --> 00:04:00,400 Speaker 1: need continual acute pain as a reminder that you're injured. 57 00:04:00,640 --> 00:04:04,000 Speaker 1: We know, and some non susceptive pain and swelling is 58 00:04:04,040 --> 00:04:08,760 Speaker 1: warning us about stimuli that we can't easily avoid, like headaches, arthritis, 59 00:04:08,880 --> 00:04:12,800 Speaker 1: or period cramps. In the case of arthritis, that inflammation 60 00:04:12,880 --> 00:04:16,280 Speaker 1: can even cause more damage in the long run. Here's 61 00:04:16,320 --> 00:04:19,720 Speaker 1: where aspirin swoops in to save the day. When you 62 00:04:19,800 --> 00:04:23,640 Speaker 1: take aspirin, it's absorbed by your digestive tract into your 63 00:04:23,640 --> 00:04:27,400 Speaker 1: blood stream, which takes it throughout your body, including places 64 00:04:27,440 --> 00:04:32,880 Speaker 1: where cells are excreting the enzymes necessary to produce prostaglandins. 65 00:04:33,080 --> 00:04:37,280 Speaker 1: Molecules of aspirin lock up with one of those enzymes, 66 00:04:37,560 --> 00:04:42,680 Speaker 1: cyclo oxygenase two. Once a molecule of cyclo oxygenase two 67 00:04:42,880 --> 00:04:46,640 Speaker 1: is locked into a molecule of aspirin, it can't help 68 00:04:46,880 --> 00:04:51,560 Speaker 1: create prostaglandins, which means fewer prostaglandins, which means that the 69 00:04:51,600 --> 00:04:56,000 Speaker 1: pain signals to your brain don't increase as much and 70 00:04:56,080 --> 00:05:00,000 Speaker 1: the tissue in the area doesn't swell as much. Hey, 71 00:05:00,440 --> 00:05:08,400 Speaker 1: thanks thousands of years of science. Check out the Brainstuff 72 00:05:08,480 --> 00:05:10,799 Speaker 1: channel on YouTube and for more on this, and thousands 73 00:05:10,839 --> 00:05:26,920 Speaker 1: of other topics. Visit how stuff works dot com.