1 00:00:02,040 --> 00:00:07,080 Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff, 2 00:00:07,080 --> 00:00:09,840 Speaker 1: I'm Lauren vocal Bam, and I've got another brain Stuff 3 00:00:09,920 --> 00:00:13,520 Speaker 1: classic episode for you today from our former host, Christian Sager. 4 00:00:13,920 --> 00:00:22,400 Speaker 1: The topic why do we Itch? Hey everybody, I'm Christian 5 00:00:22,440 --> 00:00:24,920 Speaker 1: Sager and this is the brain Stuff where I tell 6 00:00:24,960 --> 00:00:28,280 Speaker 1: you about itching. Why do we itch? Why does it 7 00:00:28,320 --> 00:00:32,239 Speaker 1: feel so good to scratch an itch? Well? To answer this, 8 00:00:32,360 --> 00:00:36,160 Speaker 1: we must first turn to one of the body's most unappreciated, 9 00:00:36,320 --> 00:00:40,880 Speaker 1: hardworking organs, the skin. So let's start with your skin, 10 00:00:41,240 --> 00:00:45,960 Speaker 1: the original clothing, your birthday suit. Skin is pretty cool stuff. 11 00:00:46,000 --> 00:00:49,080 Speaker 1: It is your body's largest organ. If you were to 12 00:00:49,120 --> 00:00:51,960 Speaker 1: stretch out the skin of the average adult, you know, 13 00:00:52,120 --> 00:00:54,400 Speaker 1: like if you wanted to make some cool book bindings 14 00:00:54,480 --> 00:00:57,360 Speaker 1: or masks or sheets or whatever, you stretch that out, 15 00:00:57,800 --> 00:01:01,280 Speaker 1: that would cover twenty two square air feet and weigh 16 00:01:01,560 --> 00:01:04,880 Speaker 1: eight pounds. That's about enough to cover the twin bed 17 00:01:05,000 --> 00:01:08,200 Speaker 1: in a creepy Serial Killers apartment. But while it's still 18 00:01:08,240 --> 00:01:11,880 Speaker 1: attached to your body, skin protects you from germs signals. 19 00:01:11,880 --> 00:01:16,160 Speaker 1: The immune system regulates body temperature and allows us to 20 00:01:16,240 --> 00:01:21,080 Speaker 1: experience the crucial sense known as touch, one type of 21 00:01:21,120 --> 00:01:25,800 Speaker 1: nerve ending in particular is responsible for the sensation of itching. Now, 22 00:01:25,840 --> 00:01:28,480 Speaker 1: as it turns out, and itch is just the street 23 00:01:28,600 --> 00:01:33,040 Speaker 1: name for something called paritis. Yet it's difficult to say. 24 00:01:33,480 --> 00:01:37,679 Speaker 1: It is the irritation of skin cells or associated nerve 25 00:01:37,800 --> 00:01:42,920 Speaker 1: cells caused by some external stimuli, like say tickling. Itching 26 00:01:43,200 --> 00:01:46,080 Speaker 1: is a built in defense mechanism that alerts your body 27 00:01:46,120 --> 00:01:49,840 Speaker 1: to the potential of being harmed. Think of that feeling 28 00:01:49,840 --> 00:01:53,440 Speaker 1: you get when an insect crawls along your skin. That's 29 00:01:53,480 --> 00:01:56,160 Speaker 1: your body saying watch out, that bug is out for 30 00:01:56,200 --> 00:02:01,320 Speaker 1: your blood. Now, this itching sensation comes from receptors. Yeah, 31 00:02:01,440 --> 00:02:05,120 Speaker 1: remember the whole paritis thing. That's just as difficult to say, 32 00:02:05,120 --> 00:02:09,000 Speaker 1: But these are specialized nerve endings in your skin. Let's 33 00:02:09,000 --> 00:02:11,920 Speaker 1: stick with this insect example. When the bug lands on 34 00:02:11,960 --> 00:02:14,640 Speaker 1: your skin, it may not bother you at first, but 35 00:02:14,840 --> 00:02:17,440 Speaker 1: soon it will begin to rub back and forth across 36 00:02:17,480 --> 00:02:20,360 Speaker 1: your skin as it walks along looking for the best 37 00:02:20,400 --> 00:02:23,680 Speaker 1: place to bite you. Once the bug scratches your skin, 38 00:02:23,840 --> 00:02:27,440 Speaker 1: surface layer receptors in the dermis of the skin will 39 00:02:27,480 --> 00:02:31,760 Speaker 1: become irritated. In a split second, these receptors send a 40 00:02:31,840 --> 00:02:35,040 Speaker 1: signal through fibers in the skin to your spinal cord 41 00:02:35,320 --> 00:02:38,040 Speaker 1: and then up to the cerebral cortex in your brain. 42 00:02:38,639 --> 00:02:41,600 Speaker 1: The same fibers that send itching signals are also used 43 00:02:41,680 --> 00:02:44,639 Speaker 1: to send pain signals to the brain, which once led 44 00:02:44,760 --> 00:02:47,680 Speaker 1: some scientists to believe that itching was a form of 45 00:02:47,840 --> 00:02:51,799 Speaker 1: light pain. That notion has since been dispelled by research 46 00:02:51,880 --> 00:02:56,600 Speaker 1: which showed that pain and itching illicit opposite responses. Pain 47 00:02:56,720 --> 00:03:00,640 Speaker 1: causes us to withdraw, and itching causes us to scratch. 48 00:03:01,200 --> 00:03:03,920 Speaker 1: As soon as we feel an itch, our first natural 49 00:03:03,960 --> 00:03:07,280 Speaker 1: response is to scratch the spot of the itch with 50 00:03:07,320 --> 00:03:10,919 Speaker 1: our fingernails. The reason for this response is simple, we 51 00:03:10,960 --> 00:03:14,680 Speaker 1: want to remove the irritant as soon as possible. Once 52 00:03:14,720 --> 00:03:17,880 Speaker 1: you've scratched the area of irritation, you are likely to 53 00:03:17,960 --> 00:03:21,720 Speaker 1: feel some relief. When your brain realizes that you've scratched 54 00:03:21,720 --> 00:03:24,760 Speaker 1: away the irritant, The signal being sent to your brain 55 00:03:24,840 --> 00:03:28,320 Speaker 1: that you have an itch is interrupted and therefore no 56 00:03:28,400 --> 00:03:33,079 Speaker 1: longer recognized. Even if you don't remove the irritant, scratching 57 00:03:33,080 --> 00:03:36,600 Speaker 1: will at least cause pain and divert your attention away 58 00:03:36,640 --> 00:03:39,840 Speaker 1: from the itching. The irritant that caused the itching is 59 00:03:40,080 --> 00:03:43,440 Speaker 1: very small, maybe only a few microns in length, so 60 00:03:43,480 --> 00:03:46,800 Speaker 1: it only disturbs a few nerve endings When you use 61 00:03:46,800 --> 00:03:49,800 Speaker 1: your finger nail to scratch the spot where the irritant is, 62 00:03:50,160 --> 00:03:53,560 Speaker 1: you not only remove the irritant, but you irritate a 63 00:03:53,760 --> 00:03:57,800 Speaker 1: lot more nerve endings than the irritant. In many cases, 64 00:03:58,000 --> 00:04:02,280 Speaker 1: an itching sensation can be related to various ailments or diseases, 65 00:04:02,320 --> 00:04:06,840 Speaker 1: from dry skin or poison ivy to more serious life 66 00:04:06,840 --> 00:04:13,240 Speaker 1: threatening internal issues. So if you have continual chronic paritis, 67 00:04:13,600 --> 00:04:16,919 Speaker 1: visit your local medical professional. They should be able to 68 00:04:16,920 --> 00:04:19,600 Speaker 1: help you find a solution, which is great because we 69 00:04:19,680 --> 00:04:22,520 Speaker 1: all know there are a few things worse than an 70 00:04:22,520 --> 00:04:29,200 Speaker 1: itch you can't scratch. Today's episode was written by Ben 71 00:04:29,240 --> 00:04:32,080 Speaker 1: Bolan and produced by Tyler Clang. Check out our online 72 00:04:32,080 --> 00:04:35,200 Speaker 1: shop at t public dot com slash Brainstuff. Every purchase 73 00:04:35,240 --> 00:04:38,159 Speaker 1: supports us directly, and of course, for more on this 74 00:04:38,279 --> 00:04:40,320 Speaker 1: and lots of other topics that will get unto your 75 00:04:40,320 --> 00:04:42,960 Speaker 1: skin in a good way, visit our home planet, how 76 00:04:43,000 --> 00:04:55,279 Speaker 1: stuff works dot com.