1 00:00:01,710 --> 00:00:13,310 Hey there! 2 00:00:13,310 --> 00:00:17,370 I'm sure you know, like Squeaks here does, that exercise is a really important part of 3 00:00:17,370 --> 00:00:19,550 keeping your body healthy and strong. 4 00:00:19,550 --> 00:00:22,929 And whether you're running, a race, playing football, or just doing a whole bunch of jumping 5 00:00:22,929 --> 00:00:25,670 jacks, exercise means moving! 6 00:00:25,670 --> 00:00:30,870 And one SciShow Kids viewer named Autumn wants to know, how does my body move? 7 00:00:30,870 --> 00:00:32,369 Really awesome question, Autumn! 8 00:00:32,369 --> 00:00:36,469 Your body is made up of lots of different parts that all have very special jobs. 9 00:00:36,469 --> 00:00:40,689 To help keep things organized, scientists sometimes group the parts of our bodies into 10 00:00:40,689 --> 00:00:43,030 what we call body systems. 11 00:00:43,030 --> 00:00:47,530 And all of the parts in a certain body system work together to accomplish a goal. 12 00:00:47,530 --> 00:00:52,189 When it comes to making you move, it takes three body systems working together to get 13 00:00:52,189 --> 00:00:53,189 the job done. 14 00:00:53,189 --> 00:00:57,090 They're called the muscular system, the skeletal system, and the nervous system. 15 00:00:57,090 --> 00:00:58,090 Ready to check them out? 16 00:00:58,090 --> 00:01:00,270 Let's start with the muscular system. 17 00:01:00,270 --> 00:01:03,810 Your muscular system is made of, well, muscles. 18 00:01:03,810 --> 00:01:08,150 Muscle is the stuff, what scientists call tissue, that allows you to move around. 19 00:01:08,150 --> 00:01:11,849 Muscles don't just help you to swing a bat or jump to catch a ball. 20 00:01:11,849 --> 00:01:17,950 Some muscles help you chew, wiggle your nose, stick out your tongue, or even blink. 21 00:01:17,950 --> 00:01:22,569 And some muscles, like the ones in your back and legs, just help to hold your body upright 22 00:01:22,569 --> 00:01:25,209 so you can walk, run, or simply sit. 23 00:01:25,209 --> 00:01:29,530 Muscle tissue is pretty flexible, kind of like thick rubber or elastic. 24 00:01:29,530 --> 00:01:32,329 And also like rubber, it can stretch and change shape. 25 00:01:32,329 --> 00:01:33,329 Let's see how. 26 00:01:33,329 --> 00:01:38,530 When you bend your arm at the elbow, a muscle called your bicep contracts, or squeezes, 27 00:01:38,530 --> 00:01:39,530 together. 28 00:01:39,530 --> 00:01:42,390 When it contracts, its shape gets shorter and thicker. 29 00:01:42,390 --> 00:01:45,409 When you straighten your arm, your bicep relaxes. 30 00:01:45,409 --> 00:01:48,609 When a muscle relaxes, its shape gets longer and thinner. 31 00:01:48,609 --> 00:01:52,569 But muscles contracting and relaxing aren't enough to make us move. 32 00:01:52,569 --> 00:01:55,810 They need to be attached to another part of our body to get the job done. 33 00:01:55,810 --> 00:01:58,890 And that's where the next system, the skeletal system, comes in. 34 00:01:58,890 --> 00:02:03,450 The main part of your skeletal system, the skeleton, is made of all your hard, sturdy 35 00:02:03,450 --> 00:02:04,450 bones. 36 00:02:04,450 --> 00:02:07,810 Although we sometimes think of skeletons as dead things, especially around Halloween, 37 00:02:07,810 --> 00:02:09,750 that's actually not true. 38 00:02:09,750 --> 00:02:12,370 Your bones are very much alive, and they have many jobs. 39 00:02:12,370 --> 00:02:17,210 One of the most important jobs is to support or hold up the rest of your body, and this 40 00:02:17,210 --> 00:02:18,750 includes your muscles. 41 00:02:18,750 --> 00:02:22,129 Strong cords called tendons attach your muscles to your bones. 42 00:02:22,129 --> 00:02:26,469 When a muscle contracts or relaxes, it pulls the bone into a different position, which 43 00:02:26,469 --> 00:02:27,469 makes it move. 44 00:02:27,469 --> 00:02:30,229 But how do your muscles know they're supposed to move at all? 45 00:02:30,229 --> 00:02:33,689 Well, they know because they're under control of your nervous system. 46 00:02:33,689 --> 00:02:37,069 The most important part of your nervous system is your brain. 47 00:02:37,069 --> 00:02:39,650 Your brain is kind of like your body's command center. 48 00:02:39,650 --> 00:02:43,409 When you decide to move, your brain sends signals to your muscles, giving them specific 49 00:02:43,409 --> 00:02:45,090 instructions on what to do. 50 00:02:45,090 --> 00:02:46,909 Say you're trying to pick up a snack. 51 00:02:46,909 --> 00:02:50,449 Your brain sends signals to the muscles in your hand and wrist, telling some of them 52 00:02:50,449 --> 00:02:51,449 to contract. 53 00:02:51,449 --> 00:02:56,729 As the muscles contract, they pull the bones in your fingers so that you can grab the apple. 54 00:02:56,729 --> 00:03:00,569 Then your brain sends more signals to your arm muscles, telling them to move the bones 55 00:03:00,569 --> 00:03:03,870 in your arm so that you can bring the apple right to your mouth. 56 00:03:03,870 --> 00:03:05,310 Snack accomplished! 57 00:03:05,310 --> 00:03:09,889 So it takes the actions of three body systems to help us move — the muscular, skeletal, 58 00:03:09,889 --> 00:03:11,169 and nervous systems. 59 00:03:11,169 --> 00:03:15,090 Autumn, thanks for watching SciShow Kids and asking such a great question! 60 00:03:15,090 --> 00:03:18,629 And if anyone else has a question for any of us here at the Fort, let us know by leaving 61 00:03:18,629 --> 00:03:22,969 a comment or emailing us at kids at the sideshow.com. Thanks guys. See you later.