1. Muscular System Video Skit Script<br />(Mark trying to work out)<br />Alex: You’re never going to get abs or biceps like that<br />Won Hee: Yeah man, that's pathetic. We’ll tell you a bit about the muscular system<br />Alex: Ok, so muscles are tissues composed of fibers and cells. They cover up 40% of your body.<br />Won Hee: That’s right. Also, there are different types of muscles: cardiac muscles, skeletal muscles, smooth muscles, voluntary muscles, and involuntary muscles. You need to know how muscles work too.<br />Alex: Cardiac muscles are found in the walls of the heart. They are striated, meaning they are striped.<br />Won Hee: Everyday, cardiac muscle contract about 70 times per minute.<br />Mark: Wow, that's a lot.<br />Alex: We know Mark. You can just listen to us as we explain.<br />Won Hee: Anyways, cardiac muscle is needed throughout our life.<br />Alex: Without it, we would die. If the cardiac muscle stops, we can’t live.<br />Mark: Oh. . .But that’s the heart. What about the other parts? I don’t really care about the heart. I want to know about biceps and abs.<br />Won Hee: Cardiac muscle is really important. You should care about it. And we’ll get to other parts later.<br />Alex: Yeah, we’ll tell you after lunch.<br />(After Lunch)<br />Mark: Ok tell me about other muscles. I already know about the cardiac muscle.<br />Won Hee: Do you even remember anything about it?<br />Mark: YES. The cardiac muscle is striated and contracts 70 times per minute every day. If it stops, we can’t live.<br />Alex: Pretty good. Now we’ll tell you about skeletal muscles.<br />Won Hee: So skeletal muscles move bones. They are the most common type of muscles. <br />Alex: Thick bands of tissue called tendons attach the muscles to bones. Skeletal muscles are striated, just like the cardiac muscle. Do you even remember what “striated” means?<br />Mark: Yeah, of course. It means that they are connected with other muscles.<br />Won Hee: Yeah Mark, you’re totally right. (sarcastic)<br />Mark: Yeah, I’m so smart<br />Alex: You don’t even know sarcasm is. You really don’t remember? Striated means striped.<br />Mark: Yeah I knew that…<br />Won Hee: We believe you man (sarcastic). Moving on, skeletal muscles are striated, and they contract and tire more easily.<br />Alex: Ok, so that’s it for today and we’ll tell you more about different types of muscles tomorrow.<br />(Next day)<br />Mark: Tell me more about muscles.<br />Alex: Ok. You need to know about smooth muscles.<br />Won Hee: Unlike skeletal muscles and the cardiac muscle, smooth muscles are not striated. Just as its name says, it's smooth.<br />Alex: Smooth muscles can be found in your intestines, bladder, blood vessels, and other internal organs.<br />Mark: Oh. And didn't you guys say something about voluntary and involuntary muscles? What are those?<br />Won Hee: Voluntary muscles are muscles that you can control, and involuntary muscles are muscles that you cannot control.<br />Mark: But how do muscles work?<br />Alex: Muscles work in pairs. When one contracts, the other relaxes. <br />Won Hee: Yeah. And muscles always pull. They never push. When you bring your leg up, the muscles in the back of your thigh contract and the muscles in the front relax and lengthen.<br />Alex: And when you make your leg straight again, the muscles on the front of your thigh contract and the muscles in the back of your thigh relax and lengthen.<br />Mark: And how do I get biceps and abs?<br />Won Hee: You have to exercise them a lot. The number of muscle cells increase and the size of the muscles change.<br />Alex: It's also because individual muscle cells get bigger.<br />Won Hee: If you don't exercise your muscles, they get softer and smaller.<br />Alex: How muscles move is important too. Muscles need energy.<br />Won Hee: Yeah, when muscles contract, energy is released and it becomes mechanical and thermal energy.<br />Alex: Mechanical energy is movement and thermal energy is warmth.<br />Won Hee: When the energy is used up, your muscles become tired. <br />Alex: Yeah. And thermal energy is what keeps your body temperature constant.<br />Won Hee: So that's the muscular system.<br />Alex: I hope you learned a lot from our teachings Mark.<br />Mark: Yeah, I did. Thanks guys. I'm going to properly work out now.<br />Examples of mechanical devices that work like muscles:<br />A crane<br />The strings on a drafting lamp<br />A fire truck ladder<br />The End<br />