Muscles and Bones Gizmo Answer Key

Name: Stella Campbell Date: 10-04-2022 Student Exploration: Muscles and Bones Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: actin, biceps, cartilage, contract, extend, fast twitch fiber, flex, fulcrum, humerus, lever, ligament, muscle fiber, myofibril, myosin, powerstroke, radius, sarcomere, skeletal muscles, slow twitch fiber, tendon, triceps, ulna Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. When you lift a weight, what part of the arm is doing the most work? biceps 2. How do you think your arm muscles cause your forearm bones to move? muscles contract by moving against the skeleton and becoming shorter. They pull on the bones allowing the body to move Gizmo Warm-up In the Muscles and Bones Gizmo, you will learn about the anatomy of the arm. You will build an arm model, then test its ability to lift a dumbbell and throw a ball. You will see how making adjustments to the arm can affect its ability to lift and throw. To begin, make sure you are on the ANATOMY tab, the entire arm is shown, and no circles are open. Select Hide muscles. Click Play. 1. Describe what the arm bones are doing. moving up and down 2. Turn off Hide muscles and turn on Show labels. Describe what the biceps and triceps are doing as the forearm moves up and down. Contrasting and relaxing Activity A: Muscle anatomy Get the Gizmo ready: ● Make sure the ANATOMY tab is selected and no circles are open. Introduction: Your arm contains muscles, bones, and other connective tissue. When muscles contract, they pull on the bones, causing them to move. In this activity, you will learn what causes muscles to contract. Question: What causes muscles to contract? 1. Observe: Turn on Hide muscles and Show labels. A. Which bone connects the shoulder to the forearm? numerus B. What are the names of the two forearm bones? radius and ulna 2. Observe: Note the white connective tissue along the elbow. Cartilage reduces friction between bones. Examine the ligament. A. Ligaments connect bones to other bones B. Turn off Hide muscles. Inspect the tendons. Tendons join bones to muscle bones 3. Explore: Click Play. Observe the muscles as the forearm moves up and down. A. When the arm flexes (bends upward), which muscle contracts? biceps B. Which muscle relaxes when the arm flexes? triceps C. When the arm extends (straightens), which muscle contracts? triceps D. Which muscle relaxes when the arm extends? biceps E. Why do muscles work in pairs? When one muscle contracts, the opposing muscle expands. 4. Observe: Click on the biceps to see a close-up of the muscle. A. What is the muscle made of? muscle fibers B. Click Play. What happens to the muscle fibers (muscle cells) as the arm flexes and extends? contracts 5. Observe: Click on the muscle fiber to see a close-up. Note that each muscle fiber consists of a bundle of still smaller rod-like structures known as myofibrils, which are striated (banded). A. What are the dark bands made of? thick filaments B. What are the light bands made of? thin filaments 6. Observe: Click on the myofibril to see a close-up of a sarcomere. A. What protein are the thick filaments made of? myosin B. What protein are the thin filaments made of? actin C. Click Play. What happens to the thick and thin filaments? they are linked together D. How do these filaments enable muscles to contract and relax? they push the actin forward until the muscle relaxes 7. Explore: Click on the sarcomere to take a closer look at the connection between actin and myosin. Click Play. A. Describe what is occurring. Myosin's ADP enables a powerstroke that moves actin. The action of the myosin heads pulling on the actin filament is called a powerstroke. B. Where does myosin get the energy to perform a contraction? ADP and phosphorus 8. Summarize: Explain how actin and myosin work together to help you lift an object. During muscle contractions, myotibrils are moved by an interaction between actin and myosin. Activity B: Get the Gizmo ready: Arm design: Lifting ● Open the DESIGN tab. ● For the Challenge, select Lift. Question: How can an arm be constructed to lift weights most effectively? 1. Experiment: In this activity, you will custom design an arm to lift a dumbbell using bones, muscles, and connective tissue. Drag pieces from the parts library to the red dots on the left. The arm is complete when all of the red dots are covered. Refer back to the ANATOMY tab if needed. When you are finished, select the TEST tab. A. Click Play. Did the arm lift the dumbbell? no If not, modify your design. B. Which muscle must contract to lift the dumbbell? biceps C. What happens to the length of this muscle when it contracts? shortens 2. Compare: Note the three different options for the ratio of slow twitch fibers to fast twitch fibers. Slow twitch (ST) fibers contract and relax more slowly than fast twitch (FT) fibers. Construct an arm using each of the three muscles, for both the biceps and triceps. Determine the maximum dumbbell mass each arm can lift and record in the table below. Muscle 80% ST, 20% FT 50% ST, 50% FT 20% ST, 80% FT Maximum mass 15 17 24 What type of muscle fiber is best for lifting the most mass? 20% 80% 3. Collect data: Set the dumbbell mass to 10 kg and select Multiple reps. Click Play. A. Record the number of reps each muscle type can do before it is too tired to continue: 80% ST, 20% FT: 17 50% FT, 50% ST: 15 20% ST, 80% FT: 14 B. Which fiber type gets tired the fastest? 20% 80% C. Which type of fiber is best if you need a quick burst of energy? 80% 20% D. Which fiber is best for low intensity, sustained exercise? 50% 50% Muscles made of slow twitch fibers use oxygen and are rich in blood vessels, giving them a dark red color. These fibers produce relatively little force but can last a long time before they get tired because they receive a constant supply of oxygen and fuel. Fast twitch fibers do not need outside oxygen, have fewer blood vessels, and are lighter in color. They can generate large amounts of force and provide a quick burst of energy. However, fast twitch fibers have a very limited supply of fuel and tire quickly. 4. Investigate: In the DESIGN tab, remove the cartilage from one of your designed arms. Compare the number of repetitions this arm can do compared to the arm with cartilage. What do you find? makes faster attempts Since cartilage acts to reduce friction between the bones in a joint, the absence of cartilage forces the muscles to work harder and tire more quickly. Cartilage also prevents joint pain. 5. Experiment: In the DESIGN tab, you can use a slider to adjust the length of the forearm bones. Use the Gizmo to see how bone length affects how much mass can be lifted. A. What do you find? tries more faster and can lift less B. On the TEST tab, for Data select Summary. Note the output. How does the force exerted on the same mass differ between short and long bones? more force on 21 reps The arm acts as a lever, with the elbow serving as the pivot point or fulcrum. As the distance to the fulcrum increases, less weight can be lifted. So while shorter arms can lift more weight, longer arms can lift objects higher. 6. Investigate: In the DESIGN tab, the white circles represent the insertion point of the tendons, where they connect the muscles to the bone. Use the Gizmo to see how the location of the insertion point affects the amount of mass that can be lifted. A. What do you find? the longer the insertion, the longer the arm can lift B. Why do you think the location of the insertion point has this effect? It has the potential to spread farther C. Note how far the arm lifts the weight. What is a disadvantage of moving the insertion point farther from the elbow? the higher the arm can lift In an actual human arm, the insertion point is close to the elbow, allowing for a greater range of motion. 7. Apply: Using the principles you have learned, construct an arm that can lift the most mass. A. How much mass can your arm lift? B. What settings did you use? 56 Forearm length: 0.1 Activity C: Arm design: Throwing Muscle type: 20/80 Insertion point: 0.05 Get the Gizmo ready: ● On the DESIGN tab, set the Length to 0.27 m. ● For the Challenge, select Throw. Question: How can an arm be constructed to throw a ball most effectively? 1. Experiment: In this activity, you will see how arm muscles behave when throwing as opposed to lifting. (Even though other muscles are involved with throwing, we will only look at the upper-arm muscles here.) Construct an arm as before, making Biceps the contracting muscle. Go to the TEST tab, check that the challenge is Throw, and press Play. A. What happened? Ball dropped B. Make the necessary adjustment and throw again. Were you successful? yes C. Why is it necessary for the triceps to be the contracting muscle when throwing? direction of the motion 2. Investigate: For each combination, find the triceps force and baseball velocity, recording data below. Keep mass of ball, insertion point, and length of forearm bones constant. Muscle fiber type 80% ST, 20% FT Triceps force (N) 1084 Baseball velocity (m/s) 10.5 50% ST, 50% FT 1395 11.2 20% ST, 80% FT 1699 11.9 A. Which muscle fiber type generated the greatest force? 20%ST,80%FT B. Which muscle fiber type enabled the fastest throw? 80%ST,20%FT C. Are slow or fast twitch fibers best for throwing fast? 50%ST,50%FT D. Explain your reasoning. faster reflex -> more force and velocity E. Which fiber type do you think is best when making multiple throws? slow 3. Predict: If you were throwing a very light ball, do you think it would be better to have a long or short arm? a short arm since it would be considerably harder and less effective to throw a heavier ball with a smaller arm than one that could make it travel farther. How about when throwing a heavy ball? a bigger arm because the arm might me stronger 4. Experiment: Construct an arm made of 50% FT, 50% ST fibers, for both muscles. Set the forearm length to 0.20 m and throw a 0.10 kg ball. Then, set the forearm length to 0.35 m and throw the same ball. Repeat the procedure with a 3.00 kg ball. Record data below. Forearm bone length (m) Mass of ball (kg) Triceps force (N) Output force (N) Baseball velocity (m/s) 0.20 0.35 0.10 0.10 1395 1395 195 112 9.2 10.3 0.20 0.35 3.00 3.00 1395 1395 195 112 4.5 4 A. Which forearm threw the 0.10 kg ball faster? 0.35 B. Which forearm threw the 3.00 kg ball faster? 0.2 5. Explain: Why do you think the short arm was a little bit better for throwing a heavy ball, and the long arm was slightly better for throwing a light ball? If possible, discuss your answers with your classmates and teacher. The short arm makes it more suitable lifting heavier objects because it can exert greater force and power. Due to the extended arm's increased leverage and wider range, speed is increased. It works better with lightweight things. 6. Apply: Using the principles you have learned, construct an arm that can throw a 0.14-kg baseball the fastest. (Hint: You can also vary the insertion point of the triceps tendon to the forearm.) A. How fast did the arm throw? 15.6 m/s B. What settings did you use? Forearm length: 0.35 Muscle type: 20/80 Insertion point: 0.07