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Name: Date: House: Teacher: Day One: Introduction DO NOW Directions: The ancient Greek warrior, Achilles, was nearly immortal after being dipped in the River Styx as a child. However, he was held by his heel, and this left his heel as the only weak point of his body. Indeed, it was an arrow to this heel that finally brought his life to an end, and this area of the human body has been named the Achilles tendon. Why do you think the Achilles tendon is such an important part of the body? Without a working tendon, no muscles attached to the bone can function. Mr. Shah’s 7th Grade Science Class | Page 1 TALK LIKE A SCIENTIST Muscle: Tendon: Fiber-like cells which contract to move skeletal bones Ends of muscles which connect muscles to bones I DO: Muscle Cells Directions: Use the diagram above to answer the questions below about muscle cells. 1. Based on its location, what is the function of the endomysium? It contains the skeletal muscle fibers. 2. Based on its location, what is the function of the perimysium? It contains the muscle fascicles. 3. Based on its location, what is the function of the epimysium? It envelopes the muscle. 4. Based on its location, what is the function of a tendon? It connects the muscle to a bone. 5. Why are there blood vessels near the muscle? It provides muscle cells with oxygen. 6. Why are there nerves near the muscle? It transmits motor signals to the muscle cells. Mr. Shah’s 7th Grade Science Class | Page 2 WE DO: Actin and Myosin Muscles can be subdivided into units called sarcomeres, groups of muscle fascicles that have different types of fibers which can move alongside one another in order to expand and contract the muscle as a whole. These are made up of thin filaments called actin, which are attached to the ends of the sarcomeres, which move together over thick filaments called myosin. When the actin move closer together over the myosin, the muscle is contracted. This takes a lot of energy, so the muscle cells are filled with tons of mitochondria, ready to break down glucose in cellular respiration and produce energy in the form of ATP. Normally, this leaves behind a molecule called pyruvate. However, while exercising, when there isn’t enough oxygen going to our cells, the pyruvate ferments into lactic acid, a chemical which, when built up, causes our muscles to feel pained and fatigued. Directions: List three things your body does while exercising to increase the amount of oxygen going to your blood cells and prevent lactic acid fermentation from happening: Increased breathing rate to inhale more oxygen Increased blood flow to pump oxygen to body cells via blood Increased sweat to balance body temperature against increased heart rate Mr. Shah’s 7th Grade Science Class | Page 3 YOU DO: Contractions Directions: Organize information about the types of muscle contractions in the table below. Contraction Description Example Isometric Joint angle and muscle length do not change during contraction, so that contraction takes place in a static position. Pushing a stalled car Isotonic Joint angle and muscle length change during contraction, so that contraction is dynamic. Pumping a bike tire Concentric Muscles shorten while generating force due to the force of the muscles being greater than the force being exerted upon. Lifting a rowing oar Eccentric Muscles elongate while under tension due to an opposing force greater than the force of the muscles. Setting down a bag Mr. Shah’s 7th Grade Science Class | Page 4 Name: Date: House: Teacher: EXIT TICKET Directions: What chemical might be found in position X? A. Glucose B. Lactic Acid C. Actin D. Myosin Directions: What kind of muscle contraction is being shown in the image above? A. Isometric B. Isovelocity C. Concentric D. Eccentric Mr. Shah’s 7th Grade Science Class | Page 5