BIO201L_LAB MODULE 7_ALL QUESTIONS EXAMINABLE WITH ANSWERS|LATEST 2022/2023 RATED 100%

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Pre-Lab Questions ”1. How do banding patterns change when a muscle contracts?” When the muscle contracts the length of the A bands in the sarcomere do not change but the I bands shorten. ”2.... What is the difference between a muscle organ, a muscle fiber, myofibril and a myofilament? ” Starting with the simplest unit, myofilaments are myosin and actin. Each myofibril is made up of two myofilaments, a thick myosin filament and a thin actin filament. Muscle fibers are also called muscle cells and are composed of myofibrils. The muscle organ is the entirety of these and it consists of skeletal muscle, connective tissue, nervous tissue and vascular tissue. ”3. Outline the molecular mechanism for skeletal muscle contraction. At what point is ATP used and why? ” There is this thing called a cross-bridge cycle that causes the skeletal muscle to contract. When an action potential reaches the sarcolemma, calcium is released from the sarcoplasmic reticulum. The calcium binds to troponin, causing a conformational change in the tropomyosin revealing the myosin binding site on the actin filament. ADP and phosphate releases causing the myosin to change conformation and pull the actin filament along with it, causing the contraction. The ATP is needed to bind to the myosin head so it can release the actin filament and return the muscle to resting condition. ”4. Explain why rigor mortis occurs. ” Rigor mortis occurs after death. Since there is no more ATP being produced calcium cannot be transported back into the sarcoplasmic reticulum and it remains in the environment allowing the myosin and actin to bind and creating the cross bridge and since no ATP is present to allow the myosin to release the actin them the muscle remains in a contracted state and stiffens. . Experiment 1: Tendons and Ligaments Post-Lab Questions ”1. Label the arrows in the slide images below based on your observations from the experiment. ” A- Chondrocytes B- Collagen. C- Collagen fibers. D- Skeletal Muscle fibers E- Nuclei F- Collagen fibers Lab 7 The Muscular System BIO201L Lab 7 The Muscular System BIO201L ”2. How does the extracellular matrix of connective tissues contribute to its function? ” The extracellular matrix of connective tissue contributed by providing protection and support, differentiating between different tissue types and facilitating intercellular communication. ”3. Why are tendons and ligament tissues difficult to heal? ” Tendons and ligaments are difficult to heal because they have very low/minimal blood supply flowing to them . ”4. What difference do you see between the tendon – muscle insertion image and the tendon image? ” The collagen in the tendon muscle image looks wrinkly whereas in the tendon image it was smoother. In the tendon image the fibers seem to all be going in the same direction unlike in the tendon-muscle insertion. I ”5. What differences do you see between the tendon and ligament sections? ” Tendon fibers are arranged in very dense bundles whereas the ligaments are not very densely arranged. There also seem to be a decent amount of collagen fibers present between the skeletal muscle fibers, they aren't as closely packed together. Lab 7 The Muscular System BIO201L Experiment 2: The Neuromuscular Junction Post-Lab Questions ”1. Are there few or many nuclei at the end plate? ” There are a lot of nuclei at the end plate. ”2. What is a motor unit? ” A motor unit is made up of an individual motor neuron and all of the muscle fibers it innervates and they all work together to contract a single muscle. ”3. How is a greater force generated (in terms or motor unit recruitment)? ” Ated by greater force is generated by the branching of motor nerves into muscle fibers that are connected to larger motor units and can create a larger force by recruiting more/larger units. ”4. What types of sensors are present within the muscle to identify how much force is generated? ” The sensors within the muscle that identify how much force is generated are the golgi tendons and the muscle spindles. Experiment 3: Muscle Fatigue Table 2: Experimental Counts Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Predicted Value 18 16 14 12 10 Actual Value 14 14 14 14 14 Post-Lab Questions ”1. How did the predicted results compare to the actual results? ” My logic for my predictions was that as I continued with the trails my muscles would get tired and thus the values would decrease over the number of trials so I started my predictions off at 18 and lowered them. The actual results showed that the trial values remained constant. ”2. Did you notice any changes in the number of repetitions you could perform, or how your hand felt after each of the trials? ” I was able to perform the same number of reps per trial but I did notice that my hand was becoming kind of sore and I was feeling the repetitions more as I went on. ”3. Explain the actions that were occurring at the cellular level to produce this movement. Include sources of energy and any possible effect of muscle fatigue. ” Muscle fatigue occurs when our muscles use up all the ATP and its energy is being depleted. As the test went on I was using up the ATP making each rep harder than the ones before it. Other factors that can affect muscle fatigue are lactic acid accumulation and oxygen depletion. [Show More]

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