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Muscle Contraction Skeletal Muscle Anatomy Review: Skeletal muscles are composed of highly organized skeletal muscle cells. These cells are commonly referred to as muscle fibers. Inside muscle fibers are bundles of protein fibers referred to as myofibrils. Each myofibril is a collection of protein filaments called myofilaments. These myofilaments are arranged into repeating functional units called sarcomeres. The function of a muscle cell is to contract or shorten, each cell does so by the thin filaments sliding past the thick filaments. Questions: On the sarcomere diagram label the thin and thick filaments. How many sarcomeres are shown in the above diagram? Label each sarcomere. Using the locations of the thin and thick filaments describe the following: A Band I Band H Zone Z Line M Line Zone of Overlap 4.Describe how the A Band, H Zone, and Zone of Overlap differ from each other. 5.Before you Google it, guess how many sarcomeres you think are found in your Sartorius muscle (the longest muscle in the human body). Your hypothesis: Look up how many sarcomeres are in the Sartorius muscle. How close were you? Resting vs Contracted Sarcomeres Questions: 6.Label the A Bands, I Bands, H Zones, and Zones of Overlap on the images above. 7. Measure the length of these structures in mms and record the data in the chart below. Structure Length in Resting Sarcomere Length in Contracted Sarcomere Change in Length Thin Filament Thick Filament A Band I Band H Zone Zone of Overlap Sarcomere 8.Based on the data you collected, describe what is happening during muscle contraction. 9.Again using the data and diagrams above, describe why there is a limited amount of shortening that can occur in a sarcomere during muscle contraction. 10.In your own words, based on the activities above, describe the sliding filament theory for muscle contraction.