1. Skeletal Muscle Microscopic Anatomy Chapter 10

2. Microscopic Anatomy Muscle fibers = muscle cells: long and multinucleate Sarcolemma: cell membrane myoglobinSarcoplasm: cytoplasm; rich in oxygen-storing myoglobin protein

3. Myofibrils: bundles of contractile proteins; fill most of the cytoplasm; 100’s to 1000’s per cell Sarcomeres: the repeating functional unit of contraction in each myofibril

4. Sarcoplasmic reticulum (smooth ER): stores Ca ++ (muscle contraction begins when stored Ca ++ ions are released into sarcoplasm) Mitochondria: provide ATP for contraction T tubules (transverse tubules): narrow tubes that are continuous with sarcolemma, conduct impulses

7. Closer Look at Myofibril Composition thin filaments: actin (plus tropomyosin & troponin) thick filaments: myosin Fig. 10.5

8. Sarcomere Structure sarcomeresZ lines: the boundary between sarcomeres A band: overlap of thick (myosin) filaments & thin (actin) filaments I band: thin (actin) filaments only H zone: thick (myosin) filaments only Fig. 10.3