Chapter 12: Muscle Tissue 1. What is the gross anatomy of skeletal muscle. Include the epimysium, perimysium, endomysium, fascicles, and myofilaments (thick and thin filaments). Epimysium - fibrous connective tissue that forms tendons/sheaths. Around the skeletal muscle organ. Perimysium - Connective tissue around fascicles. Endomysium - connective tissue around muscle cells (muscle fibers are muscle cells are myofibers) Myofilaments - make up myofibrils thick composed of myosin proteins thin composed of actin proteins as well as troponin and tropomyosin. 2. Describe the microscopic anatomy of a muscle fiber (muscle cell). Include the sarcolemma, T-tubules, sarcoplasmic reticulum, mitochondria, triad. 3. Know the components of sarcomere: A-bands, I-bands, M-line, and Z-disc, H Zone, thick filaments and thin filaments. What happens to each of the components when the muscle cell is relaxed. 1 Sarcomere = Z disc to Z disc. A band is the dark area - mostly thick filaments I band is light - mostly thin filaments and are defined as from one end of an A band to the other including the Z disc H Zone - light area within A band that do not contain any thin filaments. M line - line of proteins in center of A band. When muscle is relaxed, from a contracted state, the titin filament allows the sarcomere to elastically recoil.