Question | Answer |
Skeletal Muscle: Terminology | Fibers, myofilaments, myofibril, sacrolemma, and sacroplasm |
Skeletal Muscle: Terminology:
Fibers | cells of skeletal and smooth muscle tissue |
Skeletal Muscle: Terminology:
Myofilaments | -special type of microfilaments CONTRACTILE PROTEINS that shorten muscle cells
-ACTIN and MYOSIN |
Skeletal Muscle: Terminology:
Myofibril | -A complex ORGANELLE composed of bundles of myofilaments
-Each muscle fiber contains 100 to 1000 of these than run parallel to its length
-Account for 80% of cellular volume in a muscle cell |
Skeletal Muscle: Terminology:
Sarcolemma | plasma membrane of the muscle cell |
Skeletal Muscle: Terminology:
Sarcoplasm | -Cytoplasm of the muscle cell
-GLYCOSOMES and MYOGLOBIN |
Skeletal Muscle: Epimysium | -"Outside the muscle"
-An overcoat of dense irregular connective tissue that surrounds the entire muscle
-May blend with deep fascia between muscles |
Skeletal Muscle: Perimysium | -"Around the Muscle"
-Fibrous connective tissue that surrounds groups of muscle fibers call fascicles |
Skeletal Muscle: Endomysium | -"Within the muscle"
-Fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiber (cell) |
Skeletal Muscle: Microscopic Anatomy
Sacroplasmic Reticulum Definition | -Interconnecting tubules of endoplasmic reticulum that surround each myofibril |
Skeletal Muscle: Microscopic Anatomy
Sarcoplasmic Reticulum Function | -store and regulate intracellular levels of Calcium (Ca2+)
-Calcium is released when a muscle fiber is stimulated to contract |
Skeletal Muscle: Microscopic Anatomy
Sarcoplasmic Reticulum:
TERMINAL CISTERNAE | -Sac like regions of the Sarcoplasmic Reticulum that contains calcium ions
-perpencdicular to the myofibril |
Skeletal Muscle: Microscopic Anatomy:
Sarcomere | - The smallest contractile unit within a myofibril
-Aligned end to end along a myofibril |
Skeletal Muscle: Microscopic Anatomy: Sarcomere:
TITIN | large protein in sarcomere that resists overstretching by holding the thick filament in place |
Skeletal Muscle: Microscopic Anatomy: Sarcomere:
Striation Pattern | -Repeating series of dark A bands and light I bands |
Skeletal Muscle: Sarcomere: Striation Pattern:
A Band | thick and thin filaments overlap |
Skeletal Muscle: Sarcomere: Striation Pattern:
I Band | region with only thin filaments |
Skeletal Muscle: Sarcomere: Striation Pattern:
Z Line | -defines the boundaries of each sacromere
-where thin filaments from adjacent sacromeres attach |
Skeletal Muscle: Sliding Filament Model of Contraction | -Myosin heads bind to thin filaments and bend, then detach and repeat several times during contraction, acting like a ratchet to generate tension and propel thin filaments to the center of the sacromere
-As this occurs in sarcomeres, THE MUSCLES SHORTE |
Skeletal Muslcle: Sliding Filament Model of Contraction:
Initiation | -proces is initiated by the binding of calcium ions to the thin filaments and powered by ATP |