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Chapter 6:
The Muscular System
| Term | Definition |
|---|---|
| Endomysium | A delicate connective tissue sheath that encloses each muscle fiber |
| Perimysium | A coarser fibrous membrane that wraps several sheathed muscle fibers |
| Fascicle | A bundle of fibers |
| Epimysium | Tough “overcoat” of connective tissue that bind many fascicles |
| Tendons | Strong, cordlike blend of the epimysia (dense fibrous tissue attaching a muscle to bone) |
| Aponeuroses | Strong, sheetlike blend of the epimysia (fibrous or membranous connecting a muscle and the part it moves) |
| Intercalated Discs | Special junctions that joint branching cells (cardiac muscle fibers) |
| Muscular System | Organ system consisting of skeletal muscles and their connective tissue attachments |
| Sarcolemma | Plasma membrane that many oval nuclei can be seen just beneath |
| Myofibrils | Long ribbonlike organelles which nearly fill the cytoplasm and push the nuclei aside |
| Sarcomeres | Tiny contractile units --- aligned end-to-end like boxcars in a train along the length of the myofibrils |
| Myofilaments | Two types of threadlike protein within each of out "boxcar" sacomeres |
| Thick Filaments | Myosin filaments --- made mostly of bundled molecules of the protein myosin, but they also contain ATPase enzymes, which split ATP to generate the power for muscle contraction |
| Cross Bridges | Projections or myosin heads when they link the thick and thin filaments together during contraction |
| Thin Filaments | Actin filaments --- Composed of the contractile protein called actin, plus some regulatory proteins that play a role in allowing (or preventing) myosin head-binding to actin |
| Sarcoplsmic Reticulum (SR) | Another very important muscle fiber organelle --- a specialized smooth endoplasmic reticulum |
| Motor Unit | One neuron and all the skeletal muscle cells it stimulates |
| Axon | Nerve fiber --- a long threadlike extension of the neuron that reaches the muscle and branches into a number of axon terminals |
| Axon Terminals | Each forms junctions with the sarcolemma of a different muscle cell |
| Neuromuscular Junctions | The junctions that are formed between the axon terminals and the sarcolemma |
| Synaptic Cleft | The gap between the nerve endings and the muscle cells' membranes that is filled with tissue (interstitial) fluid |
| Neurotransmitter | A chemical that is released when the nerve impulse reaches the axon terminals |
| Acetylcholine (ACh.) | The specific neruotransmitter that stimulates skeletal muscle cells |
| Action Potential | An electrical current |
| Creatine Phosphate (CR) | The unique high-energy molecule that is found in muscle fibers but not other cell types |
| Aerobic Respiration | Occurs in the mitochondria and involves a series of metabolic pathways that use oxygen |
| Anaerobic Respiration | Occurs in the mitochondria and involves a series of metabolic pathways that do not use oxygen |
| Isotonic Contractions | “Same tone”/tension --- the myofilaments are successful in their sliding movements, the muscle shortens, and movement occurs |
| Isometric Contractions | “Same measurement”/length --- the myofilaments are “skidding their wheels,” and the tension in the muscle keeps increasing --- trying to slide =, but the muscle is pitted against some more or less immovable object |
| Muscle Tone | The state of continuous partial contractions |
| Prime Mover | The muscle that has the major responsibility for causing a particular movement |
| Antagonists | Muscles that oppose or reverse a movement |
Created by:
sarah23me1
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