Question | Answer |
Surrounds entire muscle | Epimysium |
Surrounds each muscle fiber | Endomysium |
Surrounds each muscle bundle (fascicle) | Perimysium |
Binds muscles into functional groups | Deep fascia |
Plasma membrane of skeletal muscle fiber | Sarcolemma |
Cytoplasm of a skeletal muscle fiber | Sarcoplasm |
Series of membranous channels (modified ER) that surround each myofibril | Sarcoplasmic reticulum |
Rod-like contractile elements within a muscle fiber | Myofibril |
Functional unit of a skeletal muscle fiber | Sarcomere |
Area of the sarcomere with overlapping thick and thin filaments | A band |
Area of the sarcomere containing only thin filaments | I band |
Area in the center of the A band containing only thick filaments | H band |
Cross-bridges | Myosin molecules |
Contains vesicles filled with acetylcholine | Synaptic knob |
Space between the neuron and the muscle | Synaptic cleft |
Contains receptors for acetylcholine | Motor end plate |
Type of contraction represented by a single stimulus/contraction/relaxation sequence | Twitch |
A muscle producing peak tensions with visible relaxation during rapid cycles of contraction and relaxation | Incomplete tetanus |
A muscle that is stimulated so frequently that the relaxation phase is completely eliminated | Complete tetanus |
When a muscle is stimulated repeatedly for several seconds with a constant stimulus, the amount of tensions gradually increases to a maximum | Wave summation |
Activities best suited for slow oxidative fibers | Endurance-type activities |
Activities best suited for fast oxidative fibers | 400M or 800M sprint |
Activities best suited for fast glycolytic fibers | Short-term intense movements |
Single, very long cylindrical, multinucleate cells with striations | Skeletal muscle fibers |
Branching chains of cells; uni- or binucleate striations; intercalated discs | Cardiac muscle cells |
Single, fusion, uninucleated; no striations | Smooth muscle cells |
Ability to receive and respond to a stimulus | Excitability |
Ability to shorten forcibly when adequately stimulated | Contractility |
Ability to be stretched or extended | Extensibility |
Ability of a muscle to resume its resting length after being stretched | Elasticity |
Propagation of an electrical current along the sarcolemma | Action potential |
The initial polarized state | Resting potential |
Restoration of membrane potential to resting potential | Repolarization |
The time when fiber cannot stimulated until repolarization is complete | Refractory period |
Neurotransmitter released into the neuromuscular junction | Acetylcholine |
Enzyme released into neuromuscular junction to break down acetylcholine | Acetylcholinesterase |
Released by terminal cisternae into the sarcoplasm to bind with troponin | Ca2+ |
Protein found in SR that binds calcium | Calsequestrin |
Protein that works alternately with calsequestrin | Calmodulin |
Electrical event occurring only at neuromuscular junction | End plate potential |
Electrical event spreading in all directions from neuromuscular junction across the sarcolemma | Action potential |
Membrane charge prior to depolarization | Resting (polarized) potential |
Time between the stimulus and an action potential initiation | Latent period |
Outside positive relative to the inside | Electrical conditions of a resting sarcolemma |
Production of an end plate potential at the motor end plate and consequent depolarization of adjacent areas | Depolarization and generation of action potential |
Increased positive charge inside sarcolemma changes permeability of adjacent areas, opening voltage-regulated Na+ channels | Propagation of the action potential |
Change in sarcolemma after the wave of depolarization; Na+ channels close and K+ channels open, allowing K+ to create a positive charge outside the membrane | Repolarization |
Pulling on something to change its position | Producing movement |
Development of tension to prevent movement as in keeping the vertebral column upright. | Maintaining posture |
Attaching to bones and keeping them in close proximity to one another. | Stabilizing joints |
Release of energy during metabolism | Generation of heat |
Changes shape during the contraction cycle | Myosin |
Slides toward the M line during a contraction. | Actin |
Covers the binding site. | Tropomyosin |
Binds Ca2+ and starts the contraction cycle | Troponin |