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39 Cards in this Set
- Front
- Back
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A connective tissue sheath that surrounds skeletal muscle.
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epimysium
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A loose connective tissue that suround muscle fasciculi.
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perimysium
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loose connective tissues that surround muscle cells or muscle fibers.
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endomysium
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the cytoplasm within a muscle cell.
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sarcoplasm
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threadlike structures that extend from one end of the muscle fiber to the other.
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myofibril
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2 types of protein fibers that make up myofibrils.
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actin and myosin
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actin and myosin arranged into highly ordered repeating units along the myofibril.
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sarcomeres
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A network of portein fibers forming an attachment site for actin myofilaments.
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Z disk
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molecules that are attached at a specific interval along the actin myofilaments and provide calcium-binding sites on the actin myofilament.
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troponin
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located along the groove between the twisted strands of actin myofilament subunits.
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tropomyosin
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cell membrane of the muscle fiber.
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sarcolemma
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tube-like invaginations along the surface of the sarcolemma that are located at regular intervals along the muscle fiber.
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T tubules
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a highly organized, smooth endoplasmic reticulum.
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sarcoplasmic reticulum
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consists of only actin myofilaments and spans each Z disk and ends at the myosin myofilaments.
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I band
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a dark, central region in each sarcomere that extends the length of the myosin myofilaments.
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A band
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a light zone in the center of each sarcomere which consists of only myosin myofilaments.
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H zone
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a dark-staining band that anchors the myosin myofilaments in the center of the sarcomere.
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M line
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the charge difference between the outside of the muscle cell membrane and the inside.
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resting membrane potential
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the decrease in the difference in potential (charge) between 2 points, as between the inside and outside of a cell membrane.
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depolarization
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the rapid depolarization and repolarization of the cell membrane.
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action potential
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visible bundles of muscle.
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muscle fasciculi
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nerve cells along which action potentials travel to skeletal muscle fibers.
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motor neurons
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a junction between a nerve cell and another nerve cell, muscle cell, or gland cell.
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synapse
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a single motor neuron and all the skeletal muscle fibers it innervates.
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motor unit
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an enlarged axon terminal.
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presynaptic terminal
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the space between the presynaptic terminal and the muscle fiber membrane.
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synaptic cleft
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the muscle fiber membrane
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postsynaptic membrane
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small vesicles within each presynaptic terminal.
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synaptic vesicles
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a molecule released by a presynaptic nerve cell that stimulates or inhibits a postsynaptic cell.
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neurotransmitter
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an enzyme that breaks down acetylcholine that is released into the synaptic cleft between neurons and muscle fibers.
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acetylcholinesterase
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an autoimmune disorder in which antibodies are formed against acetylcholine receptors.
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myasthenia gravis
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the sliding of actin myofilaments past myosin myofilaments during contraction.
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sliding filament model
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the exposed attachment sites on the actin myofilaments that bind to the heads of the myosin myofilaments.
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cross-bridges
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the time between the application of a stimulus and the beginning of a contraction in a muscle twitch.
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lag phase
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the time of contraction in a muscle twitch.
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contraction phase
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the time during which the muscle relaxes in a muscle twitch.
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relaxation phase
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involves increasing the force of contraction of the muscle fibers within the muscle.
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summation
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involves increasing the number of muscle fibers contracting.
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recruitment
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a sustained contraction that occurs when the frequency of stimulation is so rapid that there is no relaxation.
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tetanus
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