Chapter 8: MuscularSystem – Flashcards
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the bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone
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tendon
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the dense layer of connective tissue that surrounds an entire skeletal muscle
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epimysium
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the nerves and blood vessels that service and individual muscle fiber are located in the connective tissue
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endomysium
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a fascicle is
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a group of muscle fibers that are encased in the perimysium
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the delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent muscle fibers together
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endomysium
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superficial to deep muscle fibers
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epimysium, perimysium, fascicle, endomysium, muscle fiber, myofibril
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a thin layer of connective tissue that surrounds a muscle fascicle is called
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perimysium
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interactions between actin and mysoin filaments of the sacromere are responsible for
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muscle contraction
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the plasma membrane of a skeletal muscle fiber is called
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sacrolemma
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at rest, the tropomysin molecule is held in place by
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troponin molecules
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at rest, active sites on the actin are blocked by
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tropomysoin molecules
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the action potential in skeletal muscle fibers is generated by the
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sacrolemma
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the neuromuscular junction is well-studied example of a chemical synapse. what is the critical event that occurs at the neuromuscular junction
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acetylcholine is released by acon terminals of the motor neuron
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calcium entry into the axon terminal triggers what
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synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine
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acetylcholine binds to its receptor in the sacrolemma and triggers
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the opening of ligand-gated cation channels
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each skeletal muscle fiber is controlled by a motor neuron at a single
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neuromuscular junction
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the narrow space between the synaptic terminal and the muscle fiber is the
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synaptic cleft
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receptors for acetylcholine are located on the
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motor end plate
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triggering of the muscle action potential occurs after
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acetylcholine binds to chemically-gated channels in the end plate membrane
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when acetylcholine binds to receptors at the motor end plate, the end plate membrane becomes
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more permeable to sodium ions
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the cytoplasm of the axon terminals at the neuromuscular junction contains vesicles filled with molecules of
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acetylcholine
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synaptic vesicles contain neurotransmitters that are released by [blank] when the action potential arrives
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exocytosis
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excitation of the sacrolemma is coupled or linked to the contraction of skeletal muscle fiber. what specific event initiates the contraction?
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calcium release from the sacroplasmic reticulum initiates the contraction
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in response to action potentials arriving along the transverse tubules, the sacroplasmic reticulum releases
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calcium ions
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action potential is conduction into a skeletal muscle fiber by
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transverse tubules
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what is a cross bridge?
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a myosin head bound to actin
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what specific event triggers the uncovering of the myosin binding site on actin?
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calcium release channels open in the sacroplasmic reticulum, and calcium levels rise in the sacroplasm
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what happens immediately after the myosin head binds to the active site on actin?
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the myosin head pivots, moving the actin strand
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after a power stroke, the myosin head must detach from actin before another power stroke can occur. what causes cross bride detachment?
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ATP binds to the mysoin head
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how does the mysoin head obtain the energy required for activation?
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the energy comes from the hydrolysis of ATP
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when does cross bridge cycling end?
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when sufficient calcium has been actively transported back into the sacroplasmic reticulum to allow calcium to unbind from troponin
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when calcium ion binds to troponin
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tropomyosin moves into the groove between the helical action strands
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correct sequence of muscle contraction
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3. Calcium ion is released from the sarcoplasmic reticulum. 5. Calcium ion binds to troponin. 1. Myosin heads bind to the actin. 4. The myosin head pivots toward the center of the sarcomere.6. The myosin head binds an ATP molecule and detaches from the actin. 2. The free myosin head splits ATP.
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in rigor mortis:
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the myosin heads are attached to actin, cross-bridge cycling is absent, and ATP is depleted
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a resting muscle generates most of its ATP by
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the aeorbic metabolism of fatty acids
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creatine phosphate
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actins as an energy reserve in muscle tissue
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if a tissue has intercalated disks, is involunary, and typically has only one nucleus per cell, then that tissue would be
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cardiac muscle
