Muscular system
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Questions and Answers

Which type of muscle tissue is found in the heart wall?

  • Smooth muscle
  • Skeletal muscle
  • Cardiac muscle (correct)
  • Connective tissue

    • What type of muscle tissue is responsible for pushing things through organs?

  • Skeletal muscle
  • Cardiac muscle
  • Adipose tissue
  • Smooth muscle (correct)

    • Which type of muscle tissue is voluntary and attached to bones for movement?

  • Smooth muscle
  • Cardiac muscle
  • Skeletal muscle (correct)
  • Nervous tissue

    • What is the size of skeletal muscle fibers?

    <p>Huge</p> Signup and view all the answers

    What are the striations in skeletal muscle fibers made of?

    <p>Thin and thick filaments</p> Signup and view all the answers

    Why are skeletal muscle fibers multinucleate?

    <p>To control structural protein production</p> Signup and view all the answers

    How do myoblasts become multinucleate in skeletal muscle development?

    <p>They fuse together</p> Signup and view all the answers

    What is the role of myosatellite cells in muscle injury?

    <p>Enlarging, dividing, and fusing with damaged muscle fibers</p> Signup and view all the answers

    What is the function of myosatellite cells that did not fuse in development?

    <p>Enlarging, dividing, and fusing with damaged muscle fibers</p> Signup and view all the answers

    What is the function of perimysium in skeletal muscle organization?

    <p>Divides skeletal muscle into compartments (fascicles)</p> Signup and view all the answers

    Where do the collagen fibers of epimysium, perimysium, and endomysium converge at the end of a muscle?

    <p>To form tendons and aponeuroses</p> Signup and view all the answers

    What is the role of endomysium in skeletal muscle organization?

    <p>Surrounds individual muscle fibers</p> Signup and view all the answers

    Where do arterioles supply blood in the skeletal muscle organization?

    <p>To capillary network in endomysium</p> Signup and view all the answers

    What is the pathway of nerve fibers in skeletal muscle organization?

    <p>Penetrate epimysium, branch through perimysium, enter endomysium</p> Signup and view all the answers

    Where do blood vessels and nerves enter in skeletal muscle organization?

    <p>Together, branch through perimysium</p> Signup and view all the answers

    What is the function of titin in muscle tissue?

    <p>Acts as an elastic component associated with myosin</p> Signup and view all the answers

    Where are mitochondria located in muscle tissue?

    <p>Scattered among myofibrils</p> Signup and view all the answers

    What happens when myofibrils contract in muscle tissue?

    <p>The entire cell shortens and pulls on the tendon</p> Signup and view all the answers

    What is the function of T tubules in muscle cells?

    <p>Conducting electrical impulses for muscle contraction</p> Signup and view all the answers

    What is the structure formed by the combination of 2 terminal cisternae and 1 T tubule?

    <p>Triad</p> Signup and view all the answers

    What is the role of the sarcoplasmic reticulum (SR) in muscle cells?

    <p>Stores, releases, and retrieves Ca2+ ions</p> Signup and view all the answers

    What structural feature of sarcomeres is directly responsible for muscle contractions?

    <p>Interactions between thick and thin filaments</p> Signup and view all the answers

    What is the primary component of the A band in a sarcomere?

    <p>Overlapping thick and thin filaments</p> Signup and view all the answers

    Where is the H Band located within the sarcomere?

    <p>On either side of the M line</p> Signup and view all the answers

    What is the role of the Z line in the structure of a sarcomere?

    <p>It marks the boundary between adjacent sarcomeres</p> Signup and view all the answers

    Which region of the sarcomere contains only thin filaments and extends from one A band to the next?

    <p>I Band</p> Signup and view all the answers

    What is the significance of the M Line in the sarcomere?

    <p>It connects thick filaments and stabilizes their position</p> Signup and view all the answers

    Which feature contributes to the striated appearance of muscle cells?

    <p>The alignment of Z lines across myofibrils</p> Signup and view all the answers

    What happens to the I Band during muscle contraction?

    <p>It shortens as the sarcomere contracts</p> Signup and view all the answers

    What protein covers the active sites on G-actin, preventing actin-myosin interaction at rest?

    <p>Tropomyosin</p> Signup and view all the answers

    What protein binds to one G-actin, holding the troponin-tropomyosin complex in position?

    <p>Troponin</p> Signup and view all the answers

    What protein has a receptor that binds 2 calcium ions to initiate a contraction?

    <p>Troponin</p> Signup and view all the answers

    Which protein forms a long strand holding F-actin together and extends along the F-actin strand between G-actin molecules?

    <p>Nebulin</p> Signup and view all the answers

    What molecule has active sites where myosin (in thick filament) can bind for contractions?

    <p>G-actin</p> Signup and view all the answers

    What is the primary function of titin in muscle tissue?

    <p>Anchoring thick filaments to the M line and maintaining proper alignment with thin filaments</p> Signup and view all the answers

    What happens to the titin strands during muscle contraction?

    <p>They recoil after stretching</p> Signup and view all the answers

    During muscle contraction, what is the primary role of the myosin heads?

    <p>Interact with actin filaments, forming cross-bridges and producing motion</p> Signup and view all the answers

    What is the function of the core of titin within the thick filament?

    <p>Keeps thick and thin filaments in proper alignment</p> Signup and view all the answers

    What is the function of titin in muscle tissue?

    <p>Acts as an elastic protein that recoils after stretching</p> Signup and view all the answers

    Where does titin extend within the sarcomere in muscle tissue?

    <p>From the M line to the Z line within the I band</p> Signup and view all the answers

    What happens to the myosin heads during muscle contraction?

    <p>They interact with actin filaments, forming cross-bridges and pivot to produce motion</p> Signup and view all the answers

    What is the primary function of the core of titin within the thick filament?

    <p>Keeps thick and thin filaments in proper alignment</p> Signup and view all the answers

    What remains unchanged in width during muscle contraction according to the Sliding Filament Theory?

    <p>A band</p> Signup and view all the answers

    What prevents myosin from binding to actin in a relaxed muscle?

    <p>Tropomyosin</p> Signup and view all the answers

    During muscle contraction, the shortening of which structure leads to the muscle fiber shortening?

    <p>Myofibril</p> Signup and view all the answers

    Which bands narrow as the thin filaments slide toward the center of the sarcomere during muscle contraction?

    <p>I bands and H bands</p> Signup and view all the answers

    What is held in place by troponin in a relaxed muscle?

    <p>Tropomyosin strands</p> Signup and view all the answers

    During a muscle contraction, which band remains constant in width according to the Sliding Filament Theory?

    <p>A bands</p> Signup and view all the answers

    What happens to the I bands during muscle contraction?

    <p>They disappear</p> Signup and view all the answers

    What changes occur to the H bands and I bands during muscle contraction?

    <p>H bands and I bands narrow</p> Signup and view all the answers

    What happens to the Z lines during muscle contraction?

    <p>They move closer together</p> Signup and view all the answers

    What occurs to the zones of overlap between thin and thick filaments during muscle contraction?

    <p>They widen</p> Signup and view all the answers

    What is the primary function of the sodium-potassium pump in the maintenance of resting membrane potential?

    <p>Bringing membrane potential back to 'rest'</p> Signup and view all the answers

    What accounts for approximately 93% of ion movement across the cell membrane under resting conditions?

    <p>Passive forces</p> Signup and view all the answers

    What type of potentials are responsible for long-distance signals in excitable membranes?

    <p>Action potentials</p> Signup and view all the answers

    What happens if the continuous leakage of Na+ and K+ across the membrane is allowed?

    <p>Resting membrane potential may vanish</p> Signup and view all the answers

    What is the significance of an excitable cell?

    <p>It can produce action potentials</p> Signup and view all the answers

    Which type of cells generally use only small changes in membrane potential to initiate their responses?

    <p>Epithelial cells</p> Signup and view all the answers

    What is the term for the period where no other action potential can be generated in the cell?

    <p>Absolute refractory period</p> Signup and view all the answers

    Which type of muscle tissue generally uses propagating action potentials to initiate their responses?

    <p>Smooth muscle cells</p> Signup and view all the answers

    What is the term for the period where another action potential can be generated, but a large stimulus is needed?

    <p>Relative refractory period</p> Signup and view all the answers

    Which cells are characterized by having a high number of voltage-gated ion channels?

    <p>Skeletal muscle cells</p> Signup and view all the answers

    What is the term for the period where no other action potential can be generated in a cell?

    <p>Absolute refractory period</p> Signup and view all the answers

    Which type of cells generally use only small changes in membrane potential to initiate their responses?

    <p>Epithelial cells</p> Signup and view all the answers

    What type of cells are characterized by having a high number of voltage-gated ion channels and using propagating action potentials to initiate their responses?

    <p>Heart cells</p> Signup and view all the answers

    What is the term for the membrane potential moving from a positive value to -70mV?

    <p>Repolarization</p> Signup and view all the answers

    Which type of cells have few voltage-gated ion channels and generally use only small changes in membrane potential to initiate their responses?

    <p>Liver cells</p> Signup and view all the answers

    What is the primary function of the Sodium-Potassium pump in the context of the Resting Membrane Potential?

    <p>Preventing the continuous leakage of Na+ &amp; K+ to maintain RMP</p> Signup and view all the answers

    What accounts for approximately 93% of ion movement across the cell membrane under resting conditions?

    <p>Passive forces</p> Signup and view all the answers

    What is the primary role of transient changes in resting membrane potential in excitable cells?

    <p>Producing electrical signals for short-distance cell communication</p> Signup and view all the answers

    What is the primary function of the all-or-none law in the context of action potentials?

    <p>Determining whether an action potential will occur</p> Signup and view all the answers

    What is the significance of the unequal charge distribution in excitable cells?

    <p>It polarizes the cell</p> Signup and view all the answers

    What is the term for the period when the cell rapidly repolarizes and K+ gates open?

    <p>Depolarization</p> Signup and view all the answers

    What causes hyperpolarization of the membrane during the action potential process?

    <p>Excessive efflux of K+</p> Signup and view all the answers

    What occurs once the peak of action potential is reached?

    <p>Voltage-gated Na+ channels close</p> Signup and view all the answers

    What happens to the membrane potential during depolarization?

    <p>Inside of the cell reverses from a negative to a positive charge</p> Signup and view all the answers

    What occurs when the membrane potential moves from a negative value to a positive peak of +30mV?

    <p>Depolarization</p> Signup and view all the answers

    What happens after the peak of the action potential when the cell rapidly repolarizes?

    <p>Na+ gates close and K+ gates open</p> Signup and view all the answers

    What causes the hyperpolarization of the membrane in the neuron?

    <p>Excessive efflux of K+ due to open potassium gates</p> Signup and view all the answers

    What prevents further depolarization once the hyperpolarization occurs?

    <p>Excessive efflux of K+ due to open potassium gates</p> Signup and view all the answers

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