Muscle Structure Flashcards
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Questions and Answers

What is the definition of epimysium?

  • Connective tissue surrounding a muscle (correct)
  • A type of tendon
  • A type of muscle fiber
  • Connective tissue surrounding muscle fibers

    • What is the definition of tendon?

  • A type of cartilage
  • A type of muscle fiber
  • Connective tissue surrounding a muscle
  • Connective tissue that connects muscle to bone (correct)

    • What is the definition of aponeurosis?

  • Connective tissue that connects muscle to bone
  • Connective tissue surrounding a muscle
  • A type of muscle fiber
  • A broad, flat tendon (correct)

    • What is the definition of perimysium?

    <p>Connective tissue surrounding muscle fibers</p> Signup and view all the answers

    What is the definition of endomysium?

    <p>Connective tissue surrounding muscle fibers</p> Signup and view all the answers

    What is the definition of sarcolemma?

    <p>The plasma membrane of a muscle cell</p> Signup and view all the answers

    What is the definition of endoplasmic reticulum?

    <p>An organelle involved in protein synthesis</p> Signup and view all the answers

    What are synaptic vesicles?

    <p>Small organelles that store neurotransmitters</p> Signup and view all the answers

    What is the definition of synaptic cleft?

    <p>Space between two cells at a synapse</p> Signup and view all the answers

    What is the definition of motor end plate?

    <p>Specialized synapse between motor neuron and muscle fiber</p> Signup and view all the answers

    What are junctional folds of the motor end plate?

    <p>Folds in the muscle fiber membrane</p> Signup and view all the answers

    What is a neurotransmitter?

    <p>Chemical messenger used in synapse communication</p> Signup and view all the answers

    What is acetylcholine?

    <p>A neurotransmitter involved in muscle contraction</p> Signup and view all the answers

    What does acetylcholinesterase do?

    <p>Degrades acetylcholine in the synaptic cleft</p> Signup and view all the answers

    What are receptor-operated channels?

    <p>Channels activated by neurotransmitter binding</p> Signup and view all the answers

    What are voltage-operated channels?

    <p>Channels activated by changes in membrane potential</p> Signup and view all the answers

    What is a muscle fiber?

    <p>Basic unit of muscle tissue</p> Signup and view all the answers

    What are myofibrils?

    <p>Contractile elements within muscle fibers</p> Signup and view all the answers

    What are myofilaments?

    <p>Filaments that make up myofibrils</p> Signup and view all the answers

    What are thin filaments?

    <p>Actin-based filaments in muscle contraction</p> Signup and view all the answers

    What is actin?

    <p>Protein that forms the thin filaments</p> Signup and view all the answers

    What is G actin?

    <p>Globular actin monomers</p> Signup and view all the answers

    What is F actin?

    <p>Filamentous actin polymers</p> Signup and view all the answers

    What is tropomyosin?

    <p>Protein that regulates contraction in muscle</p> Signup and view all the answers

    What are troponins TnC, TnT, TnI?

    <p>Proteins involved in muscle contraction regulation</p> Signup and view all the answers

    What are thick filaments?

    <p>Myosin-based filaments in muscle contraction</p> Signup and view all the answers

    What is myosin?

    <p>Protein that forms the thick filaments</p> Signup and view all the answers

    What is myosin tail?

    <p>Part of the myosin molecule that interacts with other proteins</p> Signup and view all the answers

    What is myosin head?

    <p>Part of the myosin molecule that binds to actin</p> Signup and view all the answers

    What are foot proteins?

    <p>Proteins involved in muscle contraction</p> Signup and view all the answers

    What are calcium channels?

    <p>Channels that allow Ca2+ ions to enter the muscle cell</p> Signup and view all the answers

    What is Ca-ATPase?

    <p>Enzyme that pumps Ca2+ ions back into the sarcoplasmic reticulum</p> Signup and view all the answers

    What are T tubules?

    <p>Invaginations of the sarcolemma that transmit action potentials</p> Signup and view all the answers

    What are terminal cisternae?

    <p>Enlargements of the sarcoplasmic reticulum that store Ca2+ ions</p> Signup and view all the answers

    What are triads?

    <p>Structures formed by T tubules and terminal cisternae</p> Signup and view all the answers

    What is the A band?

    <p>Dark band of myosin and actin overlap</p> Signup and view all the answers

    What is I band?

    <p>Light band of only actin</p> Signup and view all the answers

    What is H zone?

    <p>Zone in the A band where there is no overlap</p> Signup and view all the answers

    What is M line?

    <p>Line in the center of the sarcomere</p> Signup and view all the answers

    What is Z line?

    <p>Boundary between sarcomeres</p> Signup and view all the answers

    What is fascicle?

    <p>Bundle of muscle fibers</p> Signup and view all the answers

    What is a sarcomere?

    <p>Functional unit of muscle contraction</p> Signup and view all the answers

    Study Notes

    Connective Tissue Structures

    • Epimysium: Dense connective tissue layer surrounding an entire muscle, providing structural support and protection.
    • Perimysium: Connective tissue that groups muscle fibers into bundles called fascicles, containing blood vessels and nerves.
    • Endomysium: Thin connective tissue layer encasing individual muscle fibers, allowing for interaction between muscle cells and nerves.

    Muscle Structures

    • Tendon: Connective tissue that attaches muscle to bone, transmitting the force generated by muscles during contraction.
    • Aponeurosis: Flat sheet of connective tissue that connects muscles to muscles or to other structures, serving a similar role as tendons.
    • Muscle Fiber: Basic unit of muscle tissue, long multinucleated cells capable of contraction and force generation.

    Cellular Components

    • Sarcolemma: Plasma membrane surrounding each muscle fiber, playing a crucial role in muscle contraction by conducting electrical impulses.
    • Myofibrils: Rod-like structures within muscle fibers, composed of repeating units called sarcomeres, responsible for muscle contraction.
    • Myofilaments: The contractile proteins within myofibrils, divided into thick (myosin) and thin (actin) filaments.

    Filament Proteins

    • Thin Filaments: Composed primarily of actin, along with regulatory proteins such as tropomyosin and troponin, essential for muscle contraction regulation.

      • Actin: Globular protein that polymerizes to form thin filaments.
      • G Actin: Monomeric form of actin, the building block of filamentous actin.
      • F Actin: Filamentous form of actin, formed from G actin subunits.
      • Tropomyosin: Overlapping protein that covers binding sites on actin in relaxed muscles.
      • Troponin (TnC, TnT, TnI): Complex of three proteins that regulate muscle contraction by binding calcium ions and moving tropomyosin.

    • Thick Filaments: Composed mainly of myosin molecules, responsible for generating muscle tension.

      • Myosin: Motor protein with a tail and head structure, functioning as a crossbridge during muscle contraction.
      • Myosin Tail: The elongated tail part of myosin that anchors it within the thick filament.
      • Myosin Head: The globular part of myosin that binds to actin to form crossbridges during contraction.

    Neuromuscular Junction Components

    • Synaptic Vesicles: Membrane-bound structures within nerve endings that store neurotransmitters, including acetylcholine.
    • Synaptic Cleft: The small gap between the presynaptic terminal and the postsynaptic membrane, across which neurotransmitters diffuse.
    • Motor End Plate: Specialized region of the muscle fiber plasma membrane that contains receptors for neurotransmitters.

    Channels and Proteins

    • Voltage Operated Channels: Ion channels that open or close in response to changes in membrane potential, critical for action potential propagation.
    • Receptor Operated Channels: Ion channels that open in response to the binding of neurotransmitters, allowing ions to flow in or out.
    • Calcium Channels: Specialized channels that allow calcium ions to enter the muscle cells, initiating contraction.
    • Ca-ATPase: Enzyme that pumps calcium ions back into the sarcoplasmic reticulum post-contraction, essential for muscle relaxation.

    Muscle Fiber Organization

    • T Tubules: Extensions of the sarcolemma that penetrate into the muscle fiber, facilitating the rapid transmission of action potentials.
    • Terminal Cisternae: Enlarged areas of the sarcoplasmic reticulum adjacent to T tubules, stores calcium ions for muscle contraction.
    • Triads: Structural units consisting of a T tubule flanked by two terminal cisternae, important for the regulation of calcium release during muscle contraction.

    Sarcomere Structure

    • A Band: Dark band in the sarcomere consisting of thick filaments (myosin) and overlapping thin filaments.
    • I Band: Light band in the sarcomere containing only thin filaments (actin).
    • H Zone: Central region of the A band where thick filaments do not overlap with thin filaments during relaxation.
    • M Line: Midpoint of the sarcomere, anchoring thick filaments together.
    • Z Line: Boundary between adjacent sarcomeres, anchoring thin filaments and providing structure to the muscle fiber.

    Miscellaneous

    • Fascicle: A bundle of muscle fibers grouped together, surrounded by perimysium.
    • Sarcomere: Functional unit of a muscle fiber, defined as the segment between two Z lines, responsible for muscle contraction mechanics.

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    Test your knowledge on various muscle structures with this engaging flashcard quiz. Identify terms like epimysium, tendon, and sarcolemma to solidify your understanding of muscular anatomy. Perfect for students of biology or health sciences!

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