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Muscle Anatomy & Physiology High-Yield Flashcards

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  • 3 types of muscle tissue

    Skeletal, cardiac, and smooth muscle.

  • Muscular system includes only ______ muscles

    Skeletal muscles.

  • Main functions of skeletal muscle

    Movement, posture, support, temperature regulation, and guarding openings.

  • Epimysium

    Connective tissue that surrounds the entire muscle.

  • Perimysium

    Connective tissue that surrounds fascicles (bundles of muscle fibers).

  • Endomysium

    Connective tissue that surrounds individual muscle fibers.

  • Fascicle

    A bundle of muscle fibers.

  • Muscle fiber

    A muscle cell.

  • Sarcolemma

    The cell membrane of a muscle fiber.

  • Sarcoplasm

    The cytoplasm of a muscle fiber.

  • Myofibrils are made of?

    Myofilaments (thin and thick filaments).

  • Thin filaments

    Actin filaments.

  • Thick filaments

    Myosin filaments.

  • Functional unit of muscle

    Sarcomere.

  • Sarcomere boundaries

    Z lines define the boundaries of a sarcomere.

  • A band

    Region containing thick filaments (myosin).

  • I band

    Region containing thin filaments (actin) only.

  • H zone

    Region with thick filaments only, no overlap.

  • What happens during muscle contraction?

    Thin filaments slide over thick filaments, shortening the sarcomere.

  • Does the A band change length during contraction?

    No, the A band remains the same length.

  • What shortens during contraction?

    The I band and H zone shorten.

  • Source of Ca²⁺ for muscle contraction

    Sarcoplasmic reticulum releases Ca²⁺.

  • Ca²⁺ binds to which protein to trigger contraction?

    Troponin.

  • What blocks the myosin binding sites on actin at rest?

    Tropomyosin blocks binding sites.

  • Function of ATP in muscle contraction

    Powers contraction by enabling myosin head movement and detachment.

  • What happens without ATP in muscle?

    Muscle stays contracted, causing rigor mortis.

  • Myosin binds to which filament during contraction?

    Actin (thin filament).

  • Power stroke in muscle contraction

    Myosin pulls actin toward the center of the sarcomere.

  • Role of ATP after power stroke

    ATP causes myosin detachment from actin.

  • Neurotransmitter at neuromuscular junction

    Acetylcholine (ACh).

  • Effect of ACh at neuromuscular junction

    Na⁺ enters muscle fiber, triggering an action potential.

  • Enzyme that breaks down ACh

    Acetylcholinesterase.

  • When does muscle relaxation occur?

    When Ca²⁺ levels decrease in the sarcoplasm.

  • Creatine phosphate role

    Provides a quick source of ATP during muscle contraction.

  • Primary source of ATP for sustained muscle activity

    Aerobic respiration.

  • Anaerobic glycolysis produces?

    Fast ATP and lactic acid.

  • Cause of muscle fatigue

    Low ATP and lactic acid buildup.

  • Features of slow (Type I) muscle fibers

    Red, slow contraction, and high endurance.

  • Features of fast (Type II) muscle fibers

    White, fast contraction, and fatigue quickly.

  • Location of cardiac muscle

    Found in the heart.

  • Key feature of cardiac muscle

    Intercalated discs that connect cells.

  • Function of cardiac muscle

    Contracts as one unit to pump blood.

  • Is smooth muscle striated?

    No, smooth muscle is non-striated.

  • Location of smooth muscle

    Found in organs like intestines and blood vessels.

  • Control of smooth muscle

    Involuntary control.