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Muscle Tissue and Physiology - Anatomy & Physiology

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Terms in this set (30)

  • Three types of muscle tissue

    Skeletal, cardiac, and smooth muscle.

  • Common function of all muscle tissue types

    Contraction to produce movement.

  • Characteristic of skeletal muscle cells

    Long, multinucleated fibers with voluntary contractions controlled by conscious thought.

  • Characteristic of cardiac muscle cells

    Short, branched cells with 1-2 nuclei and intercalated discs; contractions are involuntary.

  • Unique features of smooth muscle cells

    Spindle-shaped, single nucleus, found in hollow organs; contractions are involuntary and not striated.

  • Define contractility

    The ability of muscle cells to shorten forcefully.

  • Define excitability

    The ability to respond to stimuli by generating electrical signals.

  • Define conductivity

    The ability to propagate electrical signals along the muscle cell membrane.

  • Define distensibility

    The ability to stretch without damage.

  • Define elasticity

    The ability to return to original length after stretching.

  • Sarcoplasm and sarcolemma

    Sarcoplasm is the cytoplasm of a muscle cell; sarcolemma is the plasma membrane.

  • Function of sarcoplasmic reticulum (SR)

    Stores and releases calcium ions to trigger muscle contraction.

  • Composition of thick filaments

    Bundles of myosin proteins with globular heads that bind actin.

  • Proteins composing thin filaments

    Actin (contractile), tropomyosin (regulatory), and troponin (regulatory).

  • Role of tropomyosin and troponin

    Tropomyosin blocks actin's active sites; troponin holds tropomyosin in place and regulates contraction.

  • Elastic filaments are made of

    Titin, a spring-like protein that stabilizes myofibrils and resists overstretching.

  • Sarcomere structure: I band and A band

    I band contains only thin filaments; A band contains thick and thin filaments overlapping.

  • What shortens during muscle contraction?

    I band and H zone narrow; A band remains the same length.

  • Resting membrane potential of muscle fiber

    Approximately -90 mV, due to ion distribution across the sarcolemma.

  • Role of Na+/K+ pump

    Moves 3 Na+ ions out and 2 K+ ions into the cell to maintain concentration gradients.

  • Stages of an action potential

    Depolarization: membrane potential becomes positive; Repolarization: returns to resting negative potential.

  • Neurotransmitter at neuromuscular junction

    Acetylcholine (ACh) is released to stimulate muscle fibers.

  • Excitation-contraction coupling

    Action potential triggers Ca++ release from SR, linking electrical signal to contraction.

  • Crossbridge cycle requires

    ATP binding and hydrolysis to cock myosin heads and enable contraction.

  • Muscle relaxation process

    Acetylcholine stops, Ca++ pumped back into SR, troponin and tropomyosin block actin sites, ending contraction.

  • Immediate energy source for muscle contraction

    Creatine phosphate stores energy to rapidly regenerate ATP for about 10 seconds.

  • Difference between glycolytic and oxidative catabolism

    Glycolysis is anaerobic and fast; oxidative catabolism requires oxygen and produces more ATP for sustained activity.

  • Types of skeletal muscle fibers

    Type I: slow-twitch, oxidative; Type II: fast-twitch, glycolytic or oxidative-glycolytic.

  • Motor unit definition

    A single motor neuron and all the muscle fibers it innervates.

  • Isotonic vs isometric contractions

    Isotonic: muscle changes length; isometric: muscle length stays the same while tension changes.