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Muscular System - Anatomy & Physiology

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  • What are the three types of muscle tissue?

    Skeletal, cardiac, and smooth muscle tissues.

  • What is the primary function of skeletal muscle?

    To produce voluntary movement by contracting and pulling on bones.

  • Where is cardiac muscle found and what is its function?

    Found only in the heart; it contracts to pump blood throughout the body.

  • Describe smooth muscle and where it is located.

    Involuntary, non-striated muscle found in walls of hollow organs like intestines and blood vessels.

  • What is a muscle fiber?

    A single muscle cell, long and cylindrical, containing multiple nuclei.

  • What is the role of myofibrils in muscle fibers?

    Myofibrils are contractile elements composed of sarcomeres that enable muscle contraction.

  • Define a sarcomere.

    The basic contractile unit of muscle fiber, made of actin and myosin filaments.

  • What proteins make up the thin and thick filaments in a sarcomere?

    Thin filaments are primarily actin; thick filaments are primarily myosin.

  • How does muscle contraction occur at the molecular level?

    Myosin heads bind to actin and pull filaments past each other using ATP, shortening the sarcomere.

  • What is the role of calcium ions in muscle contraction?

    Calcium binds to troponin, causing tropomyosin to move and expose binding sites on actin for myosin.

  • What is the neuromuscular junction?

    The synapse where a motor neuron communicates with a muscle fiber to trigger contraction.

  • What neurotransmitter is released at the neuromuscular junction?

    Acetylcholine (ACh) is released to stimulate muscle contraction.

  • Define muscle origin and insertion.

    Origin is the fixed attachment point; insertion is the movable attachment point of a muscle.

  • What is the difference between isotonic and isometric muscle contractions?

    Isotonic changes muscle length to move a load; isometric generates force without changing length.

  • What is muscle hypertrophy?

    An increase in muscle size due to growth of individual muscle fibers.

  • Name the connective tissue layers surrounding muscle from smallest to largest.

    Endomysium surrounds fibers, perimysium surrounds fascicles, epimysium surrounds the entire muscle.

  • What is the role of ATP in muscle contraction?

    ATP provides energy for myosin head movement and detachment from actin during contraction cycles.

  • What causes muscle fatigue?

    Depletion of ATP, accumulation of lactic acid, and ionic imbalances impair contraction.

  • What is the sliding filament theory?

    Muscle contraction occurs as actin filaments slide over myosin filaments, shortening sarcomeres.

  • How do motor units affect muscle control?

    A motor unit is one motor neuron and all the muscle fibers it innervates; smaller units allow finer control.