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Muscle Anatomy & Physiology Study Guide

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  • Functions of muscles

    Movement, posture maintenance, heat production, and stabilizing joints.

  • Properties of muscle tissues and the differences

    Excitability, contractility, extensibility, and elasticity.

  • What are fascicles?

    Bundles of muscle fibers grouped together within a muscle.

  • What is sarcoplasm?

    The cytoplasm of a muscle fiber containing glycogen and myoglobin.

  • Sarcoplasmic reticulum and its role

    A specialized smooth ER that stores and releases calcium ions to trigger muscle contraction.

  • Thin and thick filaments

    Thin filaments are mainly actin; thick filaments are mainly myosin, both essential for contraction.

  • What is a sarcomere?

    The functional contractile unit of a muscle fiber, defined by Z discs.

  • Neuromuscular junction and what happens there

    Site where a motor neuron releases acetylcholine to stimulate muscle fiber contraction.

  • Events during the contraction cycle when calcium is released

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

  • Three types of muscle fibers

    Slow oxidative, fast oxidative, and fast glycolytic fibers differ in speed and fatigue resistance.

  • Synergistic muscle contractions

    Muscles that work together to perform the same movement.

  • Different shapes and arrangements of muscles

    Examples include parallel, fusiform, pennate, and circular muscle arrangements.

  • Difference between muscle types and their roles

    Skeletal: voluntary movement; cardiac: heart pumping; smooth: involuntary control of organs.

  • Connective tissue types in muscles

    Epimysium surrounds the whole muscle, perimysium surrounds fascicles, endomysium surrounds individual fibers.

  • Depolarization and repolarization in action potential

    Depolarization: Na+ influx makes inside positive; repolarization: K+ efflux restores negative resting potential.

  • What happens during partial muscle contraction

    Some motor units are active, producing graded muscle tension rather than full contraction.

  • Sliding filament theory components

    Myosin heads pull actin filaments inward, shortening the sarcomere during contraction.

  • Sarcomere contraction zones affected

    I band and H zone shorten; A band remains constant.

  • Role of calcium in muscle contraction

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

  • How muscle restores energy

    Through creatine phosphate system, anaerobic glycolysis, and aerobic respiration.

  • What is a motor unit and which is more precise

    A motor neuron and all muscle fibers it controls; smaller motor units allow more precise control.

  • Which muscle type regenerates best

    Smooth muscle regenerates better than skeletal or cardiac muscle.

  • Composition of skeletal muscle

    Made of muscle fibers, connective tissue, blood vessels, and nerves.

  • What is an aponeurosis?

    A broad, flat tendon-like sheet connecting muscle to bone or other muscles.

  • Where is calcium stored in muscle?

    In the sarcoplasmic reticulum of muscle fibers.

  • What happens during muscle fatigue and energy restoration

    Fatigue occurs from energy depletion and waste buildup; recovery uses oxygen to restore ATP and clear metabolites.

  • Role of acetylcholine in muscle contraction

    It stimulates muscle fibers by binding receptors at the neuromuscular junction.

  • Role of myoglobin in muscle fibers

    Myoglobin stores and transports oxygen within muscle cells.

  • How muscle contraction works in smooth muscle

    Calcium binds calmodulin, activating myosin light-chain kinase to enable cross-bridge cycling.

  • Role of fulcrum, lever, and load

    Fulcrum is the pivot point; lever is the bone; load is the resistance to movement.

  • criteria to name muscles?

    Location, Name, size