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Anatomy & Physiology: Muscle and Nervous System Fundamentals

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이 집합의 용어 (30)

  • Three types of muscle tissue

    Skeletal (voluntary, striated, attached to bones), Cardiac (involuntary, striated, heart), and Smooth (involuntary, non-striated, walls of organs).

  • Five properties of muscle cells

    Excitability, Conductivity, Contractility, Extensibility, and Elasticity.

  • Function of sarcoplasmic reticulum in muscle fiber

    Stores and releases calcium ions to trigger muscle contraction.

  • Role of T-tubules in muscle fibers

    Transmit action potentials deep into the muscle fiber to stimulate calcium release.

  • Definition of sarcomere

    The basic contractile unit of a muscle fiber, composed of organized thick and thin filaments between two Z discs.

  • Protein components of thick and thin filaments

    Thick filaments contain myosin; thin filaments contain actin, troponin, and tropomyosin.

  • Structure of the sarcomere bands

    I band: thin filaments only; A band: thick filaments (with overlap); H zone: thick filaments only; M line: center of thick filaments; Z disc: boundary of sarcomere.

  • Function of troponin and tropomyosin

    Troponin binds calcium to move tropomyosin off actin's myosin-binding sites, allowing contraction.

  • Myosin head role in muscle contraction

    Myosin heads bind actin, hydrolyze ATP, perform power stroke, detach, and reset for repeated contraction cycles.

  • Events triggered by calcium binding to troponin

    Causes tropomyosin to move, exposing myosin binding sites on actin, enabling crossbridge formation.

  • Changes in sarcomere bands during contraction

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

  • Connective tissue layers in skeletal muscle

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

  • Events at the neuromuscular junction

    Motor neuron releases acetylcholine (ACh) into synaptic cleft, binds receptors on muscle, triggering action potential.

  • Role of acetylcholinesterase

    Enzyme that breaks down ACh in synaptic cleft to stop muscle stimulation.

  • Resting membrane potential and depolarization in muscle

    ACh binding opens channels, causing Na+ influx, depolarizing sarcolemma and generating action potential.

  • Path of action potential in muscle fiber

    Travels along sarcolemma, down T-tubules, triggering calcium release from sarcoplasmic reticulum.

  • Three ATP-generating pathways in muscle cells

    Aerobic respiration (long-term), anaerobic respiration (short-term), and creatine phosphate system (immediate).

  • Role of myoglobin in muscle

    Stores oxygen in muscle cells to support aerobic respiration.

  • Phases of a muscle twitch

    Latent period (delay), contraction period, and relaxation period.

  • Difference between fast-twitch and slow-twitch fibers

    Fast-twitch fibers contract quickly, fatigue fast; slow-twitch fibers contract slowly, resist fatigue.

  • Definition of motor unit

    A motor neuron and all the muscle fibers it innervates; recruitment increases muscle force.

  • Muscle tone definition

    Continuous, passive partial contraction of muscles to maintain posture and readiness.

  • Isometric vs isotonic contractions

    Isometric: muscle length stays same, tension changes; isotonic: muscle length changes, tension constant.

  • Definition of muscle hypertrophy

    Increase in muscle size due to growth of individual muscle fibers from exercise.

  • Causes of muscle fatigue

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

  • Location and characteristics of smooth muscle

    Found in walls of hollow organs; involuntary, non-striated, spindle-shaped cells.

  • Single-unit vs multiunit smooth muscle

    Single-unit cells contract together via gap junctions; multiunit cells contract independently.

  • Sequence of smooth muscle contraction steps

    Calcium binds calmodulin, activates myosin light chain kinase, phosphorylates myosin, crossbridge cycling, contraction.

  • Definition of origin and insertion of a muscle

    Origin: fixed attachment; insertion: movable attachment of a muscle.

  • Difference between agonists, antagonists, synergists, and fixators

    Agonists cause movement; antagonists oppose it; synergists assist; fixators stabilize origin.