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Anatomy & Physiology: Muscle and Nervous System Fundamentals

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Terms in this set (27)

  • Three types of muscle tissue

    Skeletal (striated, voluntary), Cardiac (striated, involuntary), and Smooth (non-striated, involuntary).

  • Four main characteristics of muscle tissue

    Excitability, Contractility, Extensibility, and Elasticity.

  • Functions of muscles

    Produce movement, maintain posture, stabilize joints, and generate heat.

  • Connective tissue sheaths of skeletal muscle

    Epimysium surrounds entire muscle, Perimysium surrounds fascicles, Endomysium surrounds individual muscle fibers.

  • Difference between direct and indirect muscle attachments

    Direct: epimysium fused to bone periosteum; Indirect: connective tissue extends as tendon or aponeurosis.

  • Sarcomere

    Smallest contractile unit of muscle fiber, extends from one Z disc to the next.

  • Myofilaments in sarcomere

    Thick filaments made of myosin; Thin filaments made of actin, tropomyosin, and troponin.

  • Role of titin in muscle fibers

    Elastic filament that holds thick filaments in place and helps recoil after stretch.

  • Sarcoplasmic reticulum function

    Stores and releases Ca2+ to regulate intracellular calcium levels for muscle contraction.

  • T tubules function

    Transmit action potentials deep into muscle fiber to trigger Ca2+ release from sarcoplasmic reticulum.

  • Sliding filament model of contraction

    Thin filaments slide past thick filaments, increasing overlap and shortening sarcomere without changing filament length.

  • Four steps of cross bridge cycle

    1. Cross bridge formation, 2. Power stroke, 3. Cross bridge detachment, 4. Cocking of myosin head.

  • Events at neuromuscular junction

    Motor neuron releases ACh, which binds sarcolemma receptors, triggering action potential and muscle contraction.

  • Generation of action potential on sarcolemma

    1. End plate potential (ACh opens Na+ channels), 2. Depolarization (voltage-gated Na+ channels open), 3. Repolarization (K+ channels open).

  • Excitation-contraction coupling

    AP propagates along sarcolemma and T tubules, triggering Ca2+ release from SR, leading to contraction.

  • Motor unit

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

  • Muscle twitch phases

    Latent period (E-C coupling), contraction phase (cross bridge formation), relaxation phase (Ca2+ reuptake).

  • Wave (temporal) summation

    Multiple stimuli in rapid succession cause increased muscle tension due to incomplete relaxation.

  • Difference between isotonic and isometric contractions

    Isotonic: muscle changes length and moves load; Isometric: muscle tension increases but length stays the same.

  • Three mechanisms to regenerate ATP in muscle

    Direct phosphorylation by creatine phosphate, anaerobic glycolysis, and aerobic respiration.

  • Anaerobic glycolysis

    Glucose broken down to pyruvic acid without oxygen, producing 2 ATP and lactic acid.

  • Aerobic respiration

    Uses oxygen to break down glucose into CO2, H2O, and produces ~32 ATP.

  • Muscle fatigue causes

    Ionic imbalances (K+, Ca2+, Pi) interfering with excitation-contraction coupling; lack of ATP is rare cause.

  • Excess postexercise oxygen consumption (EPOC)

    Extra oxygen needed after exercise to restore oxygen reserves, convert lactic acid, and replenish ATP and creatine phosphate.

  • Role of acetylcholinesterase at neuromuscular junction

    Breaks down ACh to stop muscle contraction and allow relaxation.

  • Effect of curare toxin on muscle

    Blocks ACh receptors, preventing muscle stimulation and causing paralysis.

  • Rigor mortis cause

    ATP depletion after death prevents cross bridge detachment, causing sustained muscle contraction.