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Anatomy & Physiology: Muscle Tissue and Contraction

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Terms in this set (20)

  • What are the three main types of muscle tissue?

    Skeletal, cardiac, and smooth muscle tissues.

  • Name four main characteristics of muscle tissue.

    Excitability, contractility, extensibility, and elasticity.

  • List four main functions of muscle tissue.

    Movement, posture maintenance, joint stabilization, and heat generation.

  • What connective tissue sheaths surround muscle from smallest to largest scale?

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

  • Describe the sliding filament model of muscle contraction.

    Actin filaments slide past myosin filaments, shortening the sarcomere and causing muscle contraction.

  • What is the role of the neuromuscular junction in muscle contraction?

    It is the synapse where a motor neuron releases neurotransmitters to stimulate a muscle fiber to contract.

  • What ions are primarily involved in the Na+/K+ pump function?

    Sodium (Na+) and potassium (K+) ions are exchanged to maintain resting membrane potential.

  • What are the four steps of skeletal muscle contraction?

    1. Excitation, 2. Excitation-contraction coupling, 3. Contraction, 4. Relaxation.

  • What happens during the cross bridge cycle in muscle contraction?

    Myosin heads attach to actin, pivot to pull filaments, detach using ATP, and reset to repeat the cycle.

  • Why is ATP essential for muscle contraction?

    ATP provides energy for myosin head detachment from actin and powers the Na+/K+ pump to restore ion gradients.

  • What triggers the release of calcium ions in muscle contraction?

    Action potentials traveling along the sarcolemma trigger calcium release from the sarcoplasmic reticulum.

  • How does calcium enable muscle contraction at the molecular level?

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

  • What is the function of the sarcoplasmic reticulum in muscle cells?

    It stores and releases calcium ions to regulate muscle contraction.

  • Define a sarcomere.

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

  • What is the role of tropomyosin in muscle contraction?

    Tropomyosin blocks myosin-binding sites on actin when the muscle is relaxed.

  • What causes the muscle to relax after contraction?

    Calcium ions are pumped back into the sarcoplasmic reticulum, tropomyosin covers binding sites, and cross bridges detach.

  • How does the Na+/K+ pump contribute to muscle excitability?

    It maintains the resting membrane potential by moving 3 Na+ out and 2 K+ into the cell using ATP.

  • What is the significance of the motor end plate at the neuromuscular junction?

    It contains receptors for acetylcholine that initiate muscle fiber depolarization.

  • What molecule is released by motor neurons to stimulate muscle contraction?

    Acetylcholine (ACh) is released into the synaptic cleft at the neuromuscular junction.

  • Explain the role of ATP in the cross bridge cycle.

    ATP binds to myosin, allowing it to detach from actin and re-cock for another contraction cycle.