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Anatomy & Physiology Key Concepts Exam 3

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  • What type of potentials can excitable cells like muscle fibers and motor neurons generate?

    Action potentials are rapid changes in membrane potential that excitable cells generate to transmit signals.

  • What protein predominantly composes the thick filaments in myofibrils?

    Myosin is the main protein composing thick filaments in muscle cells.

  • What is the most active form of Vitamin D?

    Calcitriol is the hormonally active form of Vitamin D responsible for calcium absorption.

  • Which region of a neuron conducts signals over long distances?

    The axon is the long projection that carries electrical signals away from the neuron cell body.

  • What are clusters of neuron cell bodies called in the peripheral nervous system?

    Ganglia are clusters of neuron cell bodies in the peripheral nervous system.

  • Which protein does Ca2+ bind to in muscle contraction to move tropomyosin away from actin binding sites?

    Troponin binds calcium, causing conformational changes that expose actin binding sites.

  • Which glial cells act as immune cells in the central nervous system?

    Microglia serve as the main immune defense cells in the CNS.

  • What connective tissue surrounds muscle fascicles in skeletal muscle?

    The perimysium is the collagen-rich connective tissue sheath surrounding fascicles.

  • Which neurons perform the integrative functions of the nervous system?

    Interneurons connect sensory and motor neurons and perform integration.

  • What type of suture has interlocking wavy margins in the skull?

    A serrate suture features interlocking wavy margins between articulating bones.

  • What is a joint called that allows only slight movement?

    An amphiarthrosis is a joint permitting slight movement.

  • What term describes the sequence linking a motor neuron action potential to muscle contraction?

    Excitation-contraction coupling is the process from nerve signal to calcium release and muscle contraction.

  • What type of movement does a ball-and-socket joint allow?

    Ball-and-socket joints allow multiaxial movement in multiple planes and axes.

  • What lubricates synovial joints?

    Synovial fluid lubricates synovial joints, reducing friction during movement.

  • How does muscle contraction speed compare between muscles with parallel fascicles and pennate fascicles?

    Muscles with parallel fascicles contract faster but generate less force than pennate muscles.

  • What causes the striated appearance of skeletal and cardiac muscle?

    Striations arise from the regular overlapping pattern of actin (thin) and myosin (thick) filaments.

  • What are key structural features of cardiac muscle cells?

    Cardiac muscle cells are branched, striated, and connected by intercalated discs.

  • What hormone is released when blood calcium is low and what does it stimulate?

    Parathyroid hormone (PTH) is released, stimulating osteoclasts to break down bone and increasing calcium reabsorption and absorption.

  • Name the three main functional classifications of joints by mobility.

    Synarthrosis: immovable, amphiarthrosis: slightly movable, diarthrosis: freely movable joints.

  • What are the basic properties of muscle tissue?

    Muscle tissue properties include excitability, contractility, extensibility, and elasticity.

  • What is the functional unit of skeletal muscle contraction?

    The sarcomere is the contractile unit composed of thick (myosin) and thin (actin) filaments.

  • Describe the crossbridge cycle in muscle contraction.

    Myosin heads bind actin, perform a power stroke pulling actin, detach with ATP binding, and re-cock after ATP hydrolysis.

  • What neurotransmitter is released at the neuromuscular junction to activate muscle fibers?

    Acetylcholine (ACh) is released, binding nicotinic receptors to depolarize muscle fibers.

  • What is a motor unit?

    A motor unit consists of one motor neuron and all the muscle fibers it innervates.

  • What are the three ATP regeneration pathways in muscle fibers?

    Direct phosphorylation, anaerobic glycolysis, and aerobic respiration regenerate ATP depending on activity intensity.

  • What are the three types of muscle fibers based on metabolism and fatigue resistance?

    Slow oxidative (fatigue-resistant), fast glycolytic (fatigue quickly), and fast oxidative (intermediate properties).

  • Name the three classes of levers in the musculoskeletal system.

    First-class: fulcrum between effort and load; second-class: load between fulcrum and effort; third-class: effort between fulcrum and load.

  • What cells form myelin in the CNS and PNS respectively?

    Oligodendrocytes form myelin in the CNS; Schwann cells form myelin in the PNS.

  • What maintains the resting membrane potential in neurons?

    The Na+/K+ ATPase pump and leakage channels maintain resting membrane potential by moving 3 Na+ out and 2 K+ in.

  • What are the phases of an action potential?

    Depolarization (Na+ influx), repolarization (K+ efflux), and hyperpolarization (K+ channels remain open briefly).