Cardiovascular Physiology Quiz
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Cardiovascular Physiology Quiz

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Questions and Answers

What effect does increased preload have on stroke volume (SV)?

  • It decreases SV.
  • It reduces SV only in patients with heart disease.
  • It has no effect on SV.
  • It increases SV. (correct)

    • What is defined as the resistance the heart must overcome to eject blood?

  • Contractility
  • Preload
  • Afterload (correct)
  • Heart rate

    • How does increased afterload affect cardiac output (CO)?

  • It has a negligible effect on CO.
  • It reduces CO. (correct)
  • It increases CO only in well-conditioned hearts.
  • It increases CO regardless of other factors.

    • Which statement correctly describes the relationship between preload and stroke volume according to the Frank-Starling Mechanism?

    <p>Greater preload enhances stroke volume.</p> Signup and view all the answers

    Which of the following statements is true regarding afterload?

    <p>Increased afterload can reduce stroke volume and cardiac output.</p> Signup and view all the answers

    What type of muscle tissue is characterized by having a fast contraction time suitable for quick movements?

    <p>Skeletal Muscle</p> Signup and view all the answers

    Which muscle type is responsible for involuntary control and maintains tension in blood vessels and organs?

    <p>Smooth Muscle</p> Signup and view all the answers

    What is the primary structural difference between skeletal and smooth muscle?

    <p>Skeletal muscle has multinucleated fibers, whereas smooth muscle has single-nucleus cells.</p> Signup and view all the answers

    During the action potential of cardiac muscle, what phase is characterized by Ca2+ influx maintaining depolarization?

    <p>Phase 2</p> Signup and view all the answers

    What is the characteristic of skeletal muscle fibers regarding their arrangement?

    <p>Organized into sarcomeres</p> Signup and view all the answers

    Which statement accurately describes the contraction duration of skeletal muscle compared to smooth muscle?

    <p>Skeletal muscle has a shorter contraction duration than smooth muscle.</p> Signup and view all the answers

    What initiates the calcium release in skeletal muscle contraction?

    <p>Action potential propagation</p> Signup and view all the answers

    Which phase of the skeletal muscle contraction cycle occurs first?

    <p>Calcium binding</p> Signup and view all the answers

    Which component is NOT involved in the relaxation of skeletal muscle?

    <p>Myosin heads</p> Signup and view all the answers

    What is true about the duration of skeletal muscle contraction?

    <p>It lasts only 1-2 milliseconds.</p> Signup and view all the answers

    Which of the following best describes stroke volume?

    <p>Volume of blood ejected per heartbeat</p> Signup and view all the answers

    What does the QRS complex in an ECG represent?

    <p>Ventricular depolarization</p> Signup and view all the answers

    Which of the following factors is NOT associated with regulating stroke volume?

    <p>Heart rate</p> Signup and view all the answers

    How is cardiac output calculated?

    <p>SV × HR</p> Signup and view all the answers

    Study Notes

    Frank-Starling Mechanism and Cardiac Function

    • Greater preload enhances stroke volume (SV) by increasing ventricular filling.
    • Afterload is the resistance the heart must overcome to eject blood; higher afterload decreases SV and cardiac output (CO).

    Skeletal Muscle Characteristics

    • Muscle action potentials are shorter (1-2 milliseconds) without a plateau phase, characterized by rapid depolarization and repolarization.

    Skeletal Muscle Contraction Cycle

    • Action Potential: Initiated at the neuromuscular junction, propagating through T-tubules.
    • Calcium Release: Calcium ions are released from the sarcoplasmic reticulum into the cytoplasm.
    • Calcium Binding: Calcium binds to troponin, shifting tropomyosin to uncover actin-binding sites.
    • Cross-Bridge Cycling:
      • Attachment: Myosin heads attach to exposed actin sites.
      • Power Stroke: Myosin head pivots, pulling actin filament due to ADP release.
      • Detachment: Myosin detaches when ATP binds to it.
      • Reactivation: ATP is hydrolyzed, resetting the myosin head for another cycle.
    • Relaxation: Calcium is taken back into the sarcoplasmic reticulum, covering the actin sites.

    Sarcomere Function

    • Sarcomere: The basic contractile unit of muscle, spanning from one Z-line to the next.
    • Contraction: Sarcomeres shorten as myosin pulls actin filaments inward.
    • Relaxation: Lengthening occurs as cross-bridges detach, returning to resting position.

    ECG Components

    • P Wave: Represents atrial depolarization.
    • QRS Complex: Indicates ventricular depolarization.
    • T Wave: Reflects ventricular repolarization.
    • PR Interval: Duration of atrial to ventricular conduction.
    • ST Segment: Transition phase from ventricular depolarization to repolarization.

    Cardiac Terminology

    • Stroke Volume (SV): Blood volume ejected per heartbeat, influenced by preload, afterload, and contractility.
    • Cardiac Output (CO): Total blood volume pumped by the heart per minute; calculated as CO = SV × Heart Rate (HR).
    • End-Diastolic Volume (EDV): Blood volume in ventricles at the end of the filling phase.
    • End-Systolic Volume (ESV): Blood volume remaining in ventricles post-contraction.
    • Preload: Myocardial stretch degree before contraction, associated with EDV.

    Muscle Type Contraction Characteristics

    • Skeletal Muscle: Fast contraction time, ideal for rapid movements.
    • Smooth Muscle: Slow contraction, providing sustained tension.
    • Cardiac Muscle: Intermediate contraction time, continuous heartbeats.

    Structural Differences between Muscle Types

    Skeletal Muscle

    • Composed of striated, multinucleated fibers, organized into parallel sarcomeres.
    • Functions in voluntary movement and force production.

    Smooth Muscle

    • Comprised of non-striated, single-nucleus cells anchored by dense bodies.
    • Functions under involuntary control; maintains tension in blood vessels and various organs.

    Action Potential Comparison

    Cardiac Muscle

    • Action potentials last longer (200-300 ms) due to a plateau phase.
    • Phases include:
      • 0: Rapid depolarization through Na+ influx.
      • 1: Partial repolarization from K+ efflux.
      • 2: Plateau phase maintained by Ca2+ influx.
      • 3: Repolarization through K+ efflux.
      • 4: Resting membrane potential is established.

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    Description

    Test your understanding of key concepts in cardiovascular physiology, focusing on the Frank-Starling mechanism and the roles of preload and afterload. Discover how these factors influence stroke volume (SV) and cardiac output (CO) in the heart's functioning.

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