Regulation of Heart Function Quiz
30 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What effect does parasympathetic stimulation have on the heart's depolarization phase?

  • It prolongs the time taken to reach depolarization. (correct)
  • It creates a plateau phase.
  • It accelerates depolarization.
  • It increases conduction velocity.

    • Which of the following components is primarily responsible for increasing heart rate upon sympathetic stimulation?

  • PKA.
  • LTCC.
  • cAMP.
  • If channels. (correct)

    • What is the primary effect of parasympathetic stimulation on heart rate?

  • It decreases heart rate. (correct)
  • It maintains heart rate.
  • It increases heart rate.
  • It causes irregular heartbeats.

    • How does the sympathetic nervous system affect conduction velocity in nodal cells?

    <p>It increases conduction velocity. (C)</p> Signup and view all the answers

    What is the primary consequence of increased If activity in the SA node?

    <p>Increased heart rate. (C)</p> Signup and view all the answers

    Which neurotransmitter is secreted during parasympathetic stimulation?

    <p>Acetylcholine (D)</p> Signup and view all the answers

    What role does cAMP play in sympathetic stimulation of nodal cells?

    <p>It activates PKA, enhancing heart activity. (D)</p> Signup and view all the answers

    What law describes the intrinsic regulation of heart function?

    <p>Starling’s law (B)</p> Signup and view all the answers

    What happens to the slope of Phase 4 during sympathetic stimulation?

    <p>It increases. (B)</p> Signup and view all the answers

    What is the effect of sympathetic stimulation on heart rate and contraction force?

    <p>It increases both heart rate and force of contraction. (B)</p> Signup and view all the answers

    Which protein is associated with the positive chronotropic effect in nodal cells?

    <p>PKA. (C)</p> Signup and view all the answers

    Which channel is affected by acetylcholine during parasympathetic control?

    <p>K+/ACh channel (C)</p> Signup and view all the answers

    How does the activity of the If channel affect the heart rate?

    <p>Decreases heart rate by decreasing the Phase 4 slope. (A)</p> Signup and view all the answers

    Which effect best describes the (-) dromotropic effect?

    <p>Slower conduction of action potentials. (D)</p> Signup and view all the answers

    What is primarily lowered during parasympathetic stimulation?

    <p>All of the above. (D)</p> Signup and view all the answers

    What role does norepinephrine play in sympathetic stimulation?

    <p>Increases heart rate and force of contraction. (C)</p> Signup and view all the answers

    Which type of receptors are primarily involved in parasympathetic control on nodal cells?

    <p>m2 muscarinic receptors (A)</p> Signup and view all the answers

    Which neurotransmitters are involved in sympathetic control of nodal cells?

    <p>Epinephrine and norepinephrine. (C)</p> Signup and view all the answers

    What effect does sympathetic stimulation have on cAMP levels in nodal cells?

    <p>Increases cAMP levels. (A)</p> Signup and view all the answers

    What is the physiological response when the heart's K+/ACh channel activity increases?

    <p>Heart rate decreases. (D)</p> Signup and view all the answers

    What effect does sympathetic stimulation have on the heart's conduction velocity?

    <p>Increases conduction velocity (C)</p> Signup and view all the answers

    Which type of agents positively affect contractility in cardiac contractile cells?

    <p>Epinephrine and Norepinephrine (B)</p> Signup and view all the answers

    What is the primary factor that determines heart rate?

    <p>Rate of depolarization in autorhythmic cells (A)</p> Signup and view all the answers

    Which type of effect is associated with changes in heart rate?

    <p>Chronotropic effect (A)</p> Signup and view all the answers

    What is the effect of a positive dromotropic agent on conduction velocity through the AV node?

    <p>Increases conduction velocity (A)</p> Signup and view all the answers

    Which physiological process increases stroke volume during sympathetic stimulation?

    <p>Increased contractility (D)</p> Signup and view all the answers

    What effect does sympathetic stimulation exert on the duration of ventricular diastole?

    <p>Decreases duration of diastole (C)</p> Signup and view all the answers

    How does the intrinsic regulation of the heart differ from extrinsic regulation?

    <p>Intrinsic regulation is controlled by the heart's own pacemaker cells (C)</p> Signup and view all the answers

    Which protein inhibits the SERCA2 pump in cardiac contractile cells?

    <p>Phospholamban (B)</p> Signup and view all the answers

    What is the relationship between venous return and stroke volume during sympathetic activation?

    <p>Increased venous return increases stroke volume (C)</p> Signup and view all the answers

    Flashcards

    Intrinsic heart regulation

    Heart function regulated by its inherent characteristics, not external factors like nerves or hormones.

    Extrinsic heart regulation

    Heart function regulated by nerves and hormones.

    Starling's Law of the Heart

    The heart's ability to adjust its output based on the volume of blood entering it.

    Parasympathetic stimulation

    Heart rate slowed by the vagus nerve, releasing acetylcholine.

    Signup and view all the flashcards

    Sympathetic stimulation

    Increases heart rate and contraction force via cardiac nerves, releasing epinephrine and norepinephrine.

    Signup and view all the flashcards

    Vagus nerve

    A nerve that slows down the heart rate.

    Signup and view all the flashcards

    Acetylcholine

    Neurotransmitter that slows heart rate.

    Signup and view all the flashcards

    Epinephrine/Norepinephrine

    Neurotransmitters that increase heart rate and strength of contraction.

    Signup and view all the flashcards

    Chronotropic effect

    Effect on heart rate.

    Signup and view all the flashcards

    Cardiac Nerves

    Nerves carrying signals to regulate heartbeat.

    Signup and view all the flashcards

    What does a positive chronotropic effect do?

    A positive chronotropic effect increases heart rate.

    Signup and view all the flashcards

    What does a negative chronotropic effect do?

    A negative chronotropic effect decreases heart rate.

    Signup and view all the flashcards

    What does a negative dromotropic effect do?

    A negative dromotropic effect decreases conduction velocity through the heart.

    Signup and view all the flashcards

    What is the effect of sympathetic stimulation on cardiac contractile cells?

    Sympathetic stimulation increases contractility by activating the Gs protein pathway, which leads to increased calcium release and uptake by the SR, ultimately enhancing the force of contraction.

    Signup and view all the flashcards

    What is an inotropic effect?

    An inotropic effect influences the contractility of the heart.

    Signup and view all the flashcards

    What is the relationship between stroke volume and heart rate?

    Stroke volume and heart rate are the two factors that determine cardiac output.

    Signup and view all the flashcards

    How does venous return affect stroke volume?

    Increased venous return increases end-diastolic volume, which in turn increases stroke volume.

    Signup and view all the flashcards

    How does sympathetic innervation and epinephrine influence cardiac contractility?

    Sympathetic innervation and epinephrine increase contractility by activating the Gs protein pathway, leading to increased calcium release and uptake by the SR, ultimately enhancing the force of contraction.

    Signup and view all the flashcards

    LTCC Activity in Phase 0

    LTCC activity has a slower depolarization rate, leading to a decreased conduction velocity in Phase 0.

    Signup and view all the flashcards

    Parasympathetic Control on the Heart

    Parasympathetic stimulation hyperpolarizes the membrane potential and slows down depolarization in the heart, reducing heart rate.

    Signup and view all the flashcards

    Sympathetic Control on Nodal Cells

    Sympathetic control on nodal cells activates Gs protein, increasing cAMP, and activates PKA.

    Signup and view all the flashcards

    If Activity (funny current)

    Increased If activity from sympathetic control causes faster reaching of the threshold in phase 4 and increased heart rate.

    Signup and view all the flashcards

    Phase 4 Slope

    Phase 4 slope refers to the rate at which the membrane potential rises in Phase 4.

    Signup and view all the flashcards

    Membrane Potential

    The difference in electrical charge across a cell's membrane.

    Signup and view all the flashcards

    Heart Rate (HR)

    The number of times the heart beats per minute.

    Signup and view all the flashcards

    Threshold (VT)

    The critical level of membrane potential that initiates an action potential.

    Signup and view all the flashcards

    Study Notes

    Regulation of Heart Function

    • Intrinsic regulation arises from the normal functioning of the heart, independent of neural or hormonal control.
    • Starling's Law of the Heart is a key concept in intrinsic regulation.
    • Extrinsic regulation involves controlling the heart via neural and hormonal signals.
    • Parasympathetic stimulation, mediated by the vagus nerve, slows heart rate by releasing acetylcholine.
    • Sympathetic stimulation, via cardiac nerves, increases heart rate and contractility by releasing epinephrine and norepinephrine.
    • Cardiac innervation: Parasympathetic and sympathetic pathways regulate the heart's rhythm and contractility.

    Parasympathetic Control on Nodal Cells

    • Parasympathetic activity reduces the slope of phase 4, hyperpolarizing nodal cells and slowing heart rate.
    • It increases potassium channel activity and thus, reduces heart rate.
    • This decreases the rate of spontaneous depolarization (phase 4) and prolongs the time to reach threshold.
    • The slowed depolarization decreases heart rate and conduction velocity.

    Sympathetic Control on Nodal Cells

    • Sympathetic activity increases the slope of phase 4, speeding up the heart rate.
    • It enhances the activity of the If channel, leading to a faster rate of spontaneous depolarization.
    • This faster depolarization leads to faster heart rate and conduction velocity.

    Extrinsic Regulation: Parasympathetic Control

    • Parasympathetic stimulation causes a hyperpolarized state.
    • The depolarization phase becomes slower compared to the normal heart rate.

    Extrinsic Regulation: Sympathetic Control

    • Sympathetic stimulation causes a steeper and faster depolarization phase.

    Types of Effects: Chronotropic Effect

    • Chronotropic effect relates to changes in heart rate.
    • Increased sympathetic stimulation leads to an increase in heart rate (positive chronotropic).
    • Parasympathetic stimulation leads to a decrease in heart rate (negative chronotropic).

    Types of Effects: Dromotropic Effect

    • Dromotropic effects involve changes in conduction velocity across the heart.
    • Sympathetic stimulation speeds up conduction.
    • Parasympathetic stimulation slows conduction.

    Types of Effects: Inotropic Effect

    • Inotropic effects modify cardiac contractility.
    • Positive inotropic effect increases contractility (eg. Epinephrine, Norepinephrine).
    • Negative inotropic effect decreases contractility (eg. certain chemicals).

    Stroke Volume and Heart Rate

    • Stroke volume is the volume pumped by the heart with each beat.
    • Heart rate is the number of beats per minute.
    • Cardiac output is the product of stroke volume and heart rate.
    • Factors affecting stroke volume include contractility, end-diastolic volume, and venous return.
    • Factors affecting heart rate include sympathetic and parasympathetic inputs.

    Wiggers Diagram

    • A graphical representation of the cardiac cycle, showing relationships between pressure, volume, and electrical activity.
    • The diagram illustrates the phases of the cardiac cycle and the associated changes in ventricular pressure, volume, and electrical activity.
    • Shows the relationship between heart sounds, electrical signals, pressure, and volume changes within the heart during one cardiac cycle.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Lecture 15 Regulation of Heart Function PDF

    Description

    Test your understanding of heart function regulation, focusing on intrinsic and extrinsic controls. Explore concepts like Starling's Law and how the autonomic nervous system affects heart rate and contractility. Dive into the details of parasympathetic and sympathetic control of cardiac activity.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser