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Chapter 20: Heart (Conducting System)

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  • Heartbeat

    the coordinated action of all 4 chambers of the heart;

    atria then the ventricles

  • Which types of cardiac muscle cells are involved in the beating of the heart?

    Autorhythmic and Contractile

  • Autorhythmic Cells

    Pacemaker and conducting cells;

    initiate and distribute electrical signals to keep heart cells contracting at an appropriate pace.

  • Contractile Cells

    produce contractions that push blood through the body

  • Autorhythmicity

    ability of the cardiac muscle tissue to contract without neural or hormonal stimulation

  • Pacemaker cells are found in...

    the SA and AV nodes

  • Sinoatrial (SA) Nodes

    in the wall of the R. atrium; the primary pacemaker

  • Atrioventricular (AV) Nodes

    in the junction between atria and ventricles

  • Conducting cells are found in...

    Internodal pathways(in atrial walls), AV bundle, bundle of branches, and Purkinje fibers

  • Internodal Pathways distribute

    the stimulus to the atrial muscle cells when it travels from SA to AV node

  • The AV bundle, bundle branches, and Purkinje fibers do what?

    Relay stimulus info through to the ventricles

  • Pacemaker Potential

    gradual depolarization of pacemaker cells due to slow inflow of sodium ions

  • Rate of spontaneous depolarization for each node is how many action potentials/minute

    SA node = 60 -100 ap's per minute

    AV node = 40-60 ap's per minute

  • The SA node establishes the

    sinus rhythm/basic heart rhythm

  • Pathway of the Conducting System

    SA node (generate action potent.)--> Internodal Pathways (stimulus travels) --> AV node (atria contracts; delayed impulse for 100 msec) --> Bundle of Branches --> Purkinje Fibers ---> Contractile cells

  • Parasympathetic stimulation ____ the heart rate and Sympathetic stimulation _____ the heart rate

    slows; speeds up