Electrical Activity and Muscles of the Heart Flashcards
ability to initiate an electrical potential at a fixed rate that spreads rapidly from cell to cell to trigger the contractile mechanism.
autorhythmicity
About 99 percent of the cells in the atria and ventricles. They conduct impulses and contractions.
Myocardial Contractile Cells
About 1 percent of the cells in the atria and ventricles. They form the conduction system besides the Purkinje Fibers
Myocardial Conductive Cells
A junction between two adjoining cells in the heart
Intercalated Disc
Normal Cardiac Rythm is made from this node. Located in the Superior and Posterior Right Atrium close to the orifice of the Superior Vena Cava
Sinoatrial Node (SA)
Sinoatrial Node (SA) is considered what of the heart
Pacemaker
The Sinoatrial Node initiates what rhythm
Sinus Rhythm or Normal Electrical Activity
impulse spreads from its initiation in the SA node throughout the atria through specialized
Internodal Pathways
Special pathway that conducts electrical impulse directly from the right atrium to the left atrium
Bachmanns Bundle or Interatrial band
Specialized conductive cells located in the inferior portion of the right atrium, within the atrioventricular septum.
Atrioventricular Node (AV)
What arises from the Atrioventricular Node (AV)
Atrioventricular Bundle or Bundle of His
From the Bundle of His, what is proceeded from the interventricular Septum
Atrioventricular Bundle Branches (Left and Right Bundle Branches)
Additional myocardial conductive fibers that spread the impulse cells to the contractile cells in the ventricles
Purkinje Fibers
Conductive cells contain a series of sodium ion channels that allow a normal and slow influx of sodium ions that causes the membrane potential to rise slowly from an initial value of −60 mV up to about –40 mV. The resulting movement of sodium ions creates
creates spontaneous depolarization (Prepotential depolarization)
influx through slow calcium channels accounts for the prolonged plateau phase and absolute refractory period that enable cardiac muscle to function properly.
Calcium Ions
Tracing of electrical signals in the heart
Electrocardiogram (EKG)
Depolarization of the Atria in an ECG
P wave
Depolarization of the Ventricles in an ECG
QRS Complex
Repolarization of the Ventricles
T Wave
Where does the repolarization of the atrium occur in an ECG?
QRS Complex
Interruption of a normal conduction pathway
Heart Block
Device that delivers electrical impulses to the heart muscle to ensure that the heart is contracting and pumping blood effectively
Artificial Pacemaker
