cardiovascular

cardiac muscle fibers that dont contract but instead create and conduc the action potential throughout the heart

• ventricular fibers

• contractile fibers

• autorhythmic fibers

• atrial fibers

The P-wave in an electrocardiogram occurs during

• atrial repolarization

• ventricular depolarization

• ventricular repolarization

• atrial depolarization

which structures permit action potentials in the autorhythmic cardiac fibers to move from one cell immediately to an adjacent cell

• gap junctions

• intercalated discs

• tight junctions

• desmosomes

channels in cardiac muscle fiber memebranes in the sinoatrial node that open when a threshold of -40 mV is reached are

• L-type

• T-type

• K+ channels

• F-type sodium channels

what is not part of the conducting system in the heart

• av valve

• sa node

• purkinje fibers

• internodal bundles