Basic ECG Interpretation (A+ Graded)

Automaticity correct answers The ability to act as an impulse, initiating electrical activity and spontaneous depolarization (this is the most important difference between cardiac and skeletal muscle cells) Excitability correct answers The ability to respond to a stimulation and initiate an impulse Conductivity correct answers The ability to transmit an impulse that has been initiated and passes along cell membrane Refractoriness correct answers The inability of a muscle cell fiber to respond to a stimulus during an interval following contraction Cardiac Conduction correct answers 1. SA Node 2. Internodal pathways 3. AV node 4. Bundle of His 5. Right and left bundle branch 6. Purkinje Fibers Sinoatrial Node correct answers A small cluster of cells located in the upper right atrium Is it the pacemaker of the heart and inherent (normal) rate is 60 to 100 beats per minute Internodal pathways correct answers Impulses sent by the SA node travel through the atrial muscle fibers via the intra-atrial pathways This allows for simultaneous depolarization and contraction of the atria Atrioventricular (AV) Node correct answers Located in the lower portion of the right atrium It receives impulse from the SA node and delays the conduction to allow for the atria to contract Then conducts to the ventricle Bundle of His correct answers Lies in the upper part of the intraventricular septum and connects the AV node with the bundle branches in the ventricles The AV node and Bundle of His are collectively known as the Junctional Area or AV Junction Inherent rate is 40-60 and is th back-up system for the SA node Right Bundle Branch correct answers Arise from the Bundle of His and travel down the right side of the septum Left Bundle Branch correct answers Arise from the Bundle of his and travel down the left side of the septum Branches off into two sections because the left ventricle is much larger than the right ventricle Purkinje Fibers correct answers Smaller branches of the bundle branches Spread throughout the myocardium of the ventricles and terminate there