Chapter 4- EKG's and Interpretation and Management of Basic Dysrhythmias
Questions And Answers
cardiac electrophysiology - CORRECT ANSWER-study of the
... [Show More] electrical properties of the cardiac muscle
-electricity flows through the heart in a regular, measured pattern and results in contraction of the
cardiac muscle
-electrical activity precedes mechanical activity (contraction of the heart)
-EKG looks at the electrical activity
properties of cardiac cells - CORRECT ANSWER-specialized cardiac cells have unique characteristics that
allow them to regulate heart rate and rhythm
characteristics include:
-automaticity
-excitability
-conductivity
-contractility
automaticity - CORRECT ANSWER-ability of cardiac pacemaker cells to spontaneously initiate the
electrical impulse
-if there is a block in the heart or impulse, other areas take over so the heart doesn't stop (like a defense
mechanism)
-sinoatrial node (SA), is the pacemaker of the heart and goes at a rate of 60-100 bpm
-atrioventricular (AV) junction (can initiate a rate of 40-60 bpm)
-bundle of HIS
-purkinje fibers (goes at 20-40 bpm which is not sustainable for CO but enough to get help)
excitability - CORRECT ANSWER-refers to the ability of cardiac cells to respond to an electrical impulse
generated by pacemaker cells or other external stimuli
-depolarization occurs when cells become electrically excited
conductivity - CORRECT ANSWER-the ability of the cardiac cells to transmit the electrical impulse to
adjacent cardiac cells (the next cell)
-wave of depolarization creates the deflections seen on the electrocardiogram (ECG)
contractility - CORRECT ANSWER-the ability of the cardiac cells to shorten in response to electrical
stimulation; a mechanical event (when they contract)
cardiac action potential - CORRECT ANSWER-refers to the change in the electrical charge inside the
cardiac cell when it is stimulated
-movement of electrolytes such as sodium, potassium, calcium assist the heart to get good contraction
to push blood
polarization - CORRECT ANSWER-electrical state at the cardiac cell membrane when the cell is at rest
-no electrical activity is occurring
-ECG displays a flat, isoelectric line
depolarization - CORRECT ANSWER-opposite of polarization
-on the ECG, the P wave represents atrial depolarization and the QRS represents ventricular
depolarization
-electrical event that results in a contraction of cardiac muscle, a mechanical event (atrial/ventricular
contraction); happens seamlessly in a beating heart [Show Less]