exercise 14 Flashcards
ECG
the sum of all the electrical activity that occurs in one cardiac cycle
myogenic
activity is initiated by the heart itself
autorhythmic
sets its own rate, which can be modified by the autonomic system; SA node
SA node
pacemaker
normal sinus rhythm
originates in SA node; usually 60-100 bpm
tachycardia
above 100 bpm
bradycardia
below 60 bpm
sinus arrythmia
when there is a variation in the P-P interval of 120 ms or more in a person w normal P waves or a change of at least 10% between the shortest and longest P-P intervals
P wave
atrial depolarization; AP spreads through atria to result in atrial depolarization; leads to atrial systole (contraction)
QRS complex
AP is conducted through bundle of His, the right and left bundle branches, and the Purkinje fibers to ventricles resulting in ventricular depolarization; ventricular systole
T wave
ventricles depolarize; ventricule diastole
isoelectric line
no electrical activity is being generated in the heart
P-R interval
beginning of P-wave to beginning of QRS complex; interval btwn the activation of the SA node and activation of the AV node
P-R segment
end of P-wave to the beginning of the QRS complex; it is the interval between atrial depolarization and ventricular depolarization
S-T segment
end of S wave to beginning of T wave; should be an isoelectric line because the ventricles are uniformly excited and there is no change in charge. corresponds to the plateau phase in the ventricular muscle cell action potential
