EKG Basic Principles Flashcards
info on EKG represents heart’s ____ activity
electrical
most information on EKG represents electrical activity of ____ of myocardium
contraction
when myocardium is electrically stimulated, it ____
contracts
while in the resting state, myocytes are POLARIZED, the interior of every cell are ____-ly charged
negative
the interiors of resting myocytes are NEGATIVE, but when these cells are DEPOLARIZED, their interiors become ____ and the cells contract
positive
“depolarization” moves as a wave through the myocardium; as this wave of DEPOLARIZATION stimulates the heart’s myocytes, they become positive and ____
contract
depolarization may be considered an advancing wave of ____ charges w/i the heart’s myocytes
positive
advancing wave of depolarization causes progressive contraction of myocardium as this wave of ____ charges passes through the interiors of myocytes
positive
stimulating wave of depolarization makes the interiors of myocytes ____ and stimulates them to contract
positive
myocyte interiors regain their resting negative charge during the ____ phase that follows
repolarization
myocardial contraction is caused by ____ of myocytes, which records on on the EKG as shown above; the recovery phase that follows depolarization is known as ____
depolarization
repolarization
both depolarization and repolarization of the myocardium are ____ phenomena caused by movement of ions
electrical
a wave of depolarization advancing through myocardium is a moving wave of ____ charges
positive
when a wave of POSITIVE charges (Na+ ions) moves TOWARDS a POSITIVE electrode, there is a simultaneous ____ deflection
UPWARD
heart’s dominant pacemaker
SA node
SA node location
upper-posterior wall of right atrium
SA node stimulates both atria to ____
contract
ability of SA node to generate pacemaking stimuli is known as ____
automaticity
atrial depolarization is recorded as a ____ wave on EKG
P
P wave represents
atrial depolarization
sole electrical pathway from atria to ventricles
AV node
mitral and tricuspid valves act to electrically ____ the ventricles from the atria
insulate
because depolarization slows w/i the AV node, there is a brief ____ before depolarization is conducted to the ventricles
pause
brief pause allows blood from atria to pass the AV valves and into the ____
ventricles
depolarization shoots rapidly through the ventricular conduction system beginning in the ____
His bundle
His bundle splits into ____
left and right branches
His bundle and both bundle branches are “bundles” of ____
rapidly conducting Purkinje fibers
like myocardium, Purkinje fibers use fast-moving ____ for the conduction of depolarization
Na+ ions
Purkinje fibers terminate in tiny filaments that directly ____ the ventricular myocytes
depolarize
____ represents the beginning of ventricular contraction
QRS complex
first downward deflection of QRS complex
Q wave
Q wave can often be ____ on EKG
absent
Q wave is followed by upward ____
R wave
upward R wave is followed by downward ____
S wave
horizontal segment of baseline following QRS complex
ST segment
ST segment represents
initial (“plateau”) phase of ventricular repolarization
T wave represents
final (“rapid”) phase of ventricular repolarization
repolarization (both, initial and final, phases) is accomplished by ____ leaving the myocytes
K+ ions
ventricular systole lasts from ____ until
beginning of QRS
end of T wave
represents the duration of ventricular systole
QT interval
