Chapter 16 Flashcards
Describe P wave, QRS complex, T wave, U wave
p wave = depolarization of muscle cells
QRS complex = depolarization of ventricular muscle cells
T wave = ventricular muscle repolarizes
u wave = not always seen, but follows T wave
repolarization
myocardial muscle cells relax
what is the sodium potassium ion pump?
when a cell is stimulated, movement of ions in and out of the membrane alters its charge, reversing resting potential
fibrillation
quivering contraction of cardiac muscle fibers
automaticity
cardiac cell membranes spontaneously depolarize at recurrent periods
cardiac cycle
events that occur from the beginning of one ventricular contraction (systole) until the beginning of another
what are the five steps in the analysis of an ECG?
is rhythm regular?
are all QRS’s similar?
Are all P waves similar?
is rate normal?
do waves and complexes proceed in normal sequence?
what are unique features to the tissue of the cardiac neural conductive system?
allows cell membranes to spontaneously depolarize
cell membranes are in direct contact with cardiac muscle, and action potential initiaes depolarization
cardiac output
amount of blood ejected from the ventricles each minute
depolarization
myocardial cells are stimulated to contract
what indicates an AV block?
longer intervals indicate that the impulse is being delayed from entering the ventricles
what are the classic events required for a normal cardiac cycle?
rhythmic contraction and relaxation of the chambers of the heart, atria, and the ventricles
what is one of the most common cardiac arrhythmias?
atrial fibrillation
what happens when the QRS complex is wide?
an extra impulse is fired, PVC
what are the two principal cell types of the heart and examples?
working cardiac cells (cardiac muscle, myocardium of atria and ventricles)
specialized neural conductive (SA node, AV node, bundle of HIS, purkinjie fibers)
action potenial
process of depolarization and repolarization of the cardiac membrane
what is known as the pacemaker of the heart?
SA node
what is the purpose of the heart?
to pump blood through vessels to vital organs and tissues
what is the baseline of an ECG called?
isoelectric line
what are deflections in an ECG?
positive/negative changes in the tracing relative to the isocenter over the time of the cycle
arrhythmia
irregularity of cardiac actions associated with physiologic or pathologic interruption of the neuro conductive tissues of the heart
assessment of the hearts ability to perform its vital function is possible using what?
electrocardiogram
asystole
no evidence of any cardiac neuro conductive activity (cardiac arrest)
how is ventricular fibrillation seen on an ECG?
twitch and quiver
