Flashcards in C-CARDIAC ACTION POTENTIALS Deck (24):
Cells in the sinoatrial node and AV node are capable of spontaneous _________
CONTRACTILE MYOCYTE is activated by
outside signal (AP)
In phase 4 (AV/SA) there is slow depolarizing due to a “funny/pacemaker current” until it reaches a critical voltage where a more rapid Phase 0 occurs due entirely to a ______
calcium current – no fast sodium current is present.T
Once an electrical impulse is initiated by a pacemaker it will spread rapidly through the__________, cylindrical structures formed by connexins that allow ions to pass from cell to cell.
The AV node does not have _____ making it a poor conductor and causes a delay
The sinoatrial (SA) node has automaticity and normally is the ______ generating
the electrical signal that starts a wave of depolarization
depolarization wave goes from SA through the right and then the left atrium generating the _______.
Post P wave arrives at the ___________ located between the fibrous tricuspid and mitral valve rings that separate the atria from the
atrioventricular (A-V) node
P wave =
T wave =
PR interval =
index of conduction time across the AV node
QT interval =
total duration of depolarization and repolarization
Improper beating of the heart, whether irregular, too fast, or too slow
3 COMMON MECHANISMS LEADING TO ARRHYTHMIA
Abnormal reentry pathways
In triggered activity abnormal “after polarizations”
If the activation wave is toward a sensing electrode
a _________ deflection will be recorded
The greater the muscle mass the greater the ______
The SA node is high in the right atrium and the depolarization wave sweeps ______
downward and leftward.
The QRS and T waves will be
in the same direction in every lead
There are 3 types of AV block
1a block: conduction delayed but all P waves conduct to the ventricles.
2a block: some P waves conduct but others do not
3a block: none of the P waves conduct & a ventricular pacemaker takes over
SA (sinoatrial node) abnormalities:
cause “sick sinus syndrome” resulting in slow sinus rates or takeover by other pacemakers which may be either fast or slow.
When the right bundle is blocked -
QRS widening with delayed conduction to the right ventricle
When the left bundle is blocked –
QRS widening with delayed conduction to the left ventricle