C-CARDIAC ACTION POTENTIALS Flashcards Preview

zz CVPR > C-CARDIAC ACTION POTENTIALS > Flashcards

Flashcards in C-CARDIAC ACTION POTENTIALS Deck (24):
1

Cells in the sinoatrial node and AV node are capable of spontaneous _________

depolarization

2

CONTRACTILE MYOCYTE is activated by

outside signal (AP)

3

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

4

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.

gap junctions

5

The AV node does not have _____ making it a poor conductor and causes a delay

Na Channels

6

The sinoatrial (SA) node has automaticity and normally is the ______ generating
the electrical signal that starts a wave of depolarization

pacemaker

7

depolarization wave goes from SA through the right and then the left atrium generating the _______.

P wave

8

Post P wave arrives at the ___________ located between the fibrous tricuspid and mitral valve rings that separate the atria from the
ventricles

atrioventricular (A-V) node

9

P wave =

atrial depolarization

10

QRS =

ventricular repolarization

11

T wave =

ventricular repolarization

12

PR interval =

index of conduction time across the AV node

13

QT interval =

total duration of depolarization and repolarization

14

Improper beating of the heart, whether irregular, too fast, or too slow

Arrhythmia

15

3 COMMON MECHANISMS LEADING TO ARRHYTHMIA

Abnormal reentry pathways
Ectopic foci
In triggered activity abnormal “after polarizations”

16

If the activation wave is toward a sensing electrode
a _________ deflection will be recorded

positive (upward)

R wave

17

The greater the muscle mass the greater the ______

voltage recorded

18

The SA node is high in the right atrium and the depolarization wave sweeps ______

downward and leftward.

19

The QRS and T waves will be

in the same direction in every lead

20

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

21

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.

22

When the right bundle is blocked -

QRS widening with delayed conduction to the right ventricle

23

When the left bundle is blocked –

QRS widening with delayed conduction to the left ventricle

24

When left bundle fascicles are blocked there are....

shifts in direction of depolarization but no QRS widening.