C-CARDIAC ACTION POTENTIALS

Question 1

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

Answer 1

depolarization

Question 2

CONTRACTILE MYOCYTE is activated by

Answer 2

outside signal (AP)

Question 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 ______

Answer 3

calcium current – no fast sodium current is present.T

Question 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.

Answer 4

gap junctions

Question 5

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

Answer 5

Na Channels

Question 6

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

Answer 6

pacemaker

Question 7

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

Answer 7

P wave

Question 8

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

Answer 8

atrioventricular (A-V) node

Question 9

P wave =

Answer 9

atrial depolarization

Question 10

QRS =

Answer 10

ventricular repolarization

Question 11

T wave =

Answer 11

ventricular repolarization

Question 12

PR interval =

Answer 12

index of conduction time across the AV node

Question 13

QT interval =

Answer 13

total duration of depolarization and repolarization

Question 14

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

Answer 14

Arrhythmia

Question 15

3 COMMON MECHANISMS LEADING TO ARRHYTHMIA

Answer 15

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

Question 16

If the activation wave is toward a sensing electrode

a _________ deflection will be recorded

Answer 16

positive (upward)

R wave

Question 17

The greater the muscle mass the greater the ______

Answer 17

voltage recorded

Question 18

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

Answer 18

downward and leftward.

Question 19

The QRS and T waves will be

Answer 19

in the same direction in every lead

Question 20

There are 3 types of AV block

Answer 20

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

Question 21

SA (sinoatrial node) abnormalities:

Answer 21

cause “sick sinus syndrome” resulting in slow sinus rates or takeover by other pacemakers which may be either fast or slow.

Question 22

When the right bundle is blocked -

Answer 22

QRS widening with delayed conduction to the right ventricle

Question 23

When the left bundle is blocked –

Answer 23

QRS widening with delayed conduction to the left ventricle

Question 24

When left bundle fascicles are blocked there are….

Answer 24

shifts in direction of depolarization but no QRS widening.