Chapter 4 & 5 Flashcards
Firing rate of the SA node
60-100 BPM
Commonly referred to as the primary pacemaker of the heart because it normally depolarizes more rapidly than any other part of the conduction system
SA node (sinoatrial node)
Distribute the electrical impulse throughout the atria and transmit the impulse from the SA node to the AV node
Internodal tracts
A subdivision of the anterior internodal tract, conducts electrical activity from the SA node to the left atrium
Bachmann’s bundle
Located on the floor of the right atrium near the coronary sinus and just above the tricuspid valve
AV node
In the AV node electrical activity is delayed approximately
.05 seconds allows for more complete filling of ventricles
The AV node is the secondary pacemaker and fires at
40-60 BPM
Purkinje’s network firing rate is
20-40 BPM
The region where the AV node joins the bundle of His
AV junction
The pathway that leads out of the AV node and is also traditionally referred to as the common bundle
Bundle of His
Two main branches,the right bundle and the left bundle. Conduct electrical activity from the bundle of His down into the Purkinje network
Bundle branches
A network of fibers that carries electrical impulses directly to ventricular muscle cells
Purkinje’s network
Normal conduction pattern of the heart
SA node, Internodal pathways, AV node, Bundle of His, Bundle branches, Purkinje fibers
Placement of bipolar lead #1
Positive on left arm, negative on right arm
Placement of bipolar lead #2
Positive on left leg, negative on right arm
Placement of bipolar lead #3
Positive on left leg, negative on right arm
Abnormal heart rhythms
Dysrhythmias
Each small square represents _________ in height
1mm
Each small square on a graph represents _________ seconds
.04
A large box in the darker lines on the graph represent ____ seconds
.20
The straight line seen on an EKG strip, represents the beginning and end point of all waves
Baseline
Represents depolarization of the left and right atria
P wave
Represents the time interval necessary for the impulse to travel from the SA node through the internodal pathways in the atria and downward to the ventricles
PR interval
The P wave is approximately _________ in length
.10 seconds
Normal PR interval is measured from the _________ to the ______________
Beginning of the P wave to the beginning of the QRS complex
The normal PR interval is measured as __ to ___ small squares and is approximately ____ to _____ seconds in length
3 to 5 squares and .12 to .20 seconds
Represents the conduction of the electrical impulse from the bundle of His throughout the ventricular muscle, or ventricular depolarization
QRS complex
Normal QRS complex measures __________________ or _________________
Less than .12 seconds or less than three small squares on EKG paper
The time interval during which the ventricles are depolarized and ventricular repolarization begins
ST segment
Represents ventricular repolarization and follows the ST segment
T wave
