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111 Cards in this Set

  • Front
  • Back
When at rest, do cardiac cells hold a positive or negative electrical charge?
Negative
How do resting cardiac cells maintaing their polarity?
Membrane Pump
Name the process by which cardiac cells dramatically lose their resting polarity.
Depolarization
Name the process by which cardiac cells regain their resting polarity?
Repolarization
Name the three types of cells that make up the heart.
Packemaker Cells
Electrical Conducting Cells
Myocardial Cells
Name the process of one electrical cycle of depolarization and repolarization of a single cell.
Action Potential
True or False:
Unlike typical cells, a cardiac pacemaker cell does NOT have a true resting potential.
TRUE
The charge of a cardiac pacemaker cell rises from a minimal negative potential which it maintains for just a moment prior to depolarization, but it does not rest there.
The dominant pacemaker cells in the heart located high up in the right atrium.
Sinoatrial Node
(aka: SA Node or Sinus Node)
Region of intra-atrial septum that allows for rapid activation of the left atrium from the right.
Bachman's bundle
Contractile proteins contained within myocardial cells.
actin and myosin
Process of cellular contraction upon depolarization in which calcium plays a key role.
Excitation-contraction coupling
Depolarization causes what element to be released within the myocardial cell.
Calcium
True or False:
Myocardial conduction is slower than electrical conducting cell conduction.
True
Electrical current flows through myocardial cells less effeciently that it does through cardiac conduction cells.
Name the three chief characteristics of EKG waves.
Duration
Amplitude
Configuration (morphology)
Size of small squares on EKG paper
1 x 1 mm
Size of large squares on EKG paper
5 x 5 mm
Horizontal duration of small squares on EKG paper
0.04 seconds
Horizontal duration of large squares on EKG paper
0.2 seconds
Number of small squares per length of a large square on EKG paper.
5
Vertical amplitude of one small square on EKG paper
0.1 mV
Vertical amplitude of one large square on EKG paper
0.5 mV
Verticle amplitude of two large squares on EKG paper
1 mV
Horizontal duration of five large squares on EKG paper
1 second
True or False:
Sinus node firing is visible on EKG.
False
While the associated firing of the atria are visible as a P-wave, in fact the sinus node itself does not produce a large enough signal to be visible on EKG.
True or False:
The P-wave is the sinus node firing.
False
The right side of the P-wave corresponds with the right atrium firing; the left side of the P-wave corresponds with the left atrium. Sinus node firing itself is actually not visible on EKG.
True of False:
In a healthy heart, atrial depolarization is blocked from transmission to the ventricles by the heart valves between the atria and ventricles.
True
In a healthy heart, depolarization can only proceed to the ventricles through the AV node at the top of the septum.
True or False:
Both the SA node and the AV node are under the influence of the autonomic nervous system.
True
Name the three main parts of the ventricular conduction system.
Bundle of His
Bundle Branches
Terminal Purkinje Fibers
Name the three segments of the left bundle branch.
Septal Fascicle
Anterior Fascicle
Posterior Fascicle
Name of EKG deflection that represents ventricular depolarization.
QRS Complex
If the first deflection is downward, what is it called?
Q wave
What is the first upward deflection called?
R wave
If there is a second upward deflection, what is it called?
R-prime
What is the first downward deflection following an upward deflection called?
S wave
If the entire configuration consists of only one downward deflection, what is it called?
QS wave
What are two upward deflections called?
RSR
Small, discreet negative deflection that indicates septal depolarization.
Q wave
Ventricular repolarization wave
T wave
True or False:
There is no such thing as an atrial repolarization wave.
False
There is an atrial repolarization wave, but it is generally hidden behind the more prominent QRS complex.
What measures the time from the start of atrial depolarization to the start of ventricular depolarization?
PR interval
What measures the time from the end of atrial depolarization to the start of ventricular depolarization?
PR segment
What records the time from the end of ventricular depolarization to the start of ventricular repolarization?
ST segment
What measures the time from the start of ventricular depolarization to the end of ventricular repolarization?
QT interval
What measures the time of ventricular depolarization?
QRS interval
What kind of deflection is produced by a wave of depolarization moving toward a positive electrode?
a positive deflection
What kind of deflection is produced by a wave of depolarization moving away from a positive electrode?
a negative deflection
What kind of deflection is produced by a wave of repolarization moving away from a positive electrode?
a positive deflection
What kind of deflection is produced by a wave of repolarization moving toward a positive electrode?
a negative deflection
How many electrodes are used to provide the basis for the six limb leads?
four
(two arm/two leg)
What are the two kinds of limb leads?
Standard Leads (3)
Augmented Leads (3)
What are the leads that are positioned around the horizontal plane of the heart called?
Precordial Leads (6)
On which plane do the limb leads view the heart's electrical activity?
Frontal Plane
On which plane do the precordial leads view the heart's electrical activity?
Horizontal (Transverse) Plane
On the frontal plane, are superiorly oriented angles of orientation expressed in positive or negative degrees?
Superior is Negative
On the frontal plane, are inferiorly oriented angles of orientation expressed in positive or negative degrees?
Inferior is Positive
Each lead has its own specific view of the heart, called what?
Angle of Orientation
An angle of orientation can be determined by drawing a line from what to what?
from a negative to
a positive electrode
Name the three standard limb leads.
Lead I
Lead II
Lead III
Which lead is created by making the left arm positive and the right are negative?
Lead I
What is the angle of orientation for Lead I?
0 degrees
Which lead is created by making the legs positive and the right arm negative?
Lead II
What is the angle or orientation of Lead II?
60 degrees
Which lead is created by making the legs positive and the left arm negative?
Lead III
What is the angle of orientation of Lead III.
120 degrees
With respect to the three augemented limb leads, what does the term 'augmented' refer to?
EKG machine must amplify (augment)the tracings of these three leads to get an adequate recording.
Which lead is created by making the left arm positive and the rest of the limbs negative?
AVL
What is the angle of orientation of AVL?
Negative 30 degrees
Which lead is created by making the right arm positive and the rest of the limbs negative?
AVR
What is the angle of orientation of AVR?
Negative 150 degrees
Which lead is created by making the legs positive and the arms negative?
AVF
What is the angle of orientation of AVF?
90 degrees
Name the inferior leads.
II, III, AVF
Name the left lateral leads.
I, AVL, V5, V6
Name the anterior leads.
V1, V2, V3, V4
Which lead runs superiorly and to the right?
AVR
Precordial leads view the electrical activity of the heart on which plane?
horizontal plane
Which lead is placed in the fourth intercostal space to the right of the sternum.
V1
Which lead is placed in the fourth intercostal space to the left of the sternum.
V2
Which lead is placed in the fifth intercostal space in the midclavicular line?
V4
Which lead is placed in the fifth intercostal space in the midaxillary line?
V6
What is the correct placement of the V3 lead?
between V2 and V4
What is the correct placement of the V5 lead?
between V4 and V6
What part of the heart do the V1 and V2 leads lie directly over?
right ventricle
What part of the heart do the V3 and V4 leads lie directly over?
septum
What part of the heart do the V5 and V6 leads lie directly over?
left ventricle
True or False:
The vector's angle of orientation represents the average direction of current flow.
True.
The EKG electrode records only the average current flow at any given moment.
The amplitude of a P-wave does not normally exceed this value in any lead.
0.25 mV
(2.5 mm or 2.5 small squares)
Normal range of the P-wave vector
0-70 degrees
Normal duration of the PR interval
0.12 to 0.2 seconds
(3 to 5 mm on EKG paper)
Which portion of the heart is the first to depolarize during ventricular depolarization?
interventricular septum
In which direction does the interventricular septum depolarize.
left-to-right
A tiny negative deflection in one or several left lateral leads is likely to reflect what event?
Septal depolarization
What is the normal maximum amplitude of septal Q waves?
0.1 mV
Normal vector range for ventricular depolarization.
0-90 degrees
What term describes an R-wave and an S-wave of nearly equal amplitude?
Biphasic QRS
The zone in which leads V3 and V4 are positioned, normally associated with biphasic waves.
Transition zone
What term describes the pattern of progressively increasing R-wave amplitude moving right to left across the precordial leads?
R-wave progression
True or False:
R-wave progression steadily increases from V1 to V6.
False:
The R-wave in V6 is usually a little smaller than that in V5.
The normal transition zone occurs in which leads?
V3 and V4
What is the duration of a normal QRS interval?
0.06 to 0.1 seconds
(2.5 small squares or
1/2 large square)
True or False:
The ST segment is usually downsloping in all leads.
False.
The ST segment is usually horizontal or gently upsloping in all leads.
The T-wave represents what cardiac event?
ventricular repolarization
True or False:
Repolarization requires more cellular energy than depolarization.
True.
Depolarization is largely passive; repolarization is an active product of the cell's membrane pump.
True or False:
The first cells to depolarize are also the first to repolarize in a healthy heart.
False.
Repolarization usually begins at the last area of the heart to have been depolarized and travels backward.
True or False:
It is typical and normal to find positive T-wave in the same leads that have tall R waves.
True
What is the amplitude or height of a normal T-wave?
one third to two thirds that of the corresponding R wave
True or False:
The duration of the QT interval is proportionate to the heart rate.
True.
The faster the heart rate, the shorter the QT interval.
What percentage of the normal cardiac cycle (R to R) does the QT interval generally compose?
40%
What is the orientation of V1 deflections in a normal EKG?
Predominantly Negative
What is the orientation of V6 deflections in a normal EKG?
Predominantly Positive
Mnemonic for the 11-step method for reading EKGs.
Slowly Read It, Always Read All, But Pray He Doesn't Crash!

Standardization
Rate
Intervals
Axis
Rhythm (4 questions)
AV Block
Bundle Branch Block
Preexitation
Hypertrophy
Disease (AMI)
Confusion (peculiarities)