Test Bank Guyton and Hall Textbook of Medical Physiology
14th Edition Hall | 9780323597128 | All Chapters with
Answers and Rationals
Electrocardiographic Interpretation of Cardiac Muscle and Coronary Blood Flow Abnormalities:
Vectorial Analysis
Most serious abnormalities of the heart muscle can be diagnosed by - ANSWER: Analyzing the
contours of the waves in the different electrocardiographic
An arrow that points in the direction of the electrical potential generated by the current flow, with
the arrowhead in the positive direction - ANSWER: Vector
The length of the vector arrow is drawn proportional to the - ANSWER: Voltage of the potential
The summated vector of the generated potential at this particular instant - ANSWER: Instantaneous
Mean Vector
When a vector is exactly horizontal and directed toward the person's left side, the vector is said to
extend in the direction of - ANSWER: 0 Degrees
From this zero reference point, the scale of vectors rotates - ANSWER: Clockwise
In a normal heart, the average direction of the vector during spread of the depolarization wave
through the ventricles, called the _________, is about +59 degrees - ANSWER: Mean QRS Vector
Mean QRS Vector - ANSWER: +59 Degrees
During most of the depolarization wave, the apex of the heart remains _______ with respect to the
base of the heart - ANSWER: Positive
the direction from negative electrode to positive electrode is called the _______ of the lead -
ANSWER: Axis
What is the axis for lead I? - ANSWER: 0 Degrees
What is the axis for lead II? - ANSWER: 60 Degrees
What is the axis for lead III? - ANSWER: 120 Degrees
What is the axis for the aVR lead? - ANSWER: 210 Degrees
What is the axis for the aVF lead? - ANSWER: 90 Degrees
What is the axis for the aVL - ANSWER: -30 Degrees
The combination of the three unipolar and three bipolar limb leads - ANSWER: Hexagonal Reference
System
When the vector in the heart is in a direction almost perpendicular to the axis of the lead, the voltage
recorded in the electrocardiogram of this lead is - ANSWER: Low
The potential in lead I is about ______ that of the actual potential in the heart - ANSWER: 1/2
, The potential in lead II is about ______ to that of the actual potential in the heart - ANSWER: Equal
The potential in lead III is about ______ that of the actual potential in the heart - ANSWER: 1/3
When the cardiac impulse enters the ventricles through the atrioventricular bundle, the first part of
the ventricles to become depolarized is the - ANSWER: Left Endocardial Surface Of The
Interventricular Septum
Initial depolarization of the heart causes the left endocardial surface of the interventricular septum to
be depolarized. The next area to be depolarized is the - ANSWER: Right Endocardial Surface Of The
Interventricular Septum
The ratio of the voltage in lead I to that in lead III ______ as the ventricles continue to depolarize -
ANSWER: Increases
the entire ventricular muscle mass is depolarized in approximately - ANSWER: 0.06 Seconds
The Q wave depression that can be seen sometimes at the start of the QRS depression is caused by
the ______ which creates a small vector with a negative ECG reading. - ANSWER: Depolarization Of
The Left Endocardial Surface First
The major positive deflection of the QRS complex of an ECG - ANSWER: R Wave
The major negative deflection of the QRS complex of an ECG - ANSWER: S Wave
After the ventricular muscle has become depolarized, about ___________ later, repolarization begins
- ANSWER: 0.15 Second
After the ventricular muscle has become depolarized, about 0.15 second later, repolarization begins
and proceeds until complete at about _________ - ANSWER: 0.35 Second
The greatest portion of ventricular muscle mass to repolarize first is the - ANSWER: Entire outer
surface of the ventricles, especially near the apex of the heart.
The endocardial areas are the _______ to repolarize - ANSWER: Last
Why do the endocardial surfaces repolarize after the outer surface of the heart? - ANSWER:
Postulated to be caused by the high blood pressure inside the ventricles during contraction, which
greatly reduces coronary blood flow to the endocardium, thereby slowing repolarization in the
endocardial areas
The T wave is generated over a period of time of a approximately - ANSWER: 0.15 Second
The point of original electronegativity in the atria is about at the point of entry of the - ANSWER:
Superior Vena Cava
Spread of depolarization through the atrial muscle is much slower than in the ventricles because the
atria have - ANSWER: No Purkinje system
the atrial repolarization vector is __________ to the vector of depolarization - ANSWER: Backward
Atrial T wave follows about ______ after the atrial P wave - ANSWER: 0.15 Second
depicts changes of the heart vectors at different times during the cardiac cycle - ANSWER:
Vectorcardiogram
This point is the negative end of all the successive vectors. - ANSWER: Zero Reference Point
14th Edition Hall | 9780323597128 | All Chapters with
Answers and Rationals
Electrocardiographic Interpretation of Cardiac Muscle and Coronary Blood Flow Abnormalities:
Vectorial Analysis
Most serious abnormalities of the heart muscle can be diagnosed by - ANSWER: Analyzing the
contours of the waves in the different electrocardiographic
An arrow that points in the direction of the electrical potential generated by the current flow, with
the arrowhead in the positive direction - ANSWER: Vector
The length of the vector arrow is drawn proportional to the - ANSWER: Voltage of the potential
The summated vector of the generated potential at this particular instant - ANSWER: Instantaneous
Mean Vector
When a vector is exactly horizontal and directed toward the person's left side, the vector is said to
extend in the direction of - ANSWER: 0 Degrees
From this zero reference point, the scale of vectors rotates - ANSWER: Clockwise
In a normal heart, the average direction of the vector during spread of the depolarization wave
through the ventricles, called the _________, is about +59 degrees - ANSWER: Mean QRS Vector
Mean QRS Vector - ANSWER: +59 Degrees
During most of the depolarization wave, the apex of the heart remains _______ with respect to the
base of the heart - ANSWER: Positive
the direction from negative electrode to positive electrode is called the _______ of the lead -
ANSWER: Axis
What is the axis for lead I? - ANSWER: 0 Degrees
What is the axis for lead II? - ANSWER: 60 Degrees
What is the axis for lead III? - ANSWER: 120 Degrees
What is the axis for the aVR lead? - ANSWER: 210 Degrees
What is the axis for the aVF lead? - ANSWER: 90 Degrees
What is the axis for the aVL - ANSWER: -30 Degrees
The combination of the three unipolar and three bipolar limb leads - ANSWER: Hexagonal Reference
System
When the vector in the heart is in a direction almost perpendicular to the axis of the lead, the voltage
recorded in the electrocardiogram of this lead is - ANSWER: Low
The potential in lead I is about ______ that of the actual potential in the heart - ANSWER: 1/2
, The potential in lead II is about ______ to that of the actual potential in the heart - ANSWER: Equal
The potential in lead III is about ______ that of the actual potential in the heart - ANSWER: 1/3
When the cardiac impulse enters the ventricles through the atrioventricular bundle, the first part of
the ventricles to become depolarized is the - ANSWER: Left Endocardial Surface Of The
Interventricular Septum
Initial depolarization of the heart causes the left endocardial surface of the interventricular septum to
be depolarized. The next area to be depolarized is the - ANSWER: Right Endocardial Surface Of The
Interventricular Septum
The ratio of the voltage in lead I to that in lead III ______ as the ventricles continue to depolarize -
ANSWER: Increases
the entire ventricular muscle mass is depolarized in approximately - ANSWER: 0.06 Seconds
The Q wave depression that can be seen sometimes at the start of the QRS depression is caused by
the ______ which creates a small vector with a negative ECG reading. - ANSWER: Depolarization Of
The Left Endocardial Surface First
The major positive deflection of the QRS complex of an ECG - ANSWER: R Wave
The major negative deflection of the QRS complex of an ECG - ANSWER: S Wave
After the ventricular muscle has become depolarized, about ___________ later, repolarization begins
- ANSWER: 0.15 Second
After the ventricular muscle has become depolarized, about 0.15 second later, repolarization begins
and proceeds until complete at about _________ - ANSWER: 0.35 Second
The greatest portion of ventricular muscle mass to repolarize first is the - ANSWER: Entire outer
surface of the ventricles, especially near the apex of the heart.
The endocardial areas are the _______ to repolarize - ANSWER: Last
Why do the endocardial surfaces repolarize after the outer surface of the heart? - ANSWER:
Postulated to be caused by the high blood pressure inside the ventricles during contraction, which
greatly reduces coronary blood flow to the endocardium, thereby slowing repolarization in the
endocardial areas
The T wave is generated over a period of time of a approximately - ANSWER: 0.15 Second
The point of original electronegativity in the atria is about at the point of entry of the - ANSWER:
Superior Vena Cava
Spread of depolarization through the atrial muscle is much slower than in the ventricles because the
atria have - ANSWER: No Purkinje system
the atrial repolarization vector is __________ to the vector of depolarization - ANSWER: Backward
Atrial T wave follows about ______ after the atrial P wave - ANSWER: 0.15 Second
depicts changes of the heart vectors at different times during the cardiac cycle - ANSWER:
Vectorcardiogram
This point is the negative end of all the successive vectors. - ANSWER: Zero Reference Point
