EKG: Chapter 2 Electrophysiology
One small block on the EKG paper measures ______ seconds
0.04
Normal QRS interval in ______ seconds or less than three small blocks
0.12
On EKG paper, one big block represents
0.20 seconds
The ventricles inherent rate is
20-40
If the sinus node, atria, and AV node all fail, the heart rate will be between
20-40 bpm
The PR INTERVAL would be considered abnormal if it measured _______ small blocks on the EKG paper
6
The normal inherent rate of the sinus node as a pacemaker is
60-100 bpm
The PR interval measures the time it takes for the impulse to travel from the
Atria to the Ventricle
What electrical event must occur for atrial contraction to occur?
Atrial depolarization
Which of the following ions has a direct effect on ventricular muscle contraction?
Calcium
Which of the following is NOT true?
Cardiac cells can contract without having been depolarized.
Which of the following characteristics of heart cells is mechanical
Contractility
Depolarization is a(n)
Electrical event that should result in muscle contraction
During the absolute refractory period, only a strong stimulus can result in depolarization (t/f)
False
The cardiac cell, at rest, has a transmembrane potential of +20mV (t/f)
False
After the sinus node initiates an impulse, where does the impulse go next?
Interatrial tracts
What is TRUE about the following intervals: PR 0.14 QRS 0.08
Intervals are normal
Which of the following correctly describes the relative refractory period?
It is the period in which only a strong impulse can cause another depolarization
Which of these statements about the sinus node is FALSE
It is the slowest pacemaker of the heart
Atrial depolarization is represented on the EKG is a _____
P wave
If the sinus node and atria both fail, the ______ will be absent on the rhythm strip
P wave
The PR segment is located between the
P wave and QRS complex
The baseline on the EKG strip is considered to be the
PR segment
A negative deflection that occurs before a positive one is labeled is a _____ wave
Q
The ST segment is located between the
QRS complex and the T wave
Phase 0 of the action potential corresponds with what wave or complex on the EKG
QRS complex?
An upward deflection is called a(n)
R wave
A QRS complex with one positive deflection followed by one negative deflection would be labeled
RS
Normal conduction begins with the pacemaker of the heart is the
SA node
The wave or complex that represents ventricular repolarization is the
T wave
The P wave represents atrial depolarization (t/f)
True
The baseline is a flat line from which the waves and complexes take off (t/f)
True
The normal rate of the sinus node is 60-100 bpm (t/f)
True
The polarized cardiac cell is electrically negative (t/f)
True
Arrhythmias are _______ heart rhythms
abnormal
If a heart rhythm is slower than normal it is called a(n)
arrhythmia
The P wave represents
atrial depolarization
The pacemaker is the ______ of the conduction system of the heart
beginning
Transmembrane potential is the electrical charge at the ______
cell membrane
Contractility is the ability of a cardiac cell to
contract
In the action potential, phase 0 is
depolarization
A beat that appears on the rhythm strip after a long pause and causes a slower rhythm is called a(n)
escape beat
Cardiac cell stimulus during the absolute refractory period often results in very fast, dangerous rhythms.(t/f)
false
The PR segment is a flat line located between the QRS complex and T wave (t/f)
false
The ST segment is a flat line from which the waves and complexes take off (t/f)
false
The normal pacemaker of the heart is the AV node (t/f)
false
The EKG is the recording of the
heart's electrical activity
The term "repolarization" refers to?
heart's electrical activity
The electrical impulse travels through the _____ to get from the atrium to the AV node
internodal tracts
The normal ST segment is
isoelectric line
The cardiac cell at rest has what kind of electrical charge?
negative charge
Depolarization is the changing of the cardiac cell is to an electrically ______ charge
neutral
The area of the conduction system that initiates the impulse is called the
pacemaker
The job of the cardiac conduction system's pacemaker is to
propagate electrical impulses, conduct electrical impulses, and cause depolarization of the myocardial cells
In the action potential, phase 3 is
rapid repolarization
Refractory means to______
resist
The normal pacemaker of the heart is the
sinus node
On a rhythm strip, the P wave is normally
small
+20 mV
transmembrane potential at the conclusion of phase 0 of the action potential
If the PR interval is 0.10 seconds, the time it takes for the impulse to travel from the atrium down to the ventricle is abnormal (t/f)
true
The PR interval measures the time it takes for the impulse to travel from the atrium down to the ventricle (t/f)
true
A QRS complex that has both an R and R' wave will have
two positive deflections
The relative refractory period extends from the
upstroke of the T wave to the end of the T wave
If a pacemaker becomes irritable and fires at a faster than normal rate, _______ will occur
usurpation
The pacemaker with the slowest inherent rate is the ______
ventricle
The QRS complex represents
ventricular depolarization
The T wave represents
ventricular repolarization