Atrial Fibrillation Pathophysiology || 100% Accurate Solutions.
The electrical signal starts in _____________ correct answers Sinoatrial (SA) node
How does electrical signal start in the sinoatrial node? correct answers Because of automaticity
(spontaneous impulse generation)
Note: this is affected by autonomic nervous system (cholinergic and sympathetic)
True or false: only the sinoatrial node has automatic properties correct answers False, other parts
of the conduction system also have inherent automatic properties. However, their rate is less than
SA node. Thus, the SA "dominates" over the other parts downstream.
After starting in the SA node, where the the electrical signal move to? correct answers To the
atrioventricular node through an atrial specialized conducting system
Note" the AV node is the "only conducting" port of the ventricles
After the electrical signal moves through the atrioventricular node, where does it go? correct
answers It moves through the bundle of His and Purkinje fibers to the final filaments until it
reaches all myocytes in the ventricles
Where does Bachman's bundle take the electrical signal to? correct answers The right atrium
Where does the Bundle of Kent take the electrical signal to? correct answers From the atrium to
the ventricular, either on left or right side (but it is an ACCESSORY bundle, it is not normal for
it to exist - it can cause Wolff-Parkinson-White Syndrome)
Note: normally, the only electrical connection between the atria and ventricles is the AV node,
which can delay the electrical current. Bundle of Kent is secret backdoor entrance.
In the ECG, what symbolizes atria depolarization? correct answers P wave
On an ECG, what symbolizes ventricular depolarization? correct answers QRS
On an ECG, what symbolizes ventricular repolarization? correct answers ST wave
In the action potential, what happens in phase 0? correct answers Depolarization.
Na+ entry through Na+ channels.
In the LV, phase 0 of the action potential will show up as what on the ECG? correct answers
Beginning of QRS complex
In the action potential, what happen at phase 1? correct answers Overshoot phase.
Calcium enters the cell and contracting starts.
, In the LV, phase 1 of the action potential shows up as what on the ECG? correct answers QRS
complex (calcium enters the cell and ventricular contraction begins)
In the action potential, what happens during phase 2? correct answers Plateau phase.
Inward slow Na+ and Ca2+, and outward K+.
In the action potential, what happens during phase 3? correct answers Calcium channels
inactivate and outward K+ continues.
In the LV, phase 3 of the action potential shows up as what on the ECG? correct answers ST
wave (ventricular repolarization)
What happens during phase 4 of the action potential? correct answers Resting phase.
Outward Na+ and inward K+ through active pumping.
Action potential duration is measured from phase ____ to the end of phase ____ correct answers
0
3
What is the effective refractory period? correct answers The time where the cell is refractory and
will not propagate any further impulse
When a patient has a 12 lead ECG, where are the electrodes placed? correct answers Left hand,
right hand, left foot, 6 on the chest.
Note: there is also one on the right foot, but that is only used for electrical grounding.
How many "views" of the heart do EKG limb leads have? correct answers 6 views: I, II, III, aVF,
aVL, and aVR
Note: aV stands for "augmented voltage"
Where do leads I, II, and III look at the heart from? correct answers I: lateral left side
II: inferior left side
III: inferior right side
On EKG paper, a small square is ____mm and represents _____ seconds correct answers 1mm
0.04 seconds
On EKG paper, a large square is ___mm and represents ____ seconds correct answers 5mm
0.20 seconds
____ large squares on an EKG represent 1 second correct answers 5
_____ large squares on an EKG represent 6 seconds correct answers 30
The electrical signal starts in _____________ correct answers Sinoatrial (SA) node
How does electrical signal start in the sinoatrial node? correct answers Because of automaticity
(spontaneous impulse generation)
Note: this is affected by autonomic nervous system (cholinergic and sympathetic)
True or false: only the sinoatrial node has automatic properties correct answers False, other parts
of the conduction system also have inherent automatic properties. However, their rate is less than
SA node. Thus, the SA "dominates" over the other parts downstream.
After starting in the SA node, where the the electrical signal move to? correct answers To the
atrioventricular node through an atrial specialized conducting system
Note" the AV node is the "only conducting" port of the ventricles
After the electrical signal moves through the atrioventricular node, where does it go? correct
answers It moves through the bundle of His and Purkinje fibers to the final filaments until it
reaches all myocytes in the ventricles
Where does Bachman's bundle take the electrical signal to? correct answers The right atrium
Where does the Bundle of Kent take the electrical signal to? correct answers From the atrium to
the ventricular, either on left or right side (but it is an ACCESSORY bundle, it is not normal for
it to exist - it can cause Wolff-Parkinson-White Syndrome)
Note: normally, the only electrical connection between the atria and ventricles is the AV node,
which can delay the electrical current. Bundle of Kent is secret backdoor entrance.
In the ECG, what symbolizes atria depolarization? correct answers P wave
On an ECG, what symbolizes ventricular depolarization? correct answers QRS
On an ECG, what symbolizes ventricular repolarization? correct answers ST wave
In the action potential, what happens in phase 0? correct answers Depolarization.
Na+ entry through Na+ channels.
In the LV, phase 0 of the action potential will show up as what on the ECG? correct answers
Beginning of QRS complex
In the action potential, what happen at phase 1? correct answers Overshoot phase.
Calcium enters the cell and contracting starts.
, In the LV, phase 1 of the action potential shows up as what on the ECG? correct answers QRS
complex (calcium enters the cell and ventricular contraction begins)
In the action potential, what happens during phase 2? correct answers Plateau phase.
Inward slow Na+ and Ca2+, and outward K+.
In the action potential, what happens during phase 3? correct answers Calcium channels
inactivate and outward K+ continues.
In the LV, phase 3 of the action potential shows up as what on the ECG? correct answers ST
wave (ventricular repolarization)
What happens during phase 4 of the action potential? correct answers Resting phase.
Outward Na+ and inward K+ through active pumping.
Action potential duration is measured from phase ____ to the end of phase ____ correct answers
0
3
What is the effective refractory period? correct answers The time where the cell is refractory and
will not propagate any further impulse
When a patient has a 12 lead ECG, where are the electrodes placed? correct answers Left hand,
right hand, left foot, 6 on the chest.
Note: there is also one on the right foot, but that is only used for electrical grounding.
How many "views" of the heart do EKG limb leads have? correct answers 6 views: I, II, III, aVF,
aVL, and aVR
Note: aV stands for "augmented voltage"
Where do leads I, II, and III look at the heart from? correct answers I: lateral left side
II: inferior left side
III: inferior right side
On EKG paper, a small square is ____mm and represents _____ seconds correct answers 1mm
0.04 seconds
On EKG paper, a large square is ___mm and represents ____ seconds correct answers 5mm
0.20 seconds
____ large squares on an EKG represent 1 second correct answers 5
_____ large squares on an EKG represent 6 seconds correct answers 30
