BCIT - TEST 1 - ECG / PACEMAKERS - CARD 3330
UPDATED ACTUAL QUESTIONS AND CORRECT
ANSWERS
Question:
1. phases of action potential
Answer:
1 - resting state - -90mv - Sodium out, potassium in.
2 - depolarization phase - +20mv sodium in, potassium out
3 - repolarization phase - Close sodium channels, loss of potassium, calcium
channels open. Calcium flows out too.
4 - hyperpolarization/terminal - calcium out, potassium in, sodium out.
Question:
2. cardiac conduction system
Answer:
a system of specialized muscle tissues which conduct electrical impulses that
stimulate the heart to beat.
the sinoatrial node (SA node), internodal tracts, atrioventricular node (AV node),
bundle of His, right and left bundle branches, and the Purkinje fibres
Question:
3. Cardiac cells can be divided into two basic types
Answer:
conduction and contraction
Question:
4. cellular properties
Answer:
excitability, automaticity, conductivity, contractility, and refractoriness
Question:
5. Excitability
Answer:
the ability of a cell to respond to a given electrical stimulus when it is not in a state
of refractoriness
,Question:
6. Automaticity
Answer:
the ability of the cell to spontaneously initiate an action potential. (commonly SA
node)
Question:
7. Conductivity
Answer:
the ability of a cardiac cell to transmit an electrical impulse to another cell. (Gap
junctions)
Question:
8. Refractoriness
Answer:
the cell's inability to be re-stimulated after depolarization. This is a preventive
mechanism that allows the cell time to contract.
Question:
9. sinoatrial cells
Answer:
P - pacemaker calls
T - Transitional cells
Question:
10. Norepinephrine (NE)
Answer:
the neurotransmitter used by the sympathetic division of the autonomic nervous
system at the post-ganglionic organ-level (synapse).
innervates both the atria and ventricles. It governs increases in heart rate and AV
conduction. It is also responsible for the "irritability" of cardiac cells.
Question:
11. SA node receives blood from:
Answer:
SA nodal artery, 2/3 of pop originates in first branch or right coronary artery.
Question:
12. AV nodal delay
Answer:
The unique crisscross matrix of the AV node provides the necessary delay in
impulse conduction so that atrial contraction can precede ventricular contraction.
, Question:
13. Starling's law of the heart
Answer:
the greater the ventricles stretch, enlarging their volume, the more blood will be
pumped out.
Question:
14. AV node may assume the role of pacemaker.
Answer:
If the SA node is diseased or impaired. Beats around 40 to 60 beats per minute
(bpm). The resulting rhythm is considered a nodal or junctional rhythm.
Question:
15. Hemiblocks
Answer:
Involve conduction failure in one of the divisions of the left bundle branch (
anterior or posterior)
Anterior block: affects the superior portion of the ventricle
Posterior: affects the inferior portion
Question:
16. Left Anterior Fascicular Block (LAFB)
Answer:
This presents with an unexplained left-axis deviation
Left axis deviation, usually >-60 degrees
Small Q in leads I and aVL, small R in II, III and AVF
Usually normal QRS duration
Late intrinsicoid deflection in a VL (>0.045 secs)
Increased QRS voltage in limb leads
Question:
17. Left Posterior Fascicular Block (LPFB)
Answer:
This presents with an unexplained right-axis deviation
Right axis deviation (usually > +120 degrees)
Small R in leads I and AVL, small Q in II, III and aVF
Usually normal QRS duration
Late intrinsicoid deflection in aVF (>0.045 secs)
No evidence for right ventricular hypertrophy
UPDATED ACTUAL QUESTIONS AND CORRECT
ANSWERS
Question:
1. phases of action potential
Answer:
1 - resting state - -90mv - Sodium out, potassium in.
2 - depolarization phase - +20mv sodium in, potassium out
3 - repolarization phase - Close sodium channels, loss of potassium, calcium
channels open. Calcium flows out too.
4 - hyperpolarization/terminal - calcium out, potassium in, sodium out.
Question:
2. cardiac conduction system
Answer:
a system of specialized muscle tissues which conduct electrical impulses that
stimulate the heart to beat.
the sinoatrial node (SA node), internodal tracts, atrioventricular node (AV node),
bundle of His, right and left bundle branches, and the Purkinje fibres
Question:
3. Cardiac cells can be divided into two basic types
Answer:
conduction and contraction
Question:
4. cellular properties
Answer:
excitability, automaticity, conductivity, contractility, and refractoriness
Question:
5. Excitability
Answer:
the ability of a cell to respond to a given electrical stimulus when it is not in a state
of refractoriness
,Question:
6. Automaticity
Answer:
the ability of the cell to spontaneously initiate an action potential. (commonly SA
node)
Question:
7. Conductivity
Answer:
the ability of a cardiac cell to transmit an electrical impulse to another cell. (Gap
junctions)
Question:
8. Refractoriness
Answer:
the cell's inability to be re-stimulated after depolarization. This is a preventive
mechanism that allows the cell time to contract.
Question:
9. sinoatrial cells
Answer:
P - pacemaker calls
T - Transitional cells
Question:
10. Norepinephrine (NE)
Answer:
the neurotransmitter used by the sympathetic division of the autonomic nervous
system at the post-ganglionic organ-level (synapse).
innervates both the atria and ventricles. It governs increases in heart rate and AV
conduction. It is also responsible for the "irritability" of cardiac cells.
Question:
11. SA node receives blood from:
Answer:
SA nodal artery, 2/3 of pop originates in first branch or right coronary artery.
Question:
12. AV nodal delay
Answer:
The unique crisscross matrix of the AV node provides the necessary delay in
impulse conduction so that atrial contraction can precede ventricular contraction.
, Question:
13. Starling's law of the heart
Answer:
the greater the ventricles stretch, enlarging their volume, the more blood will be
pumped out.
Question:
14. AV node may assume the role of pacemaker.
Answer:
If the SA node is diseased or impaired. Beats around 40 to 60 beats per minute
(bpm). The resulting rhythm is considered a nodal or junctional rhythm.
Question:
15. Hemiblocks
Answer:
Involve conduction failure in one of the divisions of the left bundle branch (
anterior or posterior)
Anterior block: affects the superior portion of the ventricle
Posterior: affects the inferior portion
Question:
16. Left Anterior Fascicular Block (LAFB)
Answer:
This presents with an unexplained left-axis deviation
Left axis deviation, usually >-60 degrees
Small Q in leads I and aVL, small R in II, III and AVF
Usually normal QRS duration
Late intrinsicoid deflection in a VL (>0.045 secs)
Increased QRS voltage in limb leads
Question:
17. Left Posterior Fascicular Block (LPFB)
Answer:
This presents with an unexplained right-axis deviation
Right axis deviation (usually > +120 degrees)
Small R in leads I and AVL, small Q in II, III and aVF
Usually normal QRS duration
Late intrinsicoid deflection in aVF (>0.045 secs)
No evidence for right ventricular hypertrophy
