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UCLA EKG test Questions and Correct
Answers
electrically polarized at rest Ans: - inside of heart cell has
a high potassium concentration, whereas the outside has a
higher concentration of NA
-higher positive charge outside the cell cause more negative
charge inside cell
electrical potential Ans: difference between the charges
outside and inside of the cell wall
Depolarization Ans: NA moves into the cell rapidly in
response to an electrical impulse
- inside cell loses negative potential
Replolarization Ans: ions return to their original resting
state
- heart cells restore their resting polarity
4 Phases of Electrophysiology of the heart cell Ans: Phase
0: Na flow in and rapid depolarization occurs when
stimulated
Phase 1: Rapid return to isoelectric level
Phase 2: CA ions flow in and myocytes contract
Phase 3: K flow out and rapid depolarization occurs
Phase 4: Polarized resting phase
Pacemaker cells Ans: - Sinoatrial node ( SA) node
-Atrioventricular node )AV node
- Purkinjie fibers
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SA node Ans: -primary pacemaker
- Rate: 60-100
- SA node depolarizes the atria via intro nodal tracts and
Bachmann;s bundle = resulting in atrial contraction
AV node Ans: - responsible for slowing down conduction
from the atria to ventricles just long enough for atrial
contraction to occur
- rate: 40-60
Bundle of His Ans: - divides left and right branches
-impulses are conducted down LBB faster than RBB,
allowing both ventricles to contract at same time
Purkunje fibers Ans: - send impulses into mycardial tissues
of the ventricles and causes them to contract
- rate: 20-40
Myocardial cells Ans: -contractile machinery of the heart
- myocardial cell is deplolarized, CA is released within cell
causing cell to contract
Normal ranges for electrolytes Ans: NA: 135- 146 meq/L
K: 3.6-5.3 meq/L
Ca: 8.5- 10.3 mg/dl
Ionized Ca: 1.09 -1.29
Mg: 1.4- 1.9 mEq/L
Placement of precordial leads Ans: v1: right sternal boarder
and 4th intercostal space
v2: left sternal boarder and 4th intercostal space
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v3: between v2 and v4
v4: midclavicular line and 5th intercostal space
v5: between v4 and v6
v6: between midaxillary line and 5th intercostal space
EKG paper Ans: - small box: 0.04 secs
- 5 small box: 0.2 secs
- 5 Large box= 1 second
- 300 large boxes = 60 secs
PR interval Ans: 0.12- 0.20 secs
- beginning of the P wave to beginning of the QRS
QRS complex interval/ duration Ans: - 0.04- 0.12 secs
- ventricular deplolarization
U wave Ans: - small low amplitude that follows T wave
- indicative of hypokalemia
QT interval Ans: 0.36- 0.44 secs
- measures beginning of ventricular replarization to end of
reploarization
medications that prolong QT interval Ans: - amiodarone
-sotalol
-levofloxacin
-zofran
-celexa
-haloperidol
© 2025 All rights reserved
UCLA EKG test Questions and Correct
Answers
electrically polarized at rest Ans: - inside of heart cell has
a high potassium concentration, whereas the outside has a
higher concentration of NA
-higher positive charge outside the cell cause more negative
charge inside cell
electrical potential Ans: difference between the charges
outside and inside of the cell wall
Depolarization Ans: NA moves into the cell rapidly in
response to an electrical impulse
- inside cell loses negative potential
Replolarization Ans: ions return to their original resting
state
- heart cells restore their resting polarity
4 Phases of Electrophysiology of the heart cell Ans: Phase
0: Na flow in and rapid depolarization occurs when
stimulated
Phase 1: Rapid return to isoelectric level
Phase 2: CA ions flow in and myocytes contract
Phase 3: K flow out and rapid depolarization occurs
Phase 4: Polarized resting phase
Pacemaker cells Ans: - Sinoatrial node ( SA) node
-Atrioventricular node )AV node
- Purkinjie fibers
© 2025 All rights reserved
, 2 | Page
SA node Ans: -primary pacemaker
- Rate: 60-100
- SA node depolarizes the atria via intro nodal tracts and
Bachmann;s bundle = resulting in atrial contraction
AV node Ans: - responsible for slowing down conduction
from the atria to ventricles just long enough for atrial
contraction to occur
- rate: 40-60
Bundle of His Ans: - divides left and right branches
-impulses are conducted down LBB faster than RBB,
allowing both ventricles to contract at same time
Purkunje fibers Ans: - send impulses into mycardial tissues
of the ventricles and causes them to contract
- rate: 20-40
Myocardial cells Ans: -contractile machinery of the heart
- myocardial cell is deplolarized, CA is released within cell
causing cell to contract
Normal ranges for electrolytes Ans: NA: 135- 146 meq/L
K: 3.6-5.3 meq/L
Ca: 8.5- 10.3 mg/dl
Ionized Ca: 1.09 -1.29
Mg: 1.4- 1.9 mEq/L
Placement of precordial leads Ans: v1: right sternal boarder
and 4th intercostal space
v2: left sternal boarder and 4th intercostal space
© 2025 All rights reserved
, 3 | Page
v3: between v2 and v4
v4: midclavicular line and 5th intercostal space
v5: between v4 and v6
v6: between midaxillary line and 5th intercostal space
EKG paper Ans: - small box: 0.04 secs
- 5 small box: 0.2 secs
- 5 Large box= 1 second
- 300 large boxes = 60 secs
PR interval Ans: 0.12- 0.20 secs
- beginning of the P wave to beginning of the QRS
QRS complex interval/ duration Ans: - 0.04- 0.12 secs
- ventricular deplolarization
U wave Ans: - small low amplitude that follows T wave
- indicative of hypokalemia
QT interval Ans: 0.36- 0.44 secs
- measures beginning of ventricular replarization to end of
reploarization
medications that prolong QT interval Ans: - amiodarone
-sotalol
-levofloxacin
-zofran
-celexa
-haloperidol
© 2025 All rights reserved
