UCLA EKG TEST/ EKG TEST UCLA QUESTIONS
& ANSWERS
Electrically polarized at rest - ANSWER-- 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 - ANSWER-difference between the charges outside and inside
of the cell wall
Depolarization - ANSWER-NA moves into the cell rapidly in response to an
electrical impulse
- inside cell loses negative potential
Repolarization - ANSWER-ions return to their original resting state
- heart cells restore their resting polarity
4 Phases of Electrophysiology of the heart cell - ANSWER-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 - ANSWER-- Sinoatrial node (SA) node
-Atrioventricular node) AV node
- Purkinje fibers
SA node - ANSWER--primary pacemaker
- Rate: 60-100
- SA node depolarizes the atria via intro nodal tracts and Bachmann’s bundle =
resulting in atrial contraction
AV node - ANSWER-- responsible for slowing down conduction from the atria to
ventricles just long enough for atrial contraction to occur - rate: 40-60
, Bundle of His - ANSWER-- divides left and right branches
-impulses are conducted down LBB faster than RBB, allowing both ventricles to
contract at same time
Purkunje fibers - ANSWER-- send impulses into my cardinal tissues of the
ventricles and causes them to contract
- rate: 20-40
Myocardial cells - ANSWER--contractile machinery of the heart
myocardial cell is depolarized, CA is released within cell causing cell to contract
Normal ranges for electrolytes - ANSWER-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 - ANSWER-v1: right sternal boarder and 4th
intercostal space
V2: left sternal boarder and 4th intercostal space
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 - ANSWER-- small box: 0.04 secs
- 5 small box: 0.2 secs
- 5 Large box= 1 second
- 300 large boxes = 60 secs
PR interval - ANSWER-0.12- 0.20 secs
- beginning of the P wave to beginning of the QRS
QRS complex interval/ duration - ANSWER-- 0.04- 0.12 secs
- ventricular depolarization
& ANSWERS
Electrically polarized at rest - ANSWER-- 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 - ANSWER-difference between the charges outside and inside
of the cell wall
Depolarization - ANSWER-NA moves into the cell rapidly in response to an
electrical impulse
- inside cell loses negative potential
Repolarization - ANSWER-ions return to their original resting state
- heart cells restore their resting polarity
4 Phases of Electrophysiology of the heart cell - ANSWER-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 - ANSWER-- Sinoatrial node (SA) node
-Atrioventricular node) AV node
- Purkinje fibers
SA node - ANSWER--primary pacemaker
- Rate: 60-100
- SA node depolarizes the atria via intro nodal tracts and Bachmann’s bundle =
resulting in atrial contraction
AV node - ANSWER-- responsible for slowing down conduction from the atria to
ventricles just long enough for atrial contraction to occur - rate: 40-60
, Bundle of His - ANSWER-- divides left and right branches
-impulses are conducted down LBB faster than RBB, allowing both ventricles to
contract at same time
Purkunje fibers - ANSWER-- send impulses into my cardinal tissues of the
ventricles and causes them to contract
- rate: 20-40
Myocardial cells - ANSWER--contractile machinery of the heart
myocardial cell is depolarized, CA is released within cell causing cell to contract
Normal ranges for electrolytes - ANSWER-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 - ANSWER-v1: right sternal boarder and 4th
intercostal space
V2: left sternal boarder and 4th intercostal space
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 - ANSWER-- small box: 0.04 secs
- 5 small box: 0.2 secs
- 5 Large box= 1 second
- 300 large boxes = 60 secs
PR interval - ANSWER-0.12- 0.20 secs
- beginning of the P wave to beginning of the QRS
QRS complex interval/ duration - ANSWER-- 0.04- 0.12 secs
- ventricular depolarization
