(2) Physiologic Basis for ECG and Basic ECG (Ballam) Flashcards
How many electrodes to you place on the skin surface for an EKG?
12 Electrodes
What exactly does an EKG measure?
EXTRAcellular potential
Describe:
EKG Tracing Deflection
(A) Depolarization starts, observe upward deflection
(B) All cells depolarized, NO DIFFERENCE
(C) Repolarizatio starts, observe downward deflection
(D) Once all cells are repolarized, NO DIFFERENCE
Identify the regions for depolarization of the:
(A) Atria
(B) Ventricles
What is occuring during the P wave?
SA nodes cause atria to depolarize from right to left
What occurs during QRS complex?
Ventricles depolarize
(from right to left, interior to exterior)
What occurs during ST segment?
Action potential phase 2 delays repolarization of ventricles
What occurs during the T wave?
Ventricles repolarize
(left to right)
What phase does the p wave represent in an atrial muscle AP?
Phase 0
What phase does the QRS complex represent in ventricular muscle?
Phase 0 of AP in ventricular muscle
Significance of the U Wave?
Not typically observed
Suspected to be related to unknown pathologies
Draw:
1) An atrial AP in comparison to a ventricular AP on the same time axis
2) Atrial contraction and ventricular contraction on same time axis
3) All compared to a normal EKG rhythm
What does a segment represent?
Duration of a single event on EKG
What does an interval represent?
Duration of two or more events on EKG
What does one heavy lined box represent VERTICALLY?
0.5 mV
What does one heavy lined box represent HORIZONTALLY?
0.2 seconds
Calculate the
A) times between beats
B) beats per min
Time between beats (5 x 0.2) + (2 x 0.04) = 1.08 sec
(60 sec/min) / 1.08 seconds = 55 beats / min
Which chest leads are primarily negative?
V1 and V2
Which chest lead typically demonstrates the “best” EKG?
V3
Which chest leads are primarily positive?
V4, V5 and V6
Describe where you would place chest leads:
