Discussion

Question 1

____________ refers to the spontaneous time-dependent depolarization of the cell membrane that leads to an action potential in an otherwise quiescent cell.

Answer 1

Pacemaker activity

Question 2

SA node intrinsic firing rate:

Answer 2

70-80

Question 3

Primary pacemaker

Answer 3

SA node

Question 4

Beta adrenergic effect (e.g epinephrine) to SA Node:

Answer 4

Increase conduction velocity

Increase pacemaker rate

Question 5

1st Sequence of depolarization in cardiac muscle:

Answer 5

Depolarize atria

Question 6

2nd Sequence of depolarization in cardiac muscle

Answer 6

Depolarize septum from left to right

Question 7

Third Sequence of depolarization in cardiac muscle

Answer 7

Depolarize anteroseptal region of myocardium toward the apex

Question 8

Fourth Sequence of depolarization in cardiac muscle:

Answer 8

Depolarize bulk of ventricular myocardium from endocardium to epicardium

Question 9

1st electrical events of cardiac cycle:

Answer 9

Atrial depolarization initatiated by the SA node, causes the P wave

Question 10

Second electrical events of cardiac cycle:

Answer 10

With atrial depolarization complete, the impulse is delayed at the AV node.

Question 11

Limb leads:

Answer 11

I, II, III, aVL, aVR, aVF

Question 12

Chest leads

Answer 12

V1, V2, V3, V4, V5, V6

Question 13

4th intercostal space at the right sternal border

Answer 13

V1 or C1 (Red)

Question 14

4th intercostal space at the left sternal border

Answer 14

V2 (C2) Yellow

Question 15

On the left on the 5th rib between C2 and C4

Answer 15

V3 C3 Green

Question 16

5th intercostal space on the left midclavicular line

Answer 16

V4 C4 Brown

Question 17

PR interval

Answer 17

0.12 - 0.22 secs

Question 18

The usual paper speed is

Answer 18

25 mm/sec

Question 19

1 mm (small square)

Answer 19

0.04 sec

Question 20

5 mm (big square)

Answer 20

0.2 sec

Question 21

P-waves should precede every QRS complex and the P-wave should be positive in Lead II

Answer 21

Rhythm

Question 22

The most efficient way to estimate axis is to look at ______ and _______.

Answer 22

Lead I and Lead AVF

Question 23

Generated by activation of the atria

Answer 23

P wave

Question 24

Represents the duration of atrioventricular (AV) conduction

Answer 24

PR segment

Question 25

Produced by activation of both ventricles

Answer 25

QRS complex

Question 26

Reflects ventricular recovery

Answer 26

ST-T wave

Question 27

Lead I is formed using the _______ as the negative electrode and the _________ electrode as the positive.

Answer 27

Right arm

Left arm

Question 28

Lead II is formed using the ________ as the negative electrode and the __________ electrode as the positive.

Answer 28

Right arm

Left LEG

Question 29

Lead III is formed using the _______ as the negative electrode and the ________ electrode as the positive.

Answer 29

Left arm

Left leg

Question 30

aVL, aVF and aVR are _________ computed using the information from the other leads.

Answer 30

Composite leads

Question 31

Limb leads look at the heart in the __________/

Answer 31

Coronal plane

Question 32

Phase 2 of transmembrane potential

Answer 32

ST-segment

Question 33

Isoelectric in normal subjects

Answer 33

ST-segment

Question 34

reflects the duration of depolarization and repolarization

Answer 34

QT interval

Question 35

Surface reflection of negative after potential

Answer 35

U wave

Question 36

Repolarization of purkinje fibers and ventricular relaxation

Answer 36

U wave