Review of ECG

Question 1

what channel contributes to the diastolic depolarization?

Answer 1

funny channel

Question 2

which channel is slow, depolarizing?

Answer 2

calcium

Question 3

which channel is rapid, depolarizing?

Answer 3

sodium

Question 4

which channel is responsible for repolarization?

Answer 4

potassium

Question 5

what is the role of the funny channel? when is it closed?

Answer 5

allows positive charge to enter cell during repolarization / hyperpolarization

depolarization

Question 6

what is the theme of phase 1 of cardiac AP?

Answer 6

early repolarization

Question 7

what occurs during phase 1 of cardiac AP?

Answer 7

sodium channels close
some potassium channels open
repolarization incomplete

Question 8

phase 2 of cardiac AP is due to what ion?

Answer 8

calcium

Question 9

what is the membrane potential of cardiac AP phase 2?

Answer 9

approx zero

Question 10

what occurs during phase 0 of cardiac AP? which ion / channel is responsible?

Answer 10

depolarization

fast sodium channels

Question 11

what is the theme of phase 2 of cardiac AP?

Answer 11

plateau

Question 12

what is the theme of phase 3 of cardiac AP?

Answer 12

rapid repolarization

Question 13

what is occuring during phase 3 of the cardiac AP?

Answer 13

more calcium channels are closing 
opening of (more) potassium channels

Question 14

what is the theme of phase 4 of the cardiac AP?

Answer 14

resting membrane potential

Question 15

what is occurring during phase 4 of the cardiac AP? which channels are open?

Answer 15

resting potential maintained until next stimulus

only potassium channels are open

Question 16

which phases are lacking in the nodal AP?

Answer 16

1 and 2

Question 17

which channels open once threshold is reached in nodal AP?

Answer 17

calcium

Question 18

during nodal AP, when do calcium channels open?

Answer 18

upon reaching threshold

Question 19

are there fast sodium channels in nodal AP?

Answer 19

no

Question 20

what occurs after max depolarization in nodal AP? which phase is this?

Answer 20

depolarizatino - potassium channels open

phase 3

Question 21

what is the funny current in nodal AP? what is the result?

Answer 21

progressive reduction in potassium efflux
progressive increase in calcium influx

slowly depolarizes cell

Question 22

what is the normal sequence of depolarization?

Answer 22

SA 
atria 
AV 
His 
bundle branches 
purkinje 
ventricles (septum - apex - ventricular free walls)

Question 23

why does signal slow down at the AV node?

Answer 23

differences in connections between these cells - fewer cells

Question 24

which part of the ventricles depolarize first?

Answer 24

septum

Question 25

what are the bipolar limb leads?

Answer 25

I, II, III

Question 26

what are the augmented unipolar limb leads?

Answer 26

aVR, aVL, aVF

Question 27

what are the horizontal transverse plane chest leads?

Answer 27

V1 - V6

Question 28

where is V1 located?

Answer 28

4th intercostal space, R sternal border

Question 29

where is V2 located?

Answer 29

4th intercostal space, L sternal border

Question 30

where is V4 located?

Answer 30

5th intercostal space, midclavicular line

Question 31

where is V3 located?

Answer 31

between V2 and V4

Question 32

where is V5 located?

Answer 32

in line with V4, anterior axillary line

Question 33

where is V6 located?

Answer 33

in line with V4 and V5, midaxillary line (down from armpit)

Question 34

what does the ST segment correspond to on the ECG?

Answer 34

phase 2 plateau

Question 35

what does the QT segment correspond to on the ECG?

Answer 35

ventricular depolarization and repolarization

essentially the AP

Question 36

what is the physiological correlate of the P wave?

Answer 36

atrial myocyte depolarization - phase 0

Question 37

what is the physiological correlate of the QRS complex?

Answer 37

ventricular myocyte depolarization - phase 0

Question 38

what is the physiological correlate of the PR interval?

Answer 38

all electrical events (depolarization - phase 0s) upstream of ventricular myocytes (atrial myocyte, AV node, bundle, bundle branches, purkinje)

Question 39

what is the physiological correlate of the T wave?

Answer 39

ventricular myocyte repolarization - phase 3

Question 40

what is the physiological correlate of the QT interval?

Answer 40

entire AP for ventricular myocytes (depolarization - plateau - repolarization)

Question 41

what is the physiological correlate of the ST segment?

Answer 41

ventricular myocyte plateau - phase 2