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My NBCE Part 1 - Cardiovascular Physiology > ECG and ECG waves > Flashcards

Flashcards in ECG and ECG waves Deck (27)
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1

The heart impulse is initially generated where?

SA node

2

SA node has its own intrinsic rhythm/rate of depolarization of what?

80-100 times per minute

3

Impulse from SA node spreads through the __________ causing both atria to contract simultaneously.

Intra-atrial bundles

4

Impulse spread from intra-atrial bundles to where?

AV node

5

AV node has intrinsic rhythmicity/rate of depolarization of what?

40-60 times per minute

6

When SA nodal rhythm is superimposed on AV nodal rhythm, what is the result?

70 beats/ min

7

The AV node impulse is transmitted to what?

The bundle of His

8

From the bundle of His the impulse travels where?

To right and left bundle branches located in the muscular part of interventricular septum.

9

Impulse travels slowest where? Fastest?

Slowest - AV node (0.5 m/sec)
Fastest - purkinjie fibers (4 m/sec)

10

The rate of depolarization is slowest where? Fastest?

Slowest - purkinjie fibers
Fastest - SA node

11

P wave

Atrial depolarization

12

PR interval extends from? How long?

P wave to beginning of Q wave
200 milliseconds

13

What is a 1st degree AV block?

Causes prolonged PR interval (>200 msec)

14

This AV block causes progressive prolonged PR interval with dropped beats.

2nd degree AV block

15

2nd degree AV block is aka

Mobitz 1 - Wenckebach phenomenon

16

What is a 3rd degree AV block?

No association btw P and QRS complex

17

QRS complex?

Ventricular depolarization (

18

QT interval extends from?

Beginning of Q wave to start of T wave

19

ST segment extends from?

End of S wave to start of T wave - isoelectric line

20

T wave

Ventricular repolarization

21

Is atrial depolarization seen on ECG?

no

22

Why is atrial depolarization not seen on ECG?

Buried in QRS complex

23

Increase in pressure without change in volume?

isovolumic contraction

24

Isovolumic contraction occurs between what?

Closure of AV valves and opening of aortic valve

25

How much of the blood is ejected?

70 mL of the 120 mL, approx. 60%

26

What is a decrease in pressure without a change in volume?

Isovolumic relaxation

27

Isovolumic relaxation occurs between?

Closure of aortic valve and opening of AV valves