ECG and ECG waves

Question 1

The heart impulse is initially generated where?

Answer 1

SA node

Question 2

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

Answer 2

80-100 times per minute

Question 3

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

Answer 3

Intra-atrial bundles

Question 4

Impulse spread from intra-atrial bundles to where?

Answer 4

AV node

Question 5

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

Answer 5

40-60 times per minute

Question 6

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

Answer 6

70 beats/ min

Question 7

The AV node impulse is transmitted to what?

Answer 7

The bundle of His

Question 8

From the bundle of His the impulse travels where?

Answer 8

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

Question 9

Impulse travels slowest where? Fastest?

Answer 9

Slowest - AV node (0.5 m/sec)

Fastest - purkinjie fibers (4 m/sec)

Question 10

The rate of depolarization is slowest where? Fastest?

Answer 10

Slowest - purkinjie fibers

Fastest - SA node

Question 11

P wave

Answer 11

Atrial depolarization

Question 12

PR interval extends from? How long?

Answer 12

P wave to beginning of Q wave

200 milliseconds

Question 13

What is a 1st degree AV block?

Answer 13

Causes prolonged PR interval (>200 msec)

Question 14

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

Answer 14

2nd degree AV block

Question 15

2nd degree AV block is aka

Answer 15

Mobitz 1 - Wenckebach phenomenon

Question 16

What is a 3rd degree AV block?

Answer 16

No association btw P and QRS complex

Question 17

QRS complex?

Answer 17

Ventricular depolarization (

Question 18

QT interval extends from?

Answer 18

Beginning of Q wave to start of T wave

Question 19

ST segment extends from?

Answer 19

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

Question 20

T wave

Answer 20

Ventricular repolarization

Question 21

Is atrial depolarization seen on ECG?

Answer 21

no

Question 22

Why is atrial depolarization not seen on ECG?

Answer 22

Buried in QRS complex

Question 23

Increase in pressure without change in volume?

Answer 23

isovolumic contraction

Question 24

Isovolumic contraction occurs between what?

Answer 24

Closure of AV valves and opening of aortic valve

Question 25

How much of the blood is ejected?

Answer 25

70 mL of the 120 mL, approx. 60%

Question 26

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

Answer 26

Isovolumic relaxation

Question 27

Isovolumic relaxation occurs between?

Answer 27

Closure of aortic valve and opening of AV valves