Quiz 2

Question 1

What are the two basic stages of the cardiac cycle?

Answer 1

Diastole- long. Ventricles relaxing, preparing for another pump

Systole- very short (0.12 seconds). Actual pumping of blood

Question 2

What is vector?

Answer 2

Electrical energy generated by heart creates a path the action potential takes as it spreads through myocardium

Vector offers both magnitude and direction

Question 3

What is the hearts normal conductive pathway?

Answer 3

Down and to the left

Question 4

What is it called when the action potential moves in an abnormal direction?

Answer 4

Axis deviation

Question 5

What are the 5 stages of cardiac polarization?

Answer 5

Polarized/resting potential (+ outside) > depolarizing > depolarized (- outside) > repolarization (requires ATP)

Question 6

What is the electrical path of the heart?

Answer 6

SA node generates action potential > AV node > bundle of his > 3 bundle branches > perkinje fibres

Question 7

What coronary artery feeds into the SA node?

Answer 7

Posterior descending artery

Question 8

What happens if the SA node stops working?

Answer 8

AV node can take over at 40bpm (as opposed to SA 60bpm)

Question 9

What is the rhythm of the heart called?

Answer 9

Sinus rhythm (when electrical activity is originating from SA node)

Question 10

What is lead II?

Answer 10

Negative electrode on right arm, positive electrode on left hip

Question 11

What does Lead II show?

Answer 11

Upright QRS and prominent p wave- used for rhythm assessment

Question 12

What is baseline?

Answer 12

The ‘flatline’ between T and P waves

Question 13

What is the P wave?

Answer 13

Consistent round, smooth wave in front of every QRS

Indicated atrial depolarization (blood being pumped into ventricles)

Question 14

Do you see atrial repolarization on an EKG?

Answer 14

No. Hidden by ventricular depolarization (QRS)

Question 15

What is the QRS?

Answer 15

Ventricular depolarization

Q down (may not be present)

R up then down

S down (may not be present)

Takes .12 seconds- longer could be lethal

Question 16

What is the T wave?

Answer 16

Ventricular repolarization

Larger than P wave

Question 17

What are 4 characteristics of myocardial cells?

Answer 17

Automaticity- not needing constant supervision or higher thinking

Excitability

Conductivity

Contractability

Question 18

What is the normal speed of EKG graph paper?

Answer 18

25 mm/sec

Question 19

How much time does one small box indicate on normal speed EKG paper?

Answer 19

0.04 seconds

Large box = 5 small boxes = 0.20 seconds

Question 20

What do the two axis’ on an EKG graph mean?

Answer 20

y- magnitude (in mV) one small box = 0.1 mV

Also measured in mm height

X- time

Question 21

What happens if you run EKG paper faster?

Answer 21

graph becomes more spaced out and easier to read. Goof for infants (160-180 bpm)

Question 22

What halogens if you increase gain on an EKG?

Answer 22

Magnitude measurements become more pronounces, possibly making graph easier to read

Question 23

What is PR interval?

Answer 23

The time between the P wave and the Q wave

Usually 0.12-0.20 seconds

Atrial depolarization

Long PR interval can mean heart block

Question 24

What is the ST segment?

Answer 24

Isoelecetric flat between end of QRS and beginning of T

During myocardial infarction, ST will be elevated off baseline (STEMI- ST elevated myocardial infarct)

Question 25

What is the QT interval?

Answer 25

Time between beginning of ventricular depolarization and end of repolarization

(Q and T waves)

Long QT segment means slow conduction, and often indicates drug toxicity

Question 26

What are the defining characteristics of sinus rhythm?

Answer 26

1- normal ventricular rate

2-regular pattern

3-P waves all look identical, and are all before QRS

4- normal conduction time through all intervals

5- all QRS’s loo, the same

Question 27

What are the 3 ways to calculate HR?

Answer 27

6 second method- count # of QRS in 30 large squares (60 seconds) and multiply by 10 for BPM (not very accurate)

300 method- find QRS in large square, count # of large squares until next QRS, divide by 300

1500 method- same as 300, but with small squares. Divide by 1500

Question 28

What are the various non-SR rhythms?

Answer 28

Atrial- different P waves

Ventricular- different QRS. If wide, lethal

Heart block- long interval times

Question 29

What do the bundle of his, bundle branches, and purkinje fibres do?

Answer 29

Stimulate deploarization in the ventricles