Physiological Basis Of The EKG

Question 1

What does the ECG measure

Answer 1

Extracellular potential

Question 2

Wen is a deflection caused with an ECG

Answer 2

Part of the cardiac excitable tissue is at a different membrane potential than the rest of the heart

Question 3

Why does the ECG not measure difference between the atria and the ventricles

Answer 3

Electrical insulation from the fibrous skeleton

Question 4

When there is a depolarization, what is happening in the extracellular portion that the ECG records

What about for Repol.

Answer 4

• outside (+ inside)

+ outside (- inside)

Question 5

Ventricles depol in what direction

What about repol

Answer 5

R to L
Apex to Base
Interior to Exterior

Just the reverse for repol

Question 6

All atrial cells are depolarized when

Answer 6

At the end of the P wave

Question 7

All ventricular cells are depolarized when

Answer 7

By the ST segment

Question 8

Define the PR interval

Answer 8

Beg of atrial depol to delay in AV node

Question 9

Define QT interval

Answer 9

Vent. Depol

Question 10

Define PR segment

Answer 10

End of atrial depol, this is solely the AV delay

Question 11

What does aVF read

Answer 11

(RA + LA) to LL

Question 12

What does aVR read

Answer 12

(LL + LA) to RA

Question 13

What does aVL read

Answer 13

(LL + RA) to LA

Question 14

V1 and V2 are generally what

Answer 14

Negative

Question 15

V4, V5, V6 are generally what

Answer 15

Positive

Question 16

Each of the precordial leads acts as what

Answer 16

A positive electrode

Question 17

Elevation in the inferior leads means a blockage where

Answer 17

RCA

Question 18

Elevation in the septal leads means a blockage where

Answer 18

The LAD

Question 19

Elevation in the anterior leadfs means a blockage where

Answer 19

LAD

Question 20

Elevation in the Lateral leads means a blockage where

Answer 20

The circumflex A.

Question 21

Define mean electrical axis deviation

Answer 21

Average direction of spreading AP in ventricles

Question 22

What can cause a shift in the axis

Answer 22

Hypertrophy, MI, BBB

Question 23

Lead I Positive and Negative directions

Answer 23

Positive - R - L

Negative - L - R

Question 24

Define aVF Positive and negative directions

Answer 24

Pos - top to bottom

Neg. - bottom to top

Question 25

If lead I is negative, what does this mean

Answer 25

R axis deviation

RVH

Question 26

Is lead I is positive, but AvF is negative, what does this mean

Answer 26

left axis deviation

LVH

Question 27

The p-wave begins before what

Answer 27

Atrial contraction

Question 28

The QRS complex begins before what

Answer 28

Ventricular contraction

Question 29

The T wave begins before what

Answer 29

Ventricular relaxation