ECG 1

Question 1

What is the number of phases during the action potential?

Answer 1

4,0,1,2,3

Question 2

What is the first part of the action potential, and what happens?

Answer 2

Phase 4 - resting phase - sodium and calcium (both positive) enter the cell, increasing charge from -90mv to -70mv

Question 3

What is the charge within the cell at rest?

Answer 3

-90mv

Question 4

What is the charge within the cell after phase 4?

Answer 4

-70mv

Question 5

What is the second phase of the action potential, and what happens?

Answer 5

Phase 0, after the voltage alters in phase 4, a high amount of sodium enter the cell, changing the charge from -70mv to +20mv

Question 6

What is the charge within the cell after phase 0?

Answer 6

+20mv

Question 7

What is the third phase of the action potential, and what happens?

Answer 7

Potassium in the cell repels each other. Some potassium leaves the cell and charges from +20mv to +5mv

Question 8

What is the charge within the cell after phase 1?

Answer 8

+5mv

Question 9

What is the fourth phase of the action potential, and what happens?

Answer 9

In phase 2, calcium enters the cell and balances the potassium exiting

Question 10

What is the fifth phase of the action potential, and what happens?

Answer 10

In phase 3, calcium stops entering the cell, and sodium is moved out dropping the charge back to rest

Question 11

What electrical conduction is occurring at the P wave?

Answer 11

Atrial depolarisation. The SA node firing

Question 12

What electrical conduction is occurring at the QRS complex?

Answer 12

Ventricular depolarisation. Signal reaches the AV node, then passes down the bundle of his.

Question 13

What electrical conduction is occurring at the T wave?

Answer 13

Ventricular repolarisation

Question 14

What is depolarisation during action potential?

Answer 14

The movement of ions into the cell, generating an electrical impulse

Question 15

What is repolarisation during action potential?

Answer 15

the movement of ions back to resting state

Question 16

How does the location of the limb lead, change the reading?

Answer 16

A lead above the heart will see the signal move away from its location (down the heart), so appear negative
A lead below the heart will see the signal move towards it, so appear positive

Question 17

On an ECG what does aVR mean?

Answer 17

The lead is placed on the Right hand

Question 18

What is augmented vector?

Answer 18

The fact an ECG augments the view of electrical signals, by amplifying them to make them more prominent

Question 19

On an ECG what does aVL mean?

Answer 19

The lead is placed on the left arm

Question 20

On an ECG what does aVF mean?

Answer 20

The lead is placed on the left leg

Question 21

In terms of time, how can time be inferred from the ECG graph paper?

Answer 21

five 5x5 boxes is 1 second

Question 22

What is the P-R interval and how long should it be?

Answer 22

Beginning of the P wave, to beginning of the QRS. 0.12 - 0,2 seconds

Question 23

how long should the QRS complex on average be?

Answer 23

0.08 - 0.12 seconds

Question 24

What is the 6 step systematic approach for checking ECG?

Answer 24

What is the rate of the ECG?
QRS regularity
QRS width
Are there P waves?
Are they all correctly spaced?

Question 25

How can bpm be calculated using an ECG?

Answer 25

300 divided by the amount of boxes between the R wave of two QRS waves

Question 26

How can bpm be calculated on an irregular heart beat using an ECG?

Answer 26

Count the amount of beats in 6 seconds (30 boxes), then times by 10 to get a minute

Question 27

What is lead 2?

Answer 27

A combination between the results from electrodes on the right arm and left leg