ECG 1 Flashcards
What is the number of phases during the action potential?
4,0,1,2,3
What is the first part of the action potential, and what happens?
Phase 4 - resting phase - sodium and calcium (both positive) enter the cell, increasing charge from -90mv to -70mv
What is the charge within the cell at rest?
-90mv
What is the charge within the cell after phase 4?
-70mv
What is the second phase of the action potential, and what happens?
Phase 0, after the voltage alters in phase 4, a high amount of sodium enter the cell, changing the charge from -70mv to +20mv
What is the charge within the cell after phase 0?
+20mv
What is the third phase of the action potential, and what happens?
Potassium in the cell repels each other. Some potassium leaves the cell and charges from +20mv to +5mv
What is the charge within the cell after phase 1?
+5mv
What is the fourth phase of the action potential, and what happens?
In phase 2, calcium enters the cell and balances the potassium exiting
What is the fifth phase of the action potential, and what happens?
In phase 3, calcium stops entering the cell, and sodium is moved out dropping the charge back to rest
What electrical conduction is occurring at the P wave?
Atrial depolarisation. The SA node firing
What electrical conduction is occurring at the QRS complex?
Ventricular depolarisation. Signal reaches the AV node, then passes down the bundle of his.
What electrical conduction is occurring at the T wave?
Ventricular repolarisation
What is depolarisation during action potential?
The movement of ions into the cell, generating an electrical impulse
What is repolarisation during action potential?
the movement of ions back to resting state
How does the location of the limb lead, change the reading?
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
On an ECG what does aVR mean?
The lead is placed on the Right hand
What is augmented vector?
The fact an ECG augments the view of electrical signals, by amplifying them to make them more prominent
On an ECG what does aVL mean?
The lead is placed on the left arm
On an ECG what does aVF mean?
The lead is placed on the left leg
In terms of time, how can time be inferred from the ECG graph paper?
five 5x5 boxes is 1 second
What is the P-R interval and how long should it be?
Beginning of the P wave, to beginning of the QRS. 0.12 - 0,2 seconds
how long should the QRS complex on average be?
0.08 - 0.12 seconds
What is the 6 step systematic approach for checking ECG?
What is the rate of the ECG? QRS regularity QRS width Are there P waves? Are they all correctly spaced?
