Electrocardiogram waveforms

Question 1

Principle Wave forms

Answer 1

P wave, QRS complex, T wave

Question 2

The principle segments

Answer 2

PR segment, and the ST segment

Question 3

The intervals

Answer 3

PR interval, QRS interval, and the QT interval

Question 4

What does the P wave represent?

Answer 4

corresponds to atrial depolarization produced by the propagation of the impulse from the SA node, through the atria
-atrial contraction takes place milliseconds after depolarization

Question 5

What does the PR interval indicate

Answer 5

the PR interval from the beginning of the P wave to the beginning of the QRS complex reflects the time required for atrial depolarization and the delay of the impulse at the AV node

Question 6

What does the PR segment indicate?

Answer 6

the PR segment, the time immediately following the p wave to the beginning of the QRS complex, reflects the delay at the AV node

Question 7

What does the QRS complex indicate?

Answer 7

corresponds to ventricular depolarization

• ventricular contraction occurs after the QRS complex in the ST segment
• atrial repolarization also occurs during ventricular contraction, that waveform is not visible but buried in the QRS complex

Question 8

What does the T wave indicate?

Answer 8

corresponds to ventricular repolarization

Question 9

What does the QT interval reflect?

Answer 9

reflects the time required for ventricular depolarization and repolarization

Question 10

Depolarization

Answer 10

movement of ions preceding and facilitating cardiac mechanical contraction

Question 11

Repolarization

Answer 11

movement of ions back to the resting state, the cardiac resting membrane potential of -90mV, to allow for the initiation of another action potential

Question 12

Cardiac Action Potential

Answer 12

a process in which the membrane potential, the difference in charge between the inferior and exterior of the cell, changes or goes up and down in a consistent pattern

Question 13

Absolute refractory period

Answer 13

occurs during and immediately following depolarization

• during this time, the cell is unresponsive to any stimulus
• corresponds to phase 0 through the middle of phase 3

Question 14

Relative refractory period

Answer 14

immediately following the absolute refractory period, this represents a time when a greater-than normal stimulus may initiate an impulse

• corresponds to the end of phase 3
• medications utilized to control irregular heart rhythms or dysrhythmias typically manipulate the movement of ions in some way