EKG: Chapter 2 Electrophysiology

One small block on the EKG paper measures ______ seconds

0.04

Normal QRS interval in ______ seconds or less than three small blocks

0.12

On EKG paper, one big block represents

0.20 seconds

The ventricles inherent rate is

20-40

If the sinus node, atria, and AV node all fail, the heart rate will be between

20-40 bpm

The PR INTERVAL would be considered abnormal if it measured _______ small blocks on the EKG paper

6

The normal inherent rate of the sinus node as a pacemaker is

60-100 bpm

The PR interval measures the time it takes for the impulse to travel from the

Atria to the Ventricle

What electrical event must occur for atrial contraction to occur?

Atrial depolarization

Which of the following ions has a direct effect on ventricular muscle contraction?

Calcium

Which of the following is NOT true?

Cardiac cells can contract without having been depolarized.

Which of the following characteristics of heart cells is mechanical

Contractility

Depolarization is a(n)

Electrical event that should result in muscle contraction

During the absolute refractory period, only a strong stimulus can result in depolarization (t/f)

False

The cardiac cell, at rest, has a transmembrane potential of +20mV (t/f)

False

After the sinus node initiates an impulse, where does the impulse go next?

Interatrial tracts

What is TRUE about the following intervals: PR 0.14 QRS 0.08

Intervals are normal

Which of the following correctly describes the relative refractory period?

It is the period in which only a strong impulse can cause another depolarization

Which of these statements about the sinus node is FALSE

It is the slowest pacemaker of the heart

Atrial depolarization is represented on the EKG is a _____

P wave

If the sinus node and atria both fail, the ______ will be absent on the rhythm strip

P wave

The PR segment is located between the

P wave and QRS complex

The baseline on the EKG strip is considered to be the

PR segment

A negative deflection that occurs before a positive one is labeled is a _____ wave

Q

The ST segment is located between the

QRS complex and the T wave

Phase 0 of the action potential corresponds with what wave or complex on the EKG

QRS complex?

An upward deflection is called a(n)

R wave

A QRS complex with one positive deflection followed by one negative deflection would be labeled

RS

Normal conduction begins with the pacemaker of the heart is the

SA node

The wave or complex that represents ventricular repolarization is the

T wave

The P wave represents atrial depolarization (t/f)

True

The baseline is a flat line from which the waves and complexes take off (t/f)

True

The normal rate of the sinus node is 60-100 bpm (t/f)

True

The polarized cardiac cell is electrically negative (t/f)

True

Arrhythmias are _______ heart rhythms

abnormal

If a heart rhythm is slower than normal it is called a(n)

arrhythmia

The P wave represents

atrial depolarization

The pacemaker is the ______ of the conduction system of the heart

beginning

Transmembrane potential is the electrical charge at the ______

cell membrane

Contractility is the ability of a cardiac cell to

contract

In the action potential, phase 0 is

depolarization

A beat that appears on the rhythm strip after a long pause and causes a slower rhythm is called a(n)

escape beat

Cardiac cell stimulus during the absolute refractory period often results in very fast, dangerous rhythms.(t/f)

false

The PR segment is a flat line located between the QRS complex and T wave (t/f)

false

The ST segment is a flat line from which the waves and complexes take off (t/f)

false

The normal pacemaker of the heart is the AV node (t/f)

false

The EKG is the recording of the

heart's electrical activity

The term "repolarization" refers to?

heart's electrical activity

The electrical impulse travels through the _____ to get from the atrium to the AV node

internodal tracts

The normal ST segment is

isoelectric line

The cardiac cell at rest has what kind of electrical charge?

negative charge

Depolarization is the changing of the cardiac cell is to an electrically ______ charge

neutral

The area of the conduction system that initiates the impulse is called the

pacemaker

The job of the cardiac conduction system's pacemaker is to

propagate electrical impulses, conduct electrical impulses, and cause depolarization of the myocardial cells

In the action potential, phase 3 is

rapid repolarization

Refractory means to______

resist

The normal pacemaker of the heart is the

sinus node

On a rhythm strip, the P wave is normally

small

+20 mV

transmembrane potential at the conclusion of phase 0 of the action potential

If the PR interval is 0.10 seconds, the time it takes for the impulse to travel from the atrium down to the ventricle is abnormal (t/f)

true

The PR interval measures the time it takes for the impulse to travel from the atrium down to the ventricle (t/f)

true

A QRS complex that has both an R and R' wave will have

two positive deflections

The relative refractory period extends from the

upstroke of the T wave to the end of the T wave

If a pacemaker becomes irritable and fires at a faster than normal rate, _______ will occur

usurpation

The pacemaker with the slowest inherent rate is the ______

ventricle

The QRS complex represents

ventricular depolarization

The T wave represents

ventricular repolarization