Electrocardiogram Basics Quiz

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What is the primary purpose of placing electrodes on the skin in an electrocardiogram?

To detect structural abnormalities in heart tissue.

To record electrical potentials generated by cardiac impulses. (correct)

To assess blood flow through the heart.

To measure the physical size of the heart.

Which wave in the electrocardiogram corresponds to atrial depolarization?

R wave

P wave (correct)

Q wave

T wave

What does the T wave indicate in an electrocardiogram?

Atrial contraction.

Ventricular depolarization.

Ventricular repolarization. (correct)

Electrical inactivity of the heart.

What sequence of electrical activity occurs as the heart contracts?

Atrial depolarization, ventricular depolarization, ventricular repolarization. Signup and view all the answers

During depolarization, how does the electrical potential inside cardiac fibers change?

It reverses, becoming slightly positive inside and negative outside. Signup and view all the answers

How long does the T wave occur after ventricular depolarization?

0.25 to 0.35 seconds. Signup and view all the answers

What is typically indicated by the QRS complex in an electrocardiogram?

Ventricular depolarization. Signup and view all the answers

The three waves of the QRS complex are normally identified as which of the following?

Q wave, R wave, S wave. Signup and view all the answers

What occurs immediately after the depolarization wave reaches its peak?

Repolarization begins Signup and view all the answers

At which point does no potential get recorded in an electrocardiogram?

During complete polarization Signup and view all the answers

What is the period during which the ventricles remain contracted?

From the P wave to the T wave Signup and view all the answers

What can obscure the atrial T wave in an electrocardiogram?

The QRS complex Signup and view all the answers

When does the atrial repolarization wave occur relative to the P wave?

0.15 to 0.20 seconds after the P wave Signup and view all the answers

What is observed on the electrocardiogram when the muscle is partly polarized and partly depolarized?

Current flow is detected Signup and view all the answers

What indicates the beginning of ventricular contraction on the electrocardiogram?

The QRS complex Signup and view all the answers

Which stage completes the repolarization process in a muscle fiber?

When both electrodes are positive Signup and view all the answers

In which direction does the current primarily flow during most of the depolarization cycle of the heart?

From the base of the heart to the apex Signup and view all the answers

What is the significance of the average direction of current flow reversing just before depolarization is complete?

It allows for the last part of the heart to become depolarized Signup and view all the answers

How are limb leads in an electrocardiogram created?

By combining two electrodes located on different sides of the heart Signup and view all the answers

What happens when the right arm connection to the chest is electronegative with respect to the left arm in limb lead I?

The electrocardiograph records positively above the zero voltage line Signup and view all the answers

What does the term 'bipolar' signify in the context of an electrocardiogram?

It involves two wires from the electrocardiograph Signup and view all the answers

When the right arm is negative concerning the left leg in limb lead II, how is the EKG affected?

It records positively above the zero voltage line Signup and view all the answers

Which part of the heart is the last to become depolarized?

The outer walls of the ventricles near the base Signup and view all the answers

What is typically observed in the electrocardiogram when the electrode near the base is negative?

The recording will show a positive deflection Signup and view all the answers

What is the heart rate when the interval between two beats is 1 second?

60 beats per minute Signup and view all the answers

Which condition regarding the cardiac muscle cells is true before stimulation?

The exteriors of muscle cells are positive. Signup and view all the answers

How does depolarization affect the electrical charge on cardiac muscle fibers?

It becomes electronegative. Signup and view all the answers

What happens to voltage measurements in relation to depolarization in the heart?

They last only a few milliseconds. Signup and view all the answers

In terms of electrical current flow, how does the distribution in the ventricles occur?

From the electronegative inside to the electropositive outside. Signup and view all the answers

Where does the cardiac impulse first arrive in the ventricles?

In the septum. Signup and view all the answers

What is the role of surrounding fluids in relation to the heart's electrical conductivity?

They enhance the conduction of electricity. Signup and view all the answers

What direction does the average current flow in relation to the heart's anatomy?

Negativity toward the base and positivity toward the apex. Signup and view all the answers

How long does it take for some ventricular muscle fibers to begin repolarizing after depolarization starts?

0.20 s Signup and view all the answers

What is the normal duration of the T wave in an electrocardiogram?

About 0.15 s Signup and view all the answers

What does each 25 mm interval on the horizontal axis of the electrocardiogram represent?

1 second Signup and view all the answers

What is the normal value of the P-Q interval in an electrocardiogram?

0.16 seconds Signup and view all the answers

What voltage can the QRS complex reach when electrodes are correctly placed over the ventricles?

3 to 4 millivolts Signup and view all the answers

Which interval represents the contraction of the ventricle in an electrocardiogram?

Q-T interval Signup and view all the answers

What is the relationship between heart rate and the time interval between successive heartbeats?

Heart rate is the inverse of the time interval Signup and view all the answers

How is the voltage of waves in the normal EKG affected?

By the distance from the heart and electrode placement Signup and view all the answers

What is the configuration of electrodes for limb lead III?

Left arm negative, left leg positive Signup and view all the answers

Which leads primarily record negative QRS complexes due to their proximity to the heart base?

Leads V1 and V2 Signup and view all the answers

What is the primary reason for minute abnormalities in the ventricles affecting EKG recordings?

The heart surfaces being close to the chest wall Signup and view all the answers

In augmented unipolar limb leads, when the positive terminal is connected to the left leg, what is the name of that lead?

aVF lead Signup and view all the answers

Which leads are primarily positive due to their proximity to the heart apex?

Leads V4, V5, and V6 Signup and view all the answers

What connects the negative electrode in the chest leads during an EKG recording?

To all three limbs equally Signup and view all the answers

What is the implication of the direction of electropositivity during ventricular depolarization in chest leads?

It causes positive recordings in chest leads Signup and view all the answers

In the context of chest leads, what does the term 'indifferent electrode' refer to?

An electrode connected through equal resistances to multiple limbs Signup and view all the answers