Phrm 123 Quiz 3 (Answered) 123 Questions
and Correct Answers. 100% Verified.
2025/2026.
What is an ECG/EKG?
provides a visual representation of the spread of electrical excitation through the heart as detected
on the surface of the body
What do ECG electrodes record?
the overall direction and magnitude of the electrical events
What does an ECG tracing display?
the electrical events as positive and negative deflections over time
What are ECGs important in diagnosing?
heart problems
What is an idealized ECG shape useful for understanding?
differences between the different types of ECGs and differences within a single patient in different
circumstances
What can the components of an ECG be correlated with?
the electrical activity of the atrial and ventricular muscle
What is the P wave produced by?
atrial depolarization
What is the PR interval?
onset of atrial depolarization to the onset of ventricular depolarization
If a Q wave is present, what is the PR interval called?
PQ interval
What is the PR segment?
end of the P wave to the beginning of the QRS complex
If a Q wave is present, what is the PR segment called?
PQ segment
What is the QRS complex produced by?
ventricular depolarization; atrial repolarization also occurs but its contribution is small and hidden by
the dominant ventricular depolarization
, What is the ST segment?
isoelectric line from the end of the QRS complex to the beginning of the T wave; it is the time when
the ventricles are depolarized
What is the T wave produced by?
ventricular repolarization
What is the approximate duration while at rest with a heart rate of 60BPM of a P wave?
0.10s
What is the approximate duration while at rest with a heart rate of 60BPM of a PR interval?
0.20s
What is the approximate duration while at rest with a heart rate of 60BPM of a QRS complex?
0.08s
What is the approximate duration while at rest with a heart rate of 60BPM of a ST segment?
0.08s
What is the approximate duration while at rest with a heart rate of 60BPM of a T wave?
0.16s
What is the approximate duration while at rest with a heart rate of 60BPM of a QT interval?
0.40s
During exercise, an increase in heart rate corresponds to a shortening of the cardiac cycle in which
intervals?
the time between two successive R waves decreases; most of the shortening occurs in the TP
interval; QT interval also shortens, slightly
What is the important factor to consider on the ECG for segments?
change from the isoelectric line (elevation or depression)
What is the important factor to consider on the ECG for intervals?
duration
What generates an electrical signal which travels along a set conduction pathway?
autorhythmic cells of the heart
What do the autorhythmic cells of the heart ensure?
coordinated contraction of the heart
In a healthy heart, what generates cardiac action potentials at a greater frequency than other
cardiac muscle cells?
Sinoatrial node
and Correct Answers. 100% Verified.
2025/2026.
What is an ECG/EKG?
provides a visual representation of the spread of electrical excitation through the heart as detected
on the surface of the body
What do ECG electrodes record?
the overall direction and magnitude of the electrical events
What does an ECG tracing display?
the electrical events as positive and negative deflections over time
What are ECGs important in diagnosing?
heart problems
What is an idealized ECG shape useful for understanding?
differences between the different types of ECGs and differences within a single patient in different
circumstances
What can the components of an ECG be correlated with?
the electrical activity of the atrial and ventricular muscle
What is the P wave produced by?
atrial depolarization
What is the PR interval?
onset of atrial depolarization to the onset of ventricular depolarization
If a Q wave is present, what is the PR interval called?
PQ interval
What is the PR segment?
end of the P wave to the beginning of the QRS complex
If a Q wave is present, what is the PR segment called?
PQ segment
What is the QRS complex produced by?
ventricular depolarization; atrial repolarization also occurs but its contribution is small and hidden by
the dominant ventricular depolarization
, What is the ST segment?
isoelectric line from the end of the QRS complex to the beginning of the T wave; it is the time when
the ventricles are depolarized
What is the T wave produced by?
ventricular repolarization
What is the approximate duration while at rest with a heart rate of 60BPM of a P wave?
0.10s
What is the approximate duration while at rest with a heart rate of 60BPM of a PR interval?
0.20s
What is the approximate duration while at rest with a heart rate of 60BPM of a QRS complex?
0.08s
What is the approximate duration while at rest with a heart rate of 60BPM of a ST segment?
0.08s
What is the approximate duration while at rest with a heart rate of 60BPM of a T wave?
0.16s
What is the approximate duration while at rest with a heart rate of 60BPM of a QT interval?
0.40s
During exercise, an increase in heart rate corresponds to a shortening of the cardiac cycle in which
intervals?
the time between two successive R waves decreases; most of the shortening occurs in the TP
interval; QT interval also shortens, slightly
What is the important factor to consider on the ECG for segments?
change from the isoelectric line (elevation or depression)
What is the important factor to consider on the ECG for intervals?
duration
What generates an electrical signal which travels along a set conduction pathway?
autorhythmic cells of the heart
What do the autorhythmic cells of the heart ensure?
coordinated contraction of the heart
In a healthy heart, what generates cardiac action potentials at a greater frequency than other
cardiac muscle cells?
Sinoatrial node
