100% Correct Answers
Question 31 of 50
2.0/ 2.0 Points
Which of the following statements are considered to be normal?
A. Normal heart rates vary from 30 beats/minute up to 200 beats/minute.
B. A heart rate less than or equal to 60 beats/minute is called bradycardia.
C. A heart rate greater than or equal to 100 or 120 beats/minute is called tachycardia.
D. A person’s heart rate will change depending on the needs of the body.
E. B, C, and D are all correct.
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Question 32 of 50
2.0/ 2.0 Points
In case of damage to the SA node, there are other sites in the heart which can depolarize
and establish a rate of contraction of the cardiac muscle cells. For example:
, A. The AV node itself can depolarize at rates of 40-60 times per minute.
B. The cardiac muscle cells themselves can depolarize spontaneously at about
10 times per minute.
C. The bundle branches can each depolarize at rates of approximately 50-60
times per minute.
D. The Purkinje fibers can themselves depolarize at rates of about 5-10 times per minute.
E. Various other cells in either atrium can establish a heart rate of 100-140
beats per minute.
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Question 33 of 50
0.0/ 2.0 Points
Which of the following statements about the left ventricle is/are true?
A. Blood entering the left ventricle is usually quite low in its oxygen concentration.
, B. Blood exits the left ventricle through the aortic valve into the aorta.
C. The left ventricle contracts at the same time as the left atrium.
D. The wall of the left ventricle is very thin but also is very strong.
E. Both B and D are correct.
Feedback: The left ventricle has a very thick and strong wall. It pumps highly
oxygenated blood into the systemic circulation via the aortic valve. The right and left
ventricles both contract at the same time.
Question 34 of 50
2.0/ 2.0 Points
By careful placement of surface electrodes on the body, it is possible to record the
complex, compound electrical signal of the heart. This tracing of the electrical signal is the
electrocardiogram (ECG). Which of the following statements is/are true?
A. A resting ECG usually takes approximately 1-2 hours to be recorded.
B. A normal ECG shows one single spike representing the contraction of the entire heart.
C. To record an ECG, 12-electrodes are placed in a circular pattern around
the person’s chest.