Which of the following statements about heart rate (HR) is correct?
A 40-year-old person would have an expected maximum HR of 160 bpm.
Resting HR decreases from infancy to young adulthood.
Maximum HR is independent of age and remains around 220 bpm throughout life.
Newborns typically have a resting HR of around 75 bpm.
The Correct Answer is B
A. A 40-year-old person would have an expected maximum HR of 160 bpm: Maximum heart rate is estimated using the formula 220 minus age. For a 40-year-old, the expected maximum HR would be approximately 180 bpm, not 160 bpm. This formula provides a general guideline for exercise and stress testing.
B. Resting HR decreases from infancy to young adulthood: Resting heart rate is higher in infants (typically 120–160 bpm) due to higher metabolic demands and smaller stroke volume. As the cardiovascular system matures and stroke volume increases, resting HR gradually decreases through childhood into young adulthood, stabilizing around 60–100 bpm in healthy adults.
C. Maximum HR is independent of age and remains around 220 bpm throughout life: Maximum heart rate declines with age due to physiological changes in the sinoatrial node and cardiac responsiveness to sympathetic stimulation. It is not constant at 220 bpm; instead, it decreases roughly 1 bpm per year after adolescence.
D. Newborns typically have a resting HR of around 75 bpm: Newborns normally have a resting HR between 120–160 bpm due to their high metabolic rate and limited stroke volume. A HR of 75 bpm in a newborn would be abnormally low and may indicate bradycardia or cardiac compromise.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Correct answer: True
Surface electrodes placed on the skin at specific anatomical locations detect the electrical impulses generated by the heart during depolarization and repolarization. These electrodes capture changes in voltage as the cardiac conduction system, including the SA node, AV node, bundle branches, and Purkinje fibers, propagates impulses through the atria and ventricles. The collected signals are transmitted to an electrocardiograph, which records the heart’s electrical activity as an electrocardiogram (ECG or EKG). This test provides critical information about heart rate, rhythm, conduction pathways, and possible ischemic or structural cardiac abnormalities.
Correct Answer is ["A","B","C","D","E"]
Explanation
Rationale
A heart attack, or myocardial infarction, occurs when blood flow through a coronary artery is obstructed, leading to ischemia and damage to the heart muscle. This affects the myocardium supplied by the blocked artery, most often the left ventricle, which is critical for systemic circulation. Physiologically, ischemia triggers chest discomfort or pressure, often radiating to the arm, jaw, or back, due to nerve stimulation and inflammatory responses. Additional symptoms include shortness of breath from reduced cardiac output, fatigue from impaired perfusion, nausea from vagal stimulation, and lightheadedness from hypotension or arrhythmias, reflecting the heart’s decreased ability to meet the body’s metabolic demands.
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