The nurse is analyzing a rhythm strip.
What component of the ECG corresponds to the resting state of the client’s heart?
T wave.
U wave.
P wave.
QRS Complex.
The Correct Answer is A
Choice A rationale:
The T wave specifically represents ventricular repolarization, which is the phase of the cardiac cycle when the ventricles return to their resting state after contraction. This is in contrast to the other waves on the ECG, which represent different phases of the cardiac cycle:
The P wave represents atrial depolarization, or the contraction of the atria.
The QRS complex represents ventricular depolarization, or the contraction of the ventricles.
The U wave, while less commonly seen, is thought to represent repolarization of the Purkinje fibers, which are specialized fibers that conduct electrical impulses through the ventricles.
The T wave is typically a smooth, rounded wave that follows the QRS complex. It is usually upright in most leads, but it can be inverted in certain leads, such as aVR.
The shape and duration of the T wave can provide important information about the health of the ventricles. For example, a flattened or inverted T wave can be a sign of myocardial ischemia (reduced blood flow to the heart muscle) or other heart problems.
It is important to note that the T wave does not represent the absolute resting state of the heart, as there is always some electrical activity occurring in the heart muscle. However, it is the closest representation of the resting state that is seen on the ECG.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale:
Systole is derived from the Greek word "sustolē," meaning "contraction." This etymology directly aligns with the physiological process it describes.
During systole, the heart muscle contracts forcefully, generating the pressure necessary to propel blood out of the heart's chambers and into the circulatory system.
This phase is crucial for ensuring adequate blood flow to all tissues and organs, delivering oxygen and nutrients and removing waste products.
It's initiated by electrical signals generated by the sinoatrial node (SA node), the heart's natural pacemaker.
The electrical impulse travels through the heart's conduction system, triggering a coordinated contraction of the atria and ventricles.
Atrial systole occurs first, contributing to ventricular filling.
Ventricular systole follows, generating the powerful force that propels blood into the pulmonary artery (from the right ventricle) and the aorta (from the left ventricle).
Systolic blood pressure, the higher number in a blood pressure reading, measures the pressure in the arteries during ventricular systole.
Choice B rationale:
This choice describes diastole, the opposite phase of the cardiac cycle.
During diastole, the heart muscle relaxes, allowing the chambers to refill with blood.
Diastole is essential for proper heart function, ensuring that the heart can adequately fill with blood before the next systolic contraction.
Choice C rationale:
This choice refers to cardiac output, which is the total volume of blood pumped by the heart per minute.
Cardiac output is influenced by both heart rate and stroke volume (the amount of blood ejected from the ventricle with each contraction). Choice D rationale:
This choice describes ejection fraction, which is the percentage of blood that fills the ventricles during diastole that is then pumped out during systole.
Ejection fraction is a measure of the heart's pumping efficiency.
Correct Answer is ["A","B","D"]
Explanation
Choice A rationale:
Pain relief is a primary benefit of morphine administration in the setting of myocardial infarction.
Pain can trigger a stress response, leading to increased heart rate, blood pressure, and myocardial oxygen demand.
Morphine effectively reduces pain, thereby lessening the stress response and its detrimental effects on the heart.
This helps to minimize myocardial ischemia and potential further damage to the heart muscle.
Pain control also improves patient comfort and overall well-being, which can indirectly contribute to better cardiac outcomes.
Choice B rationale:
Sedation is another important benefit of morphine in this context.
It promotes rest and relaxation, which can lower heart rate, blood pressure, and myocardial oxygen demand.
This is crucial for patients with myocardial infarction, as their hearts require reduced workload to heal and recover.
Sedation also helps to alleviate anxiety and agitation, which can further strain the heart.
By inducing a state of calmness, morphine can indirectly protect the heart from additional stress.
Choice C rationale:
While morphine does have diuretic effects, increasing urinary output is not a primary goal in the management of myocardial infarction.
In fact, excessive diuresis could potentially lead to dehydration and hypotension, which could be detrimental to cardiac function.
Therefore, while morphine may slightly increase urine output, this is not a major reason for its use in this setting.
Choice D rationale:
Decreasing myocardial demand is a key benefit of morphine administration in patients with myocardial infarction.
Morphine achieves this by:
Reducing pain and the associated stress response
Promoting sedation and relaxation
Diminishing anxiety and agitation
Exerting a direct vasodilatory effect on blood vessels
This collective action of morphine leads to a decrease in heart rate, blood pressure, and the heart’s overall workload.
As a result, the heart requires less oxygen and experiences reduced strain, allowing for better healing and recovery following a myocardial infarction.
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