this refers to the degree of myocardial fiber stretch before contraction it is related to the volume of blood distending the ventricles at the end of
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Nursing Elites

ATI RN

Cardiovascular System Practice Exam

1. What term refers to the degree of myocardial fiber stretch before contraction, related to the volume of blood distending the ventricles at the end of diastole, and determined by the amount of venous return?

Correct answer: A

Rationale: The correct answer is A: Preload. Preload is the degree of myocardial fiber stretch before contraction, influenced by the volume of blood returning to the heart. This parameter is related to the amount of blood in the ventricles at the end of diastole. Choice B, Afterload, refers to the pressure or resistance that the ventricles must overcome to eject blood. Choice C, Contractility, is the intrinsic ability of the heart muscle to contract. Choice D, Ejection fraction, is the percentage of blood pumped out of the ventricles with each contraction.

2. The nurse is caring for a client on digoxin with a heart rate of 48 bpm. What is the nurse’s priority action?

Correct answer: A

Rationale: In this scenario, the nurse's priority action should be to hold the digoxin and notify the healthcare provider. A heart rate of 48 bpm is low, and digoxin, being a medication that can further decrease the heart rate, should be withheld. Administering the digoxin as ordered (Choice B) would not be appropriate in this situation as it can exacerbate bradycardia. Atropine (Choice C) is not the initial treatment for this scenario; holding the digoxin is the first action. Increasing the dose of digoxin (Choice D) would be contraindicated due to the client's bradycardia. Therefore, the correct action is to hold the digoxin and inform the healthcare provider for further guidance.

3. This term refers to a change in the inotropic state of the muscle without a change in myocardial fiber length.

Correct answer: A

Rationale: The correct answer is A: Contractility. Contractility specifically refers to the change in the force of contraction of the heart muscle without changing its length. In this scenario, the focus is on the change in the inotropic state of the muscle, which directly relates to contractility. Choice B, Excitability, refers to the ability of a cell to respond to a stimulus, not specifically related to changes in contractile force. Choice C, Refractoriness, pertains to the period during which a cell is unresponsive to a new stimulus. Choice D, Automaticity, refers to the ability of cardiac cells to spontaneously generate electrical impulses.

4. Which term refers to the relaxation phase of the heart, during which the chambers fill with blood?

Correct answer: A

Rationale: The correct answer is A, Diastole. Diastole is the phase of the cardiac cycle when the heart muscles relax, allowing the chambers to fill with blood. Choice B, Systole, is incorrect as systole is the contraction phase of the heart when blood is pumped out of the chambers. Choice C, Refractoriness, refers to a period during which the heart muscle is unresponsive to stimuli. Choice D, Automaticity, relates to the heart's ability to generate its own electrical impulses.

5. Which valves close during ventricular systole and open during ventricular diastole?

Correct answer: B

Rationale: The correct answer is B: Atrioventricular Valves. The atrioventricular (AV) valves, including the mitral valve and tricuspid valve, close during ventricular systole to prevent backflow of blood from the ventricles into the atria. They open during ventricular diastole to allow blood flow from the atria into the ventricles. Semilunar valves, choice A, are located at the exits of the ventricles and prevent backflow into the ventricles. The mitral valve and tricuspid valve, choices C and D, are specific types of AV valves.

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