ATI RN
Cardiovascular System Exam
1. Which fibers distribute the electrical impulse to the ventricles, causing them to contract?
- A. Purkinje fibers
- B. SA node
- C. AV node
- D. Bundle of His
Correct answer: A
Rationale: The correct answer is Purkinje fibers. Purkinje fibers are specialized conducting fibers that distribute the electrical impulse to the ventricles, leading to their contraction. The SA node (sinoatrial node) is responsible for initiating the electrical impulse in the heart, the AV node (atrioventricular node) delays the impulse to allow for proper atrial contraction before ventricular contraction, and the Bundle of His transmits the impulse from the AV node to the ventricles. Therefore, choices B, C, and D are not the correct options for fibers directly distributing the impulse to the ventricles.
2. What is the term that describes the inability of cardiac cells to respond to a new stimulus while they are still in contraction from a previous stimulus?
- A. Refractoriness
- B. Excitability
- C. Contractility
- D. Automaticity
Correct answer: A
Rationale: Refractoriness is the correct term to describe the inability of cardiac cells to respond to a new stimulus while they are still in contraction from a previous stimulus. This period is essential for the heart to complete its contraction and relaxation phases without interference. Excitability refers to the ability of cells to respond to stimuli, not the inability to respond. Contractility is the force of cardiac muscle contraction, and automaticity is the ability of cardiac cells to generate electrical impulses spontaneously, which are not relevant to the described scenario.
3. What condition involves a weakened and bulging aorta, the main artery in the body, potentially leading to rupture?
- A. Aortic aneurysm
- B. Arterial stenosis
- C. Pulmonary embolism
- D. Deep vein thrombosis
Correct answer: A
Rationale: An aortic aneurysm is a condition characterized by the weakening and bulging of the aorta, the body's main artery. If left untreated, this bulging may lead to a rupture, causing severe complications. Arterial stenosis refers to the narrowing of an artery, not the weakening and bulging seen in an aortic aneurysm. Pulmonary embolism involves a blockage in the pulmonary artery, which is different from the weakening and bulging in an aortic aneurysm. Deep vein thrombosis is the formation of a blood clot in a deep vein, not related to the condition described in the question.
4. Which term refers to the contraction phase of the heart when blood is ejected from the chambers?
- A. Systole
- B. Diastole
- C. Contractility
- D. Afterload
Correct answer: A
Rationale: The correct answer is A, systole. Systole is the phase of the cardiac cycle when the heart contracts and pumps blood out of the chambers. During diastole (choice B), the heart relaxes and fills with blood, contrasting with systole. Contractility (choice C) refers to the ability of the heart to contract effectively. Afterload (choice D) is the pressure the heart must work against to eject blood during systole.
5. The nurse is giving digoxin to a client. What is the most important parameter to check before administration?
- A. Heart rate
- B. Blood pressure
- C. Respiratory rate
- D. Oxygen saturation
Correct answer: A
Rationale: The correct answer is A: Heart rate. Before administering digoxin, it is crucial to check the client's heart rate because digoxin can cause bradycardia, an abnormally slow heart rate. Monitoring the heart rate is essential to prevent potential complications associated with digoxin therapy. Choices B, C, and D are less critical parameters to assess before administering digoxin. While blood pressure is also important to monitor during digoxin therapy, the most crucial parameter to check due to the medication's potential effect on heart rate is the heart rate itself.
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