ATI LPN
NCLEX Cardiovascular Questions Quizlet Questions
Question 1 of 5
Which structure in the heart initiates action potentials that stimulate contraction of the heart at constant rate of about 100 beats per minute?
Correct Answer: D
Rationale: The sinoatrial (SA) node is the natural pacemaker of the heart, generating rhythmic action potentials that set the heart rate under normal conditions.
Question 2 of 5
Which of the following is not an atrioventricular valve?
Correct Answer: A
Rationale: The aortic valve is a semilunar valve, not an AV valve like mitral, bicuspid, or tricuspid.
Question 3 of 5
Atrioventricular valves prevent backflow of blood into the:
Correct Answer: A
Rationale: Atrioventricular valves prevent backflow of blood into the atria during ventricular contraction.
Question 4 of 5
In the cardiac cycle, the R wave is recorded on an ECG during:
Correct Answer: A
Rationale: The R wave corresponds to ventricular depolarization and contraction.
Question 5 of 5
Which of the following statements is true regarding heart rate regulation?
Correct Answer: A
Rationale: The vagus nerve (parasympathetic) releases acetylcholine to slow the heart rate. Cardiac nerves (sympathetic) increase heart rate, and acetylcholine does not increase it, making only A true.