Question 1

Which of the following best describes the function of the AV node delay during the cardiac conduction cycle?

Accepted Answer

It ensures the atria have time to complete systole before ventricular contraction begins.

Question 2

A patient presents with a heart rate of 45 bpm and no visible P waves preceding each QRS complex on their ECG. Which condition is most likely present?

Accepted Answer

Junctional rhythm

Question 3

Which equation correctly calculates stroke volume (SV)?

Accepted Answer

$$SV = EDV - ESV$$

Question 4

During which phase of the cardiac cycle are all heart valves closed and the ventricles are contracting but not yet ejecting blood?

Accepted Answer

Isovolumetric contraction

Question 5

A patient with persistent high blood pressure is at risk for which of the following changes in afterload and stroke volume?

Accepted Answer

Increased afterload and decreased stroke volume

Question 6

Which of the following is a direct effect of sympathetic stimulation on the heart?

Accepted Answer

Increased heart rate and contractility

Question 7

A patient’s ECG shows a progressive lengthening of the PR interval until a QRS complex is dropped. What type of heart block is this?

Accepted Answer

Second-degree AV block, Mobitz Type I (Wenckebach)

Question 8

Which of the following best explains why ventricular fibrillation is life-threatening?

Accepted Answer

It results in the ventricles quivering without effective pumping, leading to no cardiac output.

Question 9

Which of the following statements about the cardiac output (CO) is correct?

Accepted Answer

$$CO = HR 	imes SV$$

Question 10

A patient with left-sided heart failure is most likely to develop which of the following complications?

Accepted Answer

Pulmonary edema

Question 11

Which of the following congenital heart defects is NOT a component of Tetralogy of Fallot?

Accepted Answer

Left ventricular hypertrophy

Question 12

Which heart sound is associated with the closure of the semilunar valves?

Accepted Answer

Dup

Question 13

Which of the following best describes the Frank-Starling Law of the heart?

Accepted Answer

The greater the preload (EDV), the greater the force of contraction and stroke volume.

Question 14

Which of the following would most likely cause a decrease in contractility of the heart?

Accepted Answer

Administration of a beta-blocker

Question 15

A patient is given a drug that blocks muscarinic acetylcholine receptors. What is the expected effect on heart rate?

Accepted Answer

Heart rate will increase due to decreased parasympathetic inhibition.

Question 16

Which of the following best explains why the QRS complex is larger than the P wave on an ECG?

Accepted Answer

The QRS complex represents ventricular depolarization, which involves more muscle mass than atrial depolarization.

Question 17

If the AV bundle is damaged and cannot conduct impulses, what is the expected intrinsic rate of ventricular contraction?

Accepted Answer

30 beats per minute

Question 18

Which of the following is the correct sequence of structures that a cardiac impulse travels through, starting at the SA node?

Accepted Answer

SA node → AV node → AV bundle → Bundle branches → Purkinje fibers

Question 19

A patient with atrial fibrillation is at increased risk for which of the following complications?

Accepted Answer

Stroke due to emboli formation in the atria

Question 20

Which of the following best describes the effect of increasing heart rate to 200 bpm on the cardiac cycle?

Accepted Answer

Diastole is reduced much more than systole, leading to decreased ventricular filling.

Chapter 18: The Heart – Conduction, Rhythm, and Cardiac Function

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