Question 1

Which structure in the intrinsic cardiac conduction system acts as the primary pacemaker of the heart?

Accepted Answer

Sinoatrial (SA) node

Question 2

During which phase of the cardiac cycle does the atria contract to pump blood into the ventricles?

Accepted Answer

Atrial systole

Question 3

Which of the following best describes the effect of the parasympathetic nervous system on heart rate?

Accepted Answer

It decreases heart rate by releasing acetylcholine.

Question 4

A patient has a heart rate of 100 bpm after their vagus nerve is cut. What was the likely effect of the vagus nerve before it was cut?

Accepted Answer

It decreased the heart rate by approximately 25 bpm.

Question 5

Which event is represented by the QRS complex on an ECG?

Accepted Answer

Ventricular depolarization and atrial repolarization

Question 6

Which of the following would most likely increase stroke volume (SV) according to the diagram?

Accepted Answer

Increased contractility

Question 7

If a patient is experiencing fright and anxiety, which of the following changes would you expect in their autonomic nervous system activity?

Accepted Answer

Increased sympathetic activity and increased heart rate

Question 8

Which chemical regulator increases heart rate and contractility by acting on the heart?

Accepted Answer

Epinephrine

Question 9

What is the effect of thyroxine on the heart?

Accepted Answer

Increases heart rate and enhances the effects of norepinephrine and epinephrine

Question 10

Which of the following best explains why cutting the vagus nerve results in a heart rate of approximately 100 bpm?

Accepted Answer

The intrinsic rate of the SA node is about 100 bpm, and the vagus nerve normally slows it down.

Question 11

A patient has excess extracellular potassium ($$K^+). $$What is the most likely effect on their cardiac function?

Accepted Answer

Abnormal heart rhythms may develop

Question 12

Which of the following is the correct sequence of electrical conduction through the heart?

Accepted Answer

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

Question 13

Which of the following best describes the effect of increased sympathetic activity on the heart?

Accepted Answer

Increases heart rate and force of contraction

Question 14

A patient is given a drug that opens potassium ($$K^+) $$channels in pacemaker cells. What is the expected effect on heart rate?

Accepted Answer

Heart rate will decrease

Question 15

Which interval on the ECG represents the time from the beginning of atrial excitation to the beginning of ventricular excitation?

Accepted Answer

P-R interval

Question 16

Which of the following would most likely decrease end-diastolic volume (EDV)?

Accepted Answer

Decreased ventricular filling time

Question 17

If a patient has increased bloodborne epinephrine and excess $$Ca^{2+}$$, what is the expected effect on stroke volume (SV)?

Accepted Answer

Stroke volume will increase

Question 18

Which of the following best describes the S-T segment on an ECG?

Accepted Answer

Entire ventricular myocardium depolarized

Question 19

A patient is experiencing increased contractility and decreased end-systolic volume (ESV). What is the most likely effect on stroke volume (SV)?

Accepted Answer

Stroke volume will increase

Question 20

Which of the following is a direct effect of acetylcholine on pacemaker cells?

Accepted Answer

Hyperpolarizes pacemaker cells, decreasing heart rate

Cardiac Rhythm and Regulation: ANP Study Notes

Study Guide - Practice Questions