Q: A patient has a heart rate of 80 beats per minute and a stroke volume of 70 mL. What is the cardiac output in liters per minute?

$$CO = 80 \times 70 = 5600 mL/$$min $$= 5.6 L/$$min

Question 1

Which structure in the intrinsic cardiac conduction system is responsible for setting the pace of the heart, and what is its typical rate of depolarization?

Accepted Answer

Sinoatrial (SA) node; 75-100 beats per minute

Question 2

During which phase of the cardiac cycle does ventricular pressure exceed atrial pressure, causing the atrioventricular (AV) valves to close?

Accepted Answer

Isovolumetric contraction

Question 3

Which of the following best describes the effect of sympathetic stimulation on the heart?

Accepted Answer

Increases heart rate and contractility

Question 4

A patient presents with a heart block that delays the transmission of electrical impulses from the atria to the ventricles. Which structure is most likely affected?

Accepted Answer

Atrioventricular (AV) node

Question 5

Which wave on the electrocardiogram (ECG) corresponds to ventricular depolarization?

Accepted Answer

QRS complex

Question 6

If the left bundle branch is blocked, which of the following changes would you expect to see on the ECG?

Accepted Answer

Widened QRS complex

Question 7

Which equation correctly represents cardiac output ($$CO) in $$terms of heart rate ($$HR) $$and stroke volume ($$SV$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 8

A patient with a congenital heart defect has a hole in the interventricular septum. What is the most likely consequence of this defect?

Accepted Answer

Mixing of oxygenated and deoxygenated blood between the ventricles

Question 9

Which of the following best describes the plateau phase of the cardiac muscle action potential?

Accepted Answer

Influx of calcium ions balancing potassium efflux

Question 10

During fetal development, which structure allows blood to bypass the nonfunctional fetal lungs by connecting the right atrium to the left atrium?

Accepted Answer

Foramen ovale

Question 11

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

Accepted Answer

Second heart sound (S2)

Question 12

A patient has a heart rate of 80 beats per minute and a stroke volume of 70 mL. What is the cardiac output in liters per minute?

Accepted Answer

$$CO = 80 	imes 70 = 5600 mL/$$min $$= 5.6 L/$$min

Question 13

Which of the following congenital heart defects results in a right-to-left shunt, causing cyanosis in newborns?

Accepted Answer

Tetralogy of Fallot

Question 14

Which component of the cardiac conduction system delays the electrical impulse to allow the atria to contract before the ventricles?

Accepted Answer

Atrioventricular (AV) node

Question 15

Which of the following best explains why the action potential in cardiac muscle cells has a longer duration than in skeletal muscle cells?

Accepted Answer

Cardiac muscle cells have a plateau phase due to calcium influx

Question 16

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

Accepted Answer

SA node → AV node → Bundle of His → Purkinje fibers

Question 17

Which autonomic nervous system division releases acetylcholine to decrease heart rate?

Accepted Answer

Parasympathetic nervous system

Question 18

A patient with a mutation affecting the Purkinje fibers would most likely experience which of the following?

Accepted Answer

Delayed ventricular contraction

Question 19

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

Accepted Answer

The greater the end-diastolic volume, the greater the force of contraction

Question 20

Which of the following is a direct effect of increased vagal tone on the heart?

Accepted Answer

Decreased heart rate

Heart Physiology: Structure, Function, and Clinical Relevance

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