Q: A patient has a heart rate of 90 beats/min and a stroke volume of 60 mL/beat. What is their cardiac output?

$$CO = 90 \times 60 = 5400\,mL/min$$

Question 1

Which layer of the heart wall is responsible for the contractile function of the heart and contains spiral bundles of cardiac muscle cells?

Accepted Answer

Myocardium

Question 2

A patient presents with chest pain that radiates to the left arm and jaw. Which condition is most likely if the pain is due to a prolonged coronary blockage?

Accepted Answer

Myocardial infarction

Question 3

Which of the following best describes the function of the chordae tendineae?

Accepted Answer

They prevent the AV valve cusps from everting into the atria during ventricular contraction.

Question 4

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

Accepted Answer

Ventricular systole

Question 5

Which equation correctly represents cardiac output (CO)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 6

If a patient has an end diastolic volume (EDV) of 120 mL and an end systolic volume (ESV) of 50 mL, what is their stroke volume (SV)?

Accepted Answer

$$SV = 120\,mL - 50\,mL = 70\,mL$$

Question 7

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

Accepted Answer

Reduced stroke volume (SV)

Question 8

Which structure is known as the pacemaker of the heart?

Accepted Answer

Sinoatrial (SA) node

Question 9

Which of the following best explains why the left ventricle has a thicker myocardium than the right ventricle?

Accepted Answer

It pumps blood into the systemic circuit, which has higher resistance.

Question 10

Which of the following is a positive inotropic agent that increases contractility of the heart?

Accepted Answer

Thyroxine

Question 11

A patient has a heart rate of 90 beats/min and a stroke volume of 60 mL/beat. What is their cardiac output?

Accepted Answer

$$CO = 90 	imes 60 = 5400\,mL/min$$

Question 12

Which of the following best describes the function of gap junctions in cardiac muscle?

Accepted Answer

They allow ions to pass between cells, enabling coordinated contraction.

Question 13

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

Accepted Answer

Ventricular depolarization

Question 14

Which of the following would most likely result from a defective SA node?

Accepted Answer

Junctional rhythm

Question 15

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

Accepted Answer

The greater the stretch of cardiac muscle cells before contraction, the greater the force of contraction.

Question 16

Which of the following is true regarding the pulmonary circuit?

Accepted Answer

It carries blood to and from the lungs.

Question 17

Which of the following would most likely cause a heart murmur?

Accepted Answer

Abnormal function of a heart valve

Question 18

Which of the following best describes the effect of acetylcholine on the heart?

Accepted Answer

It decreases heart rate by opening K+ channels.

Question 19

Which of the following is the correct sequence of excitation in the intrinsic cardiac conduction system?

Accepted Answer

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

Question 20

A patient with persistent high blood pressure is at risk for which of the following cardiac conditions due to increased afterload?

Accepted Answer

Congestive heart failure

The Cardiovascular System: The Heart – Structure, Function, and Physiology

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