Q: If a patient has an end diastolic volume ($$EDV) of 140 mL$$, an end systolic volume ($$ESV) of 60 mL$$, and a heart rate ($$HR) of 75 $$beats per minute, what is their cardiac output ($$CO$$)? Use the formula $$CO = HR \times (EDV - ESV).$$

$$CO = 75 \times (140 - 60) = 6,000 mL/$$min

Question 1

Which of the following best describes the function of the pulmonary circuit in the cardiovascular system?

Accepted Answer

It transports oxygen-poor blood to the lungs for oxygenation.

Question 2

A patient is diagnosed with pericarditis, resulting in friction between the heart and its surrounding sac. Which specific structure is most likely inflamed, and what is its normal function?

Accepted Answer

The visceral serous pericardium (epicardium); it adheres to the heart and provides lubrication.

Question 3

Which of the following statements about the heart's location and orientation is correct?

Accepted Answer

The base of the heart is attached to large blood vessels and lies more to the right and midline.

Question 4

During ventricular systole, which valves are open and which are closed?

Accepted Answer

AV valves are closed; semilunar valves are open.

Question 5

A blood clot blocks the anterior interventricular artery. Which area of the heart is most at risk for ischemia?

Accepted Answer

Left atrium and anterior walls of both ventricles

Question 6

Which of the following best explains why cardiac muscle cells can contract in a coordinated fashion (as a functional syncytium)?

Accepted Answer

They are connected by gap junctions within intercalated discs, allowing ions to flow directly between cells.

Question 7

A patient has a mutation that impairs the function of the AV node. Which of the following changes would most likely be observed on an ECG?

Accepted Answer

A prolonged PR interval

Question 8

Which of the following equations correctly calculates cardiac output ($$CO) $$using heart rate ($$HR) $$and stroke volume ($$SV$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 9

If a patient has an end diastolic volume ($$EDV) of 140 mL$$, an end systolic volume ($$ESV) of 60 mL$$, and a heart rate ($$HR) of 75 $$beats per minute, what is their cardiac output ($$CO$$)? Use the formula $$CO = HR 	imes (EDV - ESV).$$

Accepted Answer

$$CO = 75 	imes (140 - 60) = 6,000 mL/$$min

Question 10

Which of the following would most likely increase stroke volume ($$SV$$)?

Accepted Answer

Increased contractility of the ventricular myocardium

Question 11

Which of the following best describes the role of extracellular calcium in cardiac muscle contraction?

Accepted Answer

It enters the cell during depolarization and triggers further calcium release from the sarcoplasmic reticulum.

Question 12

During which phase of the cardiac cycle are the ventricles at their maximum volume, and what is this volume called?

Accepted Answer

At the end of ventricular diastole; End Diastolic Volume ($$EDV)$$

Question 13

A patient with aortic valve stenosis has increased resistance to blood flow from the left ventricle. Which factor affecting stroke volume is most directly increased in this condition?

Accepted Answer

Afterload

Question 14

Which of the following best describes the function of papillary muscles and chordae tendineae during ventricular contraction?

Accepted Answer

They prevent the atrioventricular valves from inverting into the atria.

Question 15

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

Accepted Answer

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

Question 16

Which ECG wave corresponds to ventricular depolarization?

Accepted Answer

QRS complex

Question 17

A patient is experiencing a heart rate of 120 beats per minute due to sympathetic nervous system activation. Which of the following is a direct effect of this activation?

Accepted Answer

Increased heart rate and increased contractility

Question 18

Which of the following best explains why the myocardium contains more mitochondria than skeletal muscle?

Accepted Answer

Cardiac muscle requires a continuous supply of ATP for constant contraction.

Question 19

Which vessel returns deoxygenated blood from the heart muscle itself to the right atrium?

Accepted Answer

Coronary sinus

Question 20

Which of the following would most likely occur if the left ventricle's contractility increases, assuming all other variables remain constant?

Accepted Answer

Stroke Volume ($$SV) $$increases

Chapter 18: The Cardiovascular System – The Heart

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