Q: A patient has a heart rate (HR) of 80 beats per minute and a stroke volume (SV) of 65 mL per beat. What is their cardiac output (CO)? Use the formula $$CO = HR \times SV.$$

$$CO = 80 \times 65 = 5200\ \text{mL/min}$$

Question 1

Which of the following best describes the function of the pericardial cavity in the heart?

Accepted Answer

It contains serous fluid that reduces friction between the heart and surrounding structures during contraction.

Question 2

A patient is diagnosed with a defect in the interventricular septum. Which of the following is the most likely consequence?

Accepted Answer

Mixing of oxygen-rich and oxygen-poor blood between the left and right ventricles.

Question 3

Which heart valve prevents backflow of blood from the left ventricle into the left atrium during ventricular systole?

Accepted Answer

Bicuspid (mitral) valve

Question 4

During which phase of the cardiac cycle does the 'lub' sound occur, and what causes it?

Accepted Answer

Ventricular systole; closing of the atrioventricular (AV) valves

Question 5

Which of the following best explains why cardiac muscle cells are highly resistant to fatigue?

Accepted Answer

They have a high volume of mitochondria and rely almost exclusively on aerobic metabolism.

Question 6

A patient has a heart rate (HR) of 80 beats per minute and a stroke volume (SV) of 65 mL per beat. What is their cardiac output (CO)? Use the formula $$CO = HR 	imes SV.$$

Accepted Answer

$$CO = 80 	imes 65 = 5200\ 	ext{mL/min}$$

Question 7

Which structure acts as the heart's natural pacemaker, and what is its typical intrinsic rate?

Accepted Answer

Sinoatrial (SA) node; about 75 beats per minute

Question 8

Which of the following best describes the sequence of electrical conduction through the heart?

Accepted Answer

SA node → AV node → AV bundle (Bundle of His) → bundle branches → Purkinje fibers

Question 9

A patient with aortic valve stenosis will most likely experience which of the following?

Accepted Answer

Increased afterload leading to reduced stroke volume

Question 10

Which of the following changes would most likely increase cardiac output during exercise?

Accepted Answer

Increased sympathetic stimulation, raising both heart rate and stroke volume

Question 11

Which of the following best explains why the refractory period in cardiac muscle is much longer than in skeletal muscle?

Accepted Answer

It prevents tetanic contractions, allowing the heart chambers to refill with blood between beats.

Question 12

A patient is found to have a heart murmur due to a leaky mitral valve. Which of the following is the most likely direct consequence?

Accepted Answer

Backflow of blood from the left ventricle into the left atrium during systole

Question 13

Which of the following best describes the role of the coronary arteries?

Accepted Answer

They supply oxygenated blood to the myocardium.

Question 14

If a patient’s end-diastolic volume (EDV) is 130 mL and their end-systolic volume (ESV) is 60 mL, what is their stroke volume (SV)? Use the formula $$SV = EDV - ESV.$$

Accepted Answer

$$SV = 130 - 60 = 70\ 	ext{mL}$$

Question 15

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

Accepted Answer

Decreased heart rate

Question 16

A patient with chronic hypertension is at risk for which of the following cardiac complications due to increased afterload?

Accepted Answer

Left ventricular hypertrophy

Question 17

Which of the following best explains the significance of the P wave on an electrocardiogram (ECG)?

Accepted Answer

It represents atrial depolarization, which triggers atrial contraction.

Question 18

Which of the following would most likely result from a blockage in the right coronary artery?

Accepted Answer

Ischemia of the right atrium and portions of the right ventricle

Question 19

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

Accepted Answer

The greater the stretch of ventricular muscle (preload), the greater the force of contraction and stroke volume.

Question 20

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

Accepted Answer

Pulmonary congestion and shortness of breath

Anatomy and Physiology of the Heart: Structure, Function, and Cardiac Cycle

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