$$CO = 80 \times 65 = 5200\,mL/min$$

Question 1

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

Accepted Answer

Mitral (bicuspid) valve

Question 2

During which phase of the cardiac cycle are all heart valves closed and ventricular pressure is rising, but no blood is ejected?

Accepted Answer

Isovolumetric contraction

Question 3

A healthy adult has an end-diastolic volume (EDV) of 120 mL and an end-systolic volume (ESV) of 50 mL. What is the stroke volume (SV)?

$$SV = EDV - ESV$$

Accepted Answer

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

Question 4

Which of the following best describes the function of the SA node in the heart?

Accepted Answer

It generates and conducts electrical impulses to set the heart rate.

Question 5

If a patient has a heart rate of 80 beats per minute and a stroke volume of 65 mL, what is their cardiac output?

$$CO = HR 	imes SV$$

Accepted Answer

$$CO = 80 	imes 65 = 5200\,mL/min$$

Question 6

Which phase of the cardiac cycle is associated with the 'lub' sound heard during auscultation?

Accepted Answer

Isovolumetric contraction

Question 7

Which of the following factors would most likely increase heart rate?

Accepted Answer

Release of epinephrine and norepinephrine

Question 8

What does the QRS complex on an ECG represent?

Accepted Answer

Ventricular depolarization

Question 9

Which of the following is a life-threatening cardiac dysrhythmia that requires immediate defibrillation?

Accepted Answer

Ventricular fibrillation

Question 10

A patient’s ECG shows a prolonged P-R interval. What is the most likely cause?

Accepted Answer

Heart block at the AV node

Question 11

Which of the following best explains why the T wave may become inverted in some pathologies?

Accepted Answer

Abnormal ventricular repolarization

Question 12

Which of the following is true regarding the plateau phase of the cardiac contractile cell action potential?

Accepted Answer

It is unique to cardiac muscle and prolongs the refractory period.

Question 13

Which of the following would most likely decrease stroke volume?

Accepted Answer

Decreased contractility

Question 14

Which chamber of the heart receives oxygen-poor blood from the body?

Accepted Answer

Right atrium

Question 15

Which of the following best describes the function of the AV valves during ventricular systole?

Accepted Answer

They close to prevent backflow into the atria.

Question 16

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

Accepted Answer

SA node → AV node → Bundle branches → Purkinje fibers

Question 17

Which of the following would most likely be seen in a trained athlete compared to an untrained individual?

Accepted Answer

Lower resting heart rate

Question 18

Which interval on the ECG represents the time it takes for depolarization to spread from the SA node through the atria to the ventricles?

Accepted Answer

P-R interval

Question 19

Which of the following is true regarding ventricular ejection?

Accepted Answer

AV valves are closed and SL valves are open.

Question 20

A patient presents with a widened QRS complex on their ECG. Which of the following is the most likely explanation?

Accepted Answer

Delayed conduction through the bundle branches

The Cardiovascular System: The Heart – Structure, Function, and Cardiac Cycle

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