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

$$CO = 90 \times 60 = 5400\ \text{mL/min}$$

Question 1

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

Accepted Answer

They prevent the AV valves from inverting during ventricular contraction.

Question 2

During the cardiac cycle, which event directly causes the 'lub' sound heard during auscultation?

Accepted Answer

Closing of the AV valves

Question 3

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

Accepted Answer

$$CO = HR 	imes SV$$

Question 4

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

$$CO = 90 	imes 60 = 5400\ 	ext{mL/min}$$

Question 5

Which of the following correctly matches the electrical event on an ECG with its corresponding mechanical event in the heart?

Accepted Answer

QRS complex: ventricular depolarization

Question 6

What is the primary significance of the plateau phase in the action potential of cardiac contractile cells?

Accepted Answer

It prolongs the refractory period, preventing tetanus.

Question 7

Which of the following best describes the pathway of blood flow through the heart?

Accepted Answer

Right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → pulmonary arteries → lungs → pulmonary veins → left atrium → bicuspid valve → left ventricle → aortic semilunar valve → aorta → body

Question 8

Which of the following chemicals is most likely to cause vasodilation in response to local tissue injury?

Accepted Answer

Histamine

Question 9

If the left ventricle wall is three times thicker than the right, what is the physiological reason for this difference?

Accepted Answer

The left ventricle pumps blood at higher pressure to the systemic circulation.

Question 10

Which of the following best explains the effect of increased sympathetic stimulation on arterioles?

Accepted Answer

It causes vasoconstriction, increasing resistance and blood pressure.

Question 11

Which of the following is a correct sequence for the propagation of an action potential through the intrinsic conduction system of the heart?

Accepted Answer

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

Question 12

Which of the following statements about the baroreceptor reflex is correct?

Accepted Answer

Baroreceptors in the aorta and carotid sinus detect changes in blood pressure and send signals to the medulla to adjust cardiac output and total peripheral resistance.

Question 13

Which of the following is a direct effect of parasympathetic stimulation on the heart?

Accepted Answer

Decreased heart rate via the SA node

Question 14

Which of the following best describes the mechanism of excitation-contraction coupling in cardiac contractile cells?

Accepted Answer

Ca2+ influx from the extracellular fluid triggers additional Ca2+ release from the sarcoplasmic reticulum.

Question 15

Which of the following equations correctly represents the relationship between blood pressure ($$BP$$), cardiac output ($$CO$$), and total peripheral resistance ($$TPR$$)?

Accepted Answer

$$BP = CO 	imes TPR$$

Question 16

Which of the following is a consequence of the plateau phase in the cardiac action potential?

Accepted Answer

It prevents tetanus by prolonging the refractory period.

Question 17

Which of the following would most likely occur if blood pressure drops significantly?

Accepted Answer

Increased sympathetic activity, increased heart rate, and vasoconstriction

Question 18

Which of the following is a correct description of the ejection fraction?

Accepted Answer

The fraction of blood in the ventricle being pumped out during systole

Question 19

Which of the following best describes the effect of nitric oxide (NO) on blood vessels?

Accepted Answer

NO induces vasodilation and decreases blood pressure.

The Cardiovascular System: The Heart and Blood Vessels

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