Q: A patient has a heart rate of 75 beats/min and a stroke volume of 70 mL/beat. What is their cardiac output ($$CO$$)?

$$CO = 75 \times 70 = 5250\ \text{mL/min}$$

Question 1

Which of the following best describes the function of the left ventricle in the systemic circuit?

Accepted Answer

It pumps oxygen-rich blood into the aorta and systemic circulation.

Question 2

During the cardiac cycle, which event is responsible for the first heart sound ('lub')?

Accepted Answer

Closing of the atrioventricular (AV) valves

Question 3

A patient presents with a 'creaking' sound heard through a stethoscope and chest pain. Which condition is most likely responsible, and what is the underlying cause?

Accepted Answer

Pericarditis; inflammation of the pericardium causing roughened membrane surfaces

Question 4

Which of the following best explains why the left ventricular wall is thicker than the right ventricular wall?

Accepted Answer

The left ventricle must generate higher pressure to pump blood throughout the entire body.

Question 5

Which of the following correctly traces the flow of blood starting from the left ventricle?

Accepted Answer

Left ventricle → aorta and branches → capillary beds of body tissues → vena cava → right atrium

Question 6

Which of the following statements about the cardiac conduction system is correct?

Accepted Answer

The AV node delays the impulse to ensure the atria empty before the ventricles contract.

Question 7

A patient has a heart rate of 75 beats/min and a stroke volume of 70 mL/beat. What is their cardiac output ($$CO$$)?

Accepted Answer

$$CO = 75 	imes 70 = 5250\ 	ext{mL/min}$$

Question 8

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

Accepted Answer

The greater the stretch of cardiac muscle cells (preload), the greater the force of contraction.

Question 9

Which of the following would most likely increase contractility of the heart?

Accepted Answer

Increased sympathetic stimulation and $$Ca^{2+}$$ influx

Question 10

A patient is experiencing chest pain due to a transient deficiency in blood delivery to the myocardium, but the cells do not die. What is the most likely diagnosis?

Accepted Answer

Angina pectoris

Question 11

Which of the following best explains why cardiac muscle cannot undergo tetanus (sustained contraction)?

Accepted Answer

The absolute refractory period in cardiac muscle is as long as the contraction itself.

Question 12

Which of the following changes would most likely result in an increased end-diastolic volume (EDV)?

Accepted Answer

Increased venous return due to skeletal muscle activity

Question 13

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

$$SV = 120 - 50 = 70\ 	ext{mL}$$

Question 14

Which of the following best describes the effect of acetylcholine (ACh) released by the parasympathetic nervous system on pacemaker cells?

Accepted Answer

Increases $$K^+$$ efflux, hyperpolarizing the cell and decreasing heart rate

Question 15

Which of the following is a likely consequence of a stenotic heart valve?

Accepted Answer

The heart must exert more force to pump blood through the narrowed opening.

Question 16

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

Accepted Answer

They allow ions to pass directly from cell to cell, enabling the heart to function as a syncytium.

Question 17

A patient with a depressed ST segment on their ECG is most likely experiencing which of the following?

Accepted Answer

Cardiac ischemia (reduced blood flow to the heart)

Question 18

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

Accepted Answer

Reduced oxygen delivery to the left ventricle and possible myocardial infarction

Question 19

Which of the following best explains why the heart is resistant to fatigue?

Accepted Answer

Cardiac muscle cells have abundant mitochondria and rely on aerobic respiration.

Anatomy & Physiology: The Heart and Cardiovascular System

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