Q: A patient has a stroke volume (SV) of 70 mL and a heart rate (HR) of 80 beats per minute. What is their cardiac output (CO)? Use the formula $$CO = SV \times HR.$$

$$CO = 70 \times 80 = 5600 mL/$$min

Question 1

Which of the following best explains how unidirectional blood flow is maintained through the heart during the cardiac cycle?

Accepted Answer

Through the opening and closing of heart valves in response to pressure changes

Question 2

A patient has a stroke volume (SV) of 70 mL and a heart rate (HR) of 80 beats per minute. What is their cardiac output (CO)? Use the formula $$CO = SV 	imes HR.$$

Accepted Answer

$$CO = 70 	imes 80 = 5600 mL/$$min

Question 3

Which of the following statements about cardiac contractile cells is correct?

Accepted Answer

They are connected by intercalated disks containing gap junctions, allowing force and graded potentials to be transmitted between cells

Question 4

A patient’s ECG shows an abnormally slow heart rate. Which of the following could be a likely cause based on the properties of autorhythmic cells?

Accepted Answer

The AV node is setting the pace instead of the SA node

Question 5

Which of the following best describes the effect of the long refractory period in cardiac contractile cells?

Accepted Answer

It prevents summation of force, ensuring each contraction is followed by relaxation

Question 6

During exercise, sympathetic stimulation increases both heart rate and stroke volume. Which of the following equations correctly represents the relationship between cardiac output, heart rate, and stroke volume?

Accepted Answer

$$CO = HR 	imes SV$$

Question 7

Which of the following is a direct effect of the autonomic nervous system on the heart?

Accepted Answer

It changes the membrane potential and rate of depolarization in autorhythmic cells

Question 8

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)? Use the formula $$SV = EDV - ESV.$$

Accepted Answer

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

Question 9

Which of the following best explains why the SA node is considered the pacemaker of the heart?

Accepted Answer

It has the fastest rate of spontaneous depolarization among autorhythmic cells

Question 10

Which of the following scenarios would most likely result in a conduction block detectable by an ECG?

Accepted Answer

A delay or failure in the transmission of electrical signals from the atria to the ventricles

Question 11

Which of the following is a feature shared by both cardiac and skeletal muscle contraction?

Accepted Answer

Both rely on the influx of calcium ions to initiate contraction

Question 12

A patient’s heart rate is being regulated by the parasympathetic branch of the autonomic nervous system. What is the expected effect on the heart rate?

Accepted Answer

Heart rate will decrease

Question 13

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

Accepted Answer

They allow for the rapid transmission of action potentials and force between contractile cells

Question 14

If a patient’s stroke volume decreases but their heart rate remains constant, what will happen to their cardiac output? Use the formula $$CO = SV 	imes HR.$$

Accepted Answer

Cardiac output will decrease

Question 15

Which of the following is NOT a function of the cardiovascular system as described in the study materials?

Accepted Answer

Generating action potentials in skeletal muscle

Question 16

Which of the following would most likely be observed in a patient with a malfunctioning AV node?

Accepted Answer

The ventricles would contract at a slower rate than the atria

Question 17

Which of the following best explains why ECGs are useful in clinical practice?

Accepted Answer

They allow detection of pathologies affecting heart rate, rhythm, conduction blocks, or coordination

Question 18

Which of the following is true regarding the regulation of stroke volume?

Accepted Answer

It is regulated by intrinsic properties of contractile cells and modulated by the sympathetic branch

Question 19

A patient’s ECG reveals a lack of coordination between atrial and ventricular contractions. Which structure is most likely malfunctioning?

Accepted Answer

AV node

Question 20

Which of the following best describes the relationship between changes in volume and pressure in the heart?

Accepted Answer

Changes in volume induce changes in pressure, which drive blood flow through the circulatory system

The Cardiovascular System: Heart Structure, Function, and Regulation

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