Q: If a person has a stroke volume of 55 mL and a heart rate of 80 beats per minute, what is their cardiac output? Is this a normal value?

Cardiac output = $$55 \times 80 = 4400 mL/$$min, which is slightly below normal.

Question 1

Which of the following best describes the functional difference between the right and left sides of the heart?

Accepted Answer

The right side pumps blood to the lungs (pulmonary circuit), while the left side pumps blood to the rest of the body (systemic circuit).

Question 2

What is the main function of the serous pericardium, and where is it located?

Accepted Answer

It is a double-layered membrane that reduces friction between the heart and surrounding structures, located between the fibrous pericardium and the epicardium.

Question 3

Why can blockage of more than one coronary artery be more dangerous than blockage of a single artery?

Accepted Answer

Multiple blockages prevent collateral circulation, increasing the risk of myocardial infarction.

Question 4

Which structural difference between the right and left ventricles explains why the left ventricle generates higher pressure?

Accepted Answer

The left ventricle has thicker walls and a more circular shape, allowing it to generate greater resistance and pressure.

Question 5

Which structures in the heart prevent backflow of blood, and how do they function?

Accepted Answer

Valves with overlapping flaps close when pressure increases on one side, preventing blood from flowing backward.

Question 6

What is the role of the intercalated discs in cardiac muscle function?

Accepted Answer

They contain gap junctions that allow electrical impulses to pass easily between cells, enabling coordinated contraction.

Question 7

What causes the plateau phase in the contractile cardiac cell action potential, and why is it important?

Accepted Answer

Calcium ion channels open, allowing $$Ca^{2+} to $$enter, which slows repolarization and prolongs contraction.

Question 8

Why is there a delay at the AV node, and what would happen if this delay were too short?

Accepted Answer

The delay allows time for the atria to contract and fill the ventricles before ventricular contraction; if too short, the atria and ventricles would contract simultaneously, reducing cardiac output.

Question 9

If a person has a stroke volume of 55 mL and a heart rate of 80 beats per minute, what is their cardiac output? Is this a normal value?

Accepted Answer

Cardiac output = $$55 	imes 80 = 4400 mL/$$min, which is slightly below normal.

Question 10

Which of the following factors would most likely increase stroke volume?

Accepted Answer

Increased preload, which stretches the ventricular walls and increases contractility.

Question 11

What does a high end-systolic volume (ESV) indicate about cardiac output, and what could cause this?

Accepted Answer

High ESV means less blood is ejected per beat, reducing cardiac output; this could be caused by high blood pressure or decreased contractility.

Question 12

Why does left ventricular failure cause pulmonary congestion and edema?

Accepted Answer

Blood backs up in the pulmonary circuit, increasing pulmonary venous pressure and forcing fluid out of the capillaries into the lungs.

Question 13

A patient’s ECG shows abnormal P waves but normal QRS complexes. What could this indicate?

Accepted Answer

Atrial depolarization is abnormal, possibly due to atrial fibrillation.

Question 14

Which pressure gradient drives blood through the heart and into the great arteries?

Accepted Answer

Pressure generated by ventricular contraction during systole.

Question 15

Which of the following best explains why the QRS complex on an ECG corresponds to ventricular contraction?

Accepted Answer

The QRS complex represents ventricular depolarization, which triggers ventricular contraction.

Question 16

Which of the following would most likely decrease cardiac output?

Accepted Answer

High blood pressure, which increases afterload and reduces stroke volume.

Question 17

Which of the following is a direct result of the Frank-Starling law of the heart?

Accepted Answer

The more the ventricles are stretched during filling, the stronger the contraction.

Question 18

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

Accepted Answer

Reduced blood flow to the right ventricle and portions of the conduction system, potentially causing arrhythmias.

Cardiac Anatomy & Physiology: Structure, Function, and Clinical Concepts

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