Question 1

Which of the following best describes what an electrocardiogram (ECG or EKG) measures?

Accepted Answer

The sum of extracellular current flow from large groups of cardiac cells.

Question 2

According to Ohm's Law, which equation correctly relates voltage, current, and resistance as applied to cardiac electrical measurements?

Accepted Answer

$$V = I 	imes R$$

Question 3

During which phase of the cardiac cycle are all heart valves closed and no blood is moving through any of the valves?

Accepted Answer

Isovolumetric contraction

Question 4

What does the P wave on an EKG represent?

Accepted Answer

Atrial depolarization

Question 5

Which event occurs at the QRS complex on an EKG?

Accepted Answer

Ventricular depolarization and atrial repolarization

Question 6

A patient has aortic valve stenosis, causing the aortic valve to close sooner than normal. What is the most likely effect on end-systolic volume (ESV) in the left ventricle?

Accepted Answer

ESV will increase because less blood is ejected.

Question 7

Which of the following best explains why multiple EKG leads (such as 12-lead EKGs) are used in clinical practice?

Accepted Answer

They provide greater sensitivity for detecting specific cardiac events.

Question 8

Which of the following correctly describes the function of the atrioventricular (AV) valves?

Accepted Answer

They prevent backflow into the atria when the ventricles contract.

Question 9

During which phase of the cardiac cycle does the majority of ventricular filling occur?

Accepted Answer

Mid-to-late diastole

Question 10

If the pressure in the left ventricle exceeds the pressure in the aorta, which heart valve opens?

Accepted Answer

Aortic semilunar valve

Question 11

A patient’s EKG shows a prolonged P-R interval. What does this most likely indicate?

Accepted Answer

Delayed conduction between the SA and AV nodes

Question 12

Which of the following is true regarding the opening and closing of heart valves?

Accepted Answer

Valves close when downstream pressure is greater.

Question 13

Which of the following best describes the isovolumetric relaxation phase of the cardiac cycle?

Accepted Answer

Ventricles relax, all valves are closed, and no blood moves.

Question 14

Which of the following is the correct sequence of events in the cardiac cycle?

Accepted Answer

Ventricular filling → isovolumetric contraction → ventricular emptying → isovolumetric relaxation

Question 15

If a patient has a blockage in the right pulmonary artery, which of the following would be directly affected?

Accepted Answer

Blood flow from the right ventricle to the right lung

Question 16

Which of the following best explains why the T wave is positive on a standard EKG?

Accepted Answer

Ventricular repolarization occurs in the opposite direction to depolarization, resulting in a positive deflection.

Question 17

A patient is found to have a mitral valve that does not close properly. Which of the following is a likely consequence?

Accepted Answer

Backflow of blood into the left atrium during ventricular contraction

Question 18

Which of the following best describes the function of the semilunar valves?

Accepted Answer

They prevent backflow into the ventricles when the ventricles relax.

Question 19

If the end-diastolic volume (EDV) is 120 mL and the end-systolic volume (ESV) is 50 mL, what is the stroke volume (SV)? Use the formula $$SV = EDV - ESV.$$

Accepted Answer

$$SV = 70\ \mathrm{mL}$$

Question 20

Which of the following is true regarding the relationship between pressure and valve function in the heart?

Accepted Answer

A valve opens when the pressure upstream is greater than downstream.

Lecture #22

Guida di studio - Domande di pratica

Study guide - Flashcard