Question 1

Which wave on the ECG corresponds to atrial depolarization, and what mechanical event does it precede?

Accepted Answer

P wave; it precedes atrial contraction

Question 2

During which phase of the cardiac cycle are both the AV and semilunar valves closed, and what is the consequence for ventricular volume?

Accepted Answer

Isovolumetric contraction; ventricular volume remains constant

Question 3

What causes the mitral valve to open during the cardiac cycle?

Accepted Answer

Left atrial pressure exceeds left ventricular pressure

Question 4

A patient has an end-diastolic volume (EDV) of 130 mL and an end-systolic volume (ESV) of 55 mL. What is the stroke volume (SV)?

$$SV = EDV - ESV$$

Accepted Answer

$$SV = 130\ \mathrm{mL} - 55\ \mathrm{mL} = 75\ \mathrm{mL}$$

Question 5

Which event is responsible for the first heart sound ('lub') heard with a stethoscope?

Accepted Answer

Closure of the AV valves

Question 6

Why does blood flow from the left atrium to the left ventricle during ventricular filling?

Accepted Answer

Because left atrial pressure is greater than left ventricular pressure

Question 7

Which of the following best explains why the ECG cannot directly measure the amount of blood ejected by the heart?

Accepted Answer

The ECG records electrical activity, not mechanical events or blood volume

Question 8

During which phase of the cardiac cycle does ventricular pressure rise rapidly while ventricular volume remains unchanged?

Accepted Answer

Isovolumetric contraction

Question 9

If a patient’s ventricular pressure exceeds aortic pressure, what happens to the aortic valve?

Accepted Answer

It opens, allowing blood to flow into the aorta

Question 10

Which of the following statements about the QRS complex is correct?

Accepted Answer

It represents ventricular depolarization, which precedes ventricular contraction

Question 11

A patient’s ECG shows a prolonged PR interval. What does this most likely indicate?

Accepted Answer

Delayed conduction through the AV node

Question 12

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

Accepted Answer

Valves open and close passively in response to pressure gradients

Question 13

During isovolumetric relaxation, what is the state of the heart valves and ventricular volume?

Accepted Answer

Both AV and semilunar valves are closed; ventricular volume is constant

Question 14

Which of the following best describes the relationship between the T wave and ventricular events?

Accepted Answer

The T wave represents ventricular repolarization, which precedes ventricular relaxation

Question 15

If both the AV and semilunar valves are closed, what happens to blood flow in the ventricle?

Accepted Answer

No blood enters or leaves the ventricle

Question 16

Which of the following is a common misconception about the ECG?

Accepted Answer

The ECG measures how strongly the heart contracts

Question 17

Which of the following best explains why ventricular contraction does not always mean blood is leaving the ventricle?

Accepted Answer

During isovolumetric contraction, both valves are closed so volume does not change

Question 18

Which of the following is the correct formula for calculating stroke volume?

Accepted Answer

$$SV = EDV - ESV$$

Question 19

A patient’s heart sound reveals a murmur between the 'lub' and 'dub'. What does this most likely indicate?

Accepted Answer

A valve is not opening or closing properly, causing abnormal blood flow

Question 20

Which of the following statements about ventricular filling is correct?

Accepted Answer

Most ventricular filling occurs passively before atrial contraction

Cardiac Physiology: Electrical Activity, Pressure Changes, and Heart Valves

스터디 가이드 - 연습 문제