Question 1

Which structural feature distinguishes cardiac muscle tissue from skeletal muscle tissue?

Accepted Answer

Cardiac muscle fibers contain intercalated discs that facilitate synchronized contraction.

Question 2

Which component of the cardiac conduction system initiates the heartbeat and sets the pace for the heart?

Accepted Answer

Sinoatrial (SA) node

Question 3

During the action potential in cardiac contractile fibers, which phase is characterized by a plateau due to the influx of calcium ions?

Accepted Answer

Phase 2: Plateau phase

Question 4

A patient’s ECG shows an absence of the P wave. Which electrical event is most likely disrupted?

Accepted Answer

Atrial depolarization

Question 5

During ventricular systole, which of the following best describes the pressure and volume changes in the left ventricle?

Accepted Answer

Pressure increases and volume decreases.

Question 6

Which heart sound is associated with the closure of the atrioventricular (AV) valves, and at which point in the ECG does it occur?

Accepted Answer

S1, immediately after the QRS complex

Question 7

If the Purkinje fibers are damaged, which of the following is most likely to occur?

Accepted Answer

Ventricular contraction will be uncoordinated and weaker.

Question 8

Which equation best represents the relationship between stroke volume (SV), end-diastolic volume (EDV), and end-systolic volume (ESV)?

Accepted Answer

$$SV = EDV - ESV$$

Question 9

A patient has a heart rate of 75 beats per minute and a stroke volume of 70 mL. What is their cardiac output?

Accepted Answer

$$5250\ 	ext{mL/min}$$

Question 10

Which of the following best describes the sequence of electrical conduction in the heart?

Accepted Answer

SA node → AV node → Bundle of His → Purkinje fibers

Question 11

During the cardiac cycle, which event occurs immediately after ventricular repolarization?

Accepted Answer

Ventricular relaxation (diastole)

Question 12

Which of the following is a unique functional characteristic of cardiac muscle tissue compared to other muscle types?

Accepted Answer

Ability to contract without neural stimulation (autorhythmicity)

Question 13

Which ECG wave corresponds to ventricular depolarization?

Accepted Answer

QRS complex

Question 14

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

Accepted Answer

Delayed ventricular repolarization

Question 15

Which of the following best describes the relationship between the timing of heart sounds and pressure changes during systole?

Accepted Answer

S1 occurs when ventricular pressure rises above atrial pressure, causing AV valves to close.

Question 16

Which of the following is true regarding the refractory period in cardiac contractile fibers?

Accepted Answer

It prevents tetanus, ensuring rhythmic contractions.

Question 17

During the cardiac cycle, which event is responsible for the second heart sound (S2)?

Accepted Answer

Closure of the semilunar valves

Question 18

Which of the following best explains why the plateau phase is important in the cardiac action potential?

Accepted Answer

It prolongs the refractory period, preventing tetanic contractions.

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)?

Accepted Answer

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

Question 20

Which of the following best describes the effect of increased sympathetic stimulation on the cardiac conduction system?

Accepted Answer

It increases heart rate and force of contraction by stimulating the SA node and contractile fibers.

Cardiac Muscle Tissue and the Cardiac Cycle: Structure, Function, and Electrical Activity

Study Guide - Practice Questions