Question 1

Which phase of the cardiac cycle is characterized by ventricular contraction and rising pressure within the ventricles?

Accepted Answer

Ventricular systole

Question 2

What is the primary function of intercalated discs in cardiac muscle tissue?

Accepted Answer

To connect cardiac muscle cells and prevent separation during contraction

Question 3

During which part of the cardiac cycle do the AV valves close, producing the 'Lubb' sound (S1)?

Accepted Answer

At the start of ventricular systole

Question 4

Which cells in the heart are responsible for generating the action potentials that initiate each heartbeat?

Accepted Answer

Pacemaker cells

Question 5

If the sinoatrial (SA) node fails to function, which structure typically takes over as the pacemaker of the heart?

Accepted Answer

Atrioventricular (AV) node

Question 6

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

Accepted Answer

They allow rapid transmission of action potentials between cells, creating a functional syncytium.

Question 7

A patient’s ECG shows a delay in the transmission of the electrical impulse from the atria to the ventricles. Which structure is most likely responsible for this delay?

Accepted Answer

Atrioventricular (AV) node

Question 8

Calculate the duration of one cardiac cycle if the heart rate is 75 beats per minute. Use the formula $$	ext{Duration} = \frac{60\ 	ext{seconds}}{	ext{beats per minute}}.$$

Accepted Answer

$$0.8\ 	ext{seconds}$$

Question 9

Which event directly triggers the opening of the semilunar (SL) valves during the cardiac cycle?

Accepted Answer

Pressure in ventricles exceeding pressure in arteries

Question 10

What percentage of end-diastolic volume (EDV) is typically ejected from the ventricles as stroke volume during ventricular ejection?

Accepted Answer

60%

Question 11

Which heart sound (S2) is associated with the closing of the semilunar valves?

Accepted Answer

S2

Question 12

A patient has a mutation that affects the function of voltage-gated sodium channels in contractile cells. Which phase of the action potential would be most directly affected?

Accepted Answer

Depolarization

Question 13

Which of the following best explains why cardiac muscle cells have more and larger mitochondria compared to skeletal muscle cells?

Accepted Answer

Cardiac muscle cells require more ATP for continuous contraction.

Question 14

Which of the following is true regarding pacemaker cells in the heart?

Accepted Answer

They use Ca$$^{2+}$$ channels for rapid depolarization.

Question 15

During isovolumetric ventricular contraction, which valves are closed?

Accepted Answer

Both AV and SL valves

Question 16

Which of the following best describes the sequence of events in the cardiac cycle?

Accepted Answer

Atrial systole, ventricular systole, ventricular diastole

Question 17

Which structure rapidly propagates action potentials to trigger ventricular systole and also conducts impulses to papillary muscles?

Accepted Answer

Purkinje fibers

Question 18

If a patient’s ventricles only eject 40% of their end-diastolic volume (EDV) during systole, what is the stroke volume if EDV is 120 mL? Use the formula $$	ext{Stroke Volume} = 	ext{EDV} 	imes 	ext{Ejection Fraction}.$$

Accepted Answer

$$48\ 	ext{mL}$$

Question 19

Which of the following is a direct consequence of the functional syncytium created by gap junctions in cardiac muscle?

Accepted Answer

Action potentials can quickly spread across the heart tissue

Question 20

Which of the following statements about the cardiac cycle is correct?

Accepted Answer

The cardiac cycle includes a rest period after every beat

The Cardiac Cycle and Cardiac Muscle Tissue: Structure, Function, and Electrical Conducting System

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