Question 1

Which of the following best describes the primary function of pacemaker cells in cardiac muscle?

Accepted Answer

They spontaneously depolarize to initiate depolarization of the entire heart.

Question 2

What is a key difference between skeletal muscle fibers and cardiac muscle cells regarding stimulation for contraction?

Accepted Answer

Skeletal muscle fibers require nervous system stimulation, but some cardiac muscle cells do not.

Question 3

Which structure in cardiac muscle cells allows for electrical connectivity between myocytes?

Accepted Answer

Gap junctions

Question 4

A patient has a genetic defect that weakens their cardiac desmosomes. Which of the following is the most likely consequence?

Accepted Answer

Myocytes pulling apart during contraction

Question 5

Which of the following equations best represents the process of depolarization in pacemaker cells?

Accepted Answer

$\Delta V = V_{final} - V_{rest}$

Question 6

Which of the following is NOT a characteristic of cardiac muscle cells as seen in the provided microscopic anatomy image?

Accepted Answer

Multiple peripheral nuclei

Question 7

If gap junctions in cardiac muscle were blocked, what would be the most immediate effect on heart function?

Accepted Answer

Electrical signals would not spread efficiently, leading to uncoordinated contractions.

Question 8

Which of the following best explains why pacemaker cells do not require nervous system input to initiate depolarization?

Accepted Answer

They possess unstable resting membrane potentials that gradually depolarize.

Question 9

A researcher is studying the effects of a drug that selectively destroys contractile cells in the heart. Which of the following outcomes is most likely?

Accepted Answer

The heart will lose its ability to contract and pump blood.

Question 10

Which of the following statements about intercalated discs is correct?

Accepted Answer

They contain both gap junctions and desmosomes.

Question 11

A patient with a mutation that prevents the formation of gap junctions in cardiac muscle would most likely experience which of the following?

Accepted Answer

Arrhythmias due to poor electrical conduction

Question 12

Which of the following best describes the role of desmosomes in cardiac muscle?

Accepted Answer

They keep myocytes from pulling apart during contraction.

Question 13

Which of the following is a unique property of cardiac muscle compared to skeletal muscle?

Accepted Answer

Ability to contract without nervous system input

Question 14

If a drug increased the permeability of cardiac muscle cell membranes to sodium ions, what would be the most likely effect on pacemaker activity?

Accepted Answer

Faster depolarization and increased heart rate

Question 15

Which of the following best explains why cardiac muscle cells are resistant to fatigue compared to skeletal muscle fibers?

Accepted Answer

They contain more mitochondria and have a rich blood supply.

Differences Between Skeletal and Cardiac Muscle Physiology

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