Question 1

Which of the following best describes the structure and function of cardiac muscle tissue?

Accepted Answer

Short, branched, uni- or binucleated, involuntary fibers that produce the beating of the heart.

Question 2

Which connective tissue layer surrounds individual muscle fibers within a skeletal muscle?

Accepted Answer

Endomysium

Question 3

What is the primary function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

Storing and releasing calcium ions ($$\mathrm{Ca$$^{2+}$$})$$

Question 4

Which of the following best describes the arrangement of myofilaments in a sarcomere during contraction?

Accepted Answer

Thin filaments slide along thick filaments toward the M line, shortening the sarcomere.

Question 5

Which of the following is a characteristic unique to skeletal muscle cells compared to cardiac and smooth muscle cells?

Accepted Answer

Multinucleation

Question 6

A patient is experiencing muscle weakness due to a defect in the sodium-potassium pump. Which of the following best explains how this defect would affect the resting membrane potential of skeletal myocytes?

Accepted Answer

The resting membrane potential would become more positive due to accumulation of $$\mathrm{Na^+}$$ inside the cell.

Question 7

Which of the following best describes the role of titin in the sarcomere?

Accepted Answer

It stabilizes the myofibril structure and resists excessive stretching.

Question 8

During muscle contraction, which region of the sarcomere shortens the most?

Accepted Answer

I band

Question 9

Which of the following is true regarding the membrane potential of a resting skeletal muscle cell?

Accepted Answer

It is approximately $$-85 mV $$due to the activity of sodium-potassium pumps.

Question 10

A researcher is studying the effects of a toxin that blocks calcium ion channels in the sarcoplasmic reticulum. What would be the most likely effect on skeletal muscle contraction?

Accepted Answer

Decreased release of calcium ions, resulting in weaker or absent contractions.

Question 11

Which of the following best explains why smooth muscle cells can be stretched up to three times their resting length without damage?

Accepted Answer

They possess extensibility and elasticity as key characteristics.

Question 12

Which of the following structures is continuous with the exterior of the cell and filled with extracellular fluid, playing a key role in conducting action potentials into the muscle fiber?

Accepted Answer

Transverse (T) tubules

Question 13

A muscle biopsy reveals cells that are short, spindle-shaped, uninucleated, and lack striations. Which type of muscle tissue is this?

Accepted Answer

Smooth muscle

Question 14

Which of the following best describes the function of the perimysium in skeletal muscle?

Accepted Answer

It collects muscle cells and endomysium into fascicles.

Question 15

Which of the following proteins directly blocks the myosin-binding sites on actin in a relaxed muscle fiber?

Accepted Answer

Tropomyosin

Question 16

A patient with a genetic mutation affecting the structure of Z discs would most likely experience which of the following symptoms?

Accepted Answer

Impaired anchoring of thin filaments and reduced muscle contraction efficiency

Question 17

Which of the following best explains why skeletal muscle fibers are multinucleated?

Accepted Answer

They fuse from multiple myoblasts during development.

Question 18

During the sliding filament mechanism, which of the following occurs?

Accepted Answer

Myosin heads bind to actin and pull thin filaments toward the M line.

Question 19

Which of the following is NOT a function of muscle tissue?

Accepted Answer

Producing hormones

Question 20

Which of the following best describes the electrical gradient across the sarcolemma of a resting skeletal muscle fiber?

Accepted Answer

There is a higher concentration of $$\mathrm{Na^+}$$ outside the cell and a higher concentration of $$\mathrm{K^+}$$ inside.

Muscle Tissue: Structure, Function, and Physiology

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