Question 1

Which of the following best describes the role of the sarcoplasmic reticulum (SR) in skeletal muscle contraction?

Accepted Answer

It stores and releases Ca$$^{2+}$$ ions, which are essential for initiating muscle contraction.

Question 2

During a muscle contraction, which event occurs immediately after calcium ions bind to troponin?

Accepted Answer

Tropomyosin shifts to expose the myosin-binding sites on actin.

Question 3

A marathon runner primarily relies on which type of muscle fiber, and why?

Accepted Answer

Slow oxidative (SO) fibers, because they are fatigue-resistant and efficient at aerobic respiration.

Question 4

Which of the following best explains why muscle atrophy occurs after prolonged disuse?

Accepted Answer

There is a reduction in muscle fiber size due to decreased protein synthesis.

Question 5

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

Accepted Answer

They allow rapid transmission of electrical signals and mechanical connection between cells.

Question 6

Which of the following statements about the sliding filament model is correct?

Accepted Answer

During contraction, the I band shortens while the A band remains the same length.

Question 7

A patient is unable to generate enough ATP during strenuous exercise and experiences muscle fatigue. Which metabolic pathway is most likely being used under these conditions?

Accepted Answer

Anaerobic glycolysis, resulting in the production of lactic acid.

Question 8

Which of the following best describes an isometric muscle contraction?

Accepted Answer

The muscle generates tension but does not change in length.

Question 9

In the context of muscle twitch, what occurs during the latent period?

Accepted Answer

The action potential is propagated along the sarcolemma, but no tension is produced yet.

Question 10

Which of the following scenarios best illustrates the concept of wave summation in muscle physiology?

Accepted Answer

A muscle receives repeated stimuli before it can fully relax, resulting in increased tension.

Question 11

Which equation correctly represents the direct phosphorylation of ADP by creatine phosphate in muscle cells?

Accepted Answer

$$\mathrm{Creatine\ phosphate + ADP \rightarrow Creatine + ATP}$$

Question 12

A bodybuilder has a high proportion of fast glycolytic (FG) fibers. Which characteristic is most likely associated with these fibers?

Accepted Answer

They fatigue quickly but generate high force.

Question 13

Which of the following best explains why smooth muscle can sustain contractions for long periods with minimal energy expenditure?

Accepted Answer

Smooth muscle uses a latch-bridge mechanism that maintains tension with low ATP consumption.

Question 14

Which structure is responsible for transmitting the action potential deep into the muscle fiber, ensuring synchronous contraction?

Accepted Answer

T-tubules

Question 15

A muscle fiber is stretched to 150% of its resting length. According to the length-tension relationship, what will happen to its ability to generate tension?

Accepted Answer

It will decrease because there is less overlap between thick and thin filaments.

Question 16

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

Accepted Answer

Presence of intercalated discs containing gap junctions and desmosomes.

Question 17

Which of the following best describes the role of acetylcholine (ACh) at the neuromuscular junction?

Accepted Answer

ACh binds to receptors on the sarcolemma, triggering an action potential in the muscle fiber.

Question 18

Which of the following best explains why lactic acid accumulates in muscles during intense exercise?

Accepted Answer

Oxygen delivery is insufficient, so pyruvic acid is converted to lactic acid during anaerobic glycolysis.

Question 19

Which of the following is true regarding the process of muscle relaxation?

Accepted Answer

Ca$$^{2+}$$ ions are actively pumped back into the sarcoplasmic reticulum, requiring ATP.

Muscle Tissue: Structure, Function, and Physiology

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