Question 1

Which of the following statements best describes the main difference between skeletal, cardiac, and smooth muscle tissue?

Accepted Answer

Skeletal muscle is striated and voluntary, cardiac muscle is striated and involuntary, and smooth muscle is non-striated and involuntary.

Question 2

A patient is experiencing muscle weakness due to a lack of acetylcholine release at the neuromuscular junction. Which step in the muscle contraction process is directly affected?

Accepted Answer

The transmission of the nerve impulse to the muscle cell membrane.

Question 3

Which connective tissue layer surrounds a bundle of muscle fibers (fascicle) in skeletal muscle?

Accepted Answer

Perimysium

Question 4

During the sliding filament theory of muscle contraction, what is the role of calcium ions ($$\mathrm{Ca$$^{2+}$$}$$)?

Accepted Answer

They bind to regulatory proteins on actin, exposing myosin-binding sites.

Question 5

A muscle fiber is unable to return to its resting state after contraction. Which process is most likely impaired?

Accepted Answer

Diffusion of potassium ions ($$\mathrm{K^+}) $$out of the cell and the action of the sodium-potassium pump.

Question 6

Which of the following best explains why muscle contractions become stronger and smoother as the frequency of stimulation increases?

Accepted Answer

Contractions are summed together, leading to unfused or fused tetanus.

Question 7

Which energy pathway provides the fastest way to regenerate ATP during short, intense muscle activity?

Accepted Answer

Direct phosphorylation of ADP by creatine phosphate

Question 8

A marathon runner relies primarily on which ATP regeneration pathway during the majority of the race?

Accepted Answer

Aerobic respiration

Question 9

Which of the following is a characteristic unique to cardiac muscle tissue?

Accepted Answer

It contains intercalated discs that allow rapid communication between cells.

Question 10

A patient is unable to perform isometric contractions. Which activity would they most likely have difficulty with?

Accepted Answer

Pushing their palms together in front of their chest

Question 11

Which of the following best describes the 'all-or-none' law of muscle fiber contraction?

Accepted Answer

A muscle fiber contracts to its fullest extent when stimulated adequately.

Question 12

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

Accepted Answer

Pumping blood throughout the body

Question 13

If the enzyme acetylcholinesterase ($$\mathrm{AChE}) is $$inhibited at the neuromuscular junction, what is the most likely result?

Accepted Answer

Muscle contraction will be prolonged due to continued presence of acetylcholine.

Question 14

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

Accepted Answer

Aerobic respiration is unable to keep up with ATP demand, so anaerobic glycolysis produces lactic acid as a byproduct.

Question 15

Which of the following is true regarding muscle tone?

Accepted Answer

It is a state of continuous partial contraction that keeps muscles firm and ready for action.

Question 16

A muscle cell is unable to store or release calcium ions. Which organelle is most likely malfunctioning?

Accepted Answer

Sarcoplasmic reticulum

Question 17

Which of the following best describes the role of ATP in muscle contraction?

Accepted Answer

ATP provides energy for myosin heads to detach and re-cock for another power stroke.

Question 18

Which of the following scenarios would most likely result in muscle fatigue?

Accepted Answer

Prolonged, strenuous activity leading to ion imbalances and lactic acid accumulation

Question 19

Which of the following is a direct result of aerobic (endurance) exercise on skeletal muscle?

Accepted Answer

Muscles become more resistant to fatigue and metabolism becomes more efficient.

Question 20

A muscle is stimulated so rapidly that no evidence of relaxation is seen and contractions are smooth and sustained. What is this state called?

Accepted Answer

Fused (complete) tetanus

The Muscular System: Structure, Function, and Physiology

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