Question 1

Which of the following statements best describes the 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 ATP production. Which process would be directly affected first?

Accepted Answer

Formation of myosin cross bridges during contraction

Question 3

Which connective tissue wrapping surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 4

During the sliding filament mechanism of muscle contraction, which event occurs immediately after myosin binds to actin?

Accepted Answer

Myosin head pivots, pulling the actin filament toward the center of the sarcomere

Question 5

Which of the following best explains why rigor mortis occurs after death?

Accepted Answer

Calcium ions leak into the sarcoplasm, allowing myosin cross bridges to form, but lack of ATP prevents their detachment

Question 6

Which equation correctly represents the regeneration of ATP from creatine phosphate in muscle cells?

Accepted Answer

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

Question 7

A muscle fiber is stimulated so rapidly that it does not have time to relax between stimuli, resulting in a sustained contraction. What is this phenomenon called?

Accepted Answer

Complete tetanus

Question 8

Which of the following is the functional unit of skeletal muscle?

Accepted Answer

Sarcomere

Question 9

Which protein is primarily responsible for the thick filaments in a sarcomere?

Accepted Answer

Myosin

Question 10

A patient with a genetic defect in the protein dystrophin would most likely experience which of the following?

Accepted Answer

Weakness due to inability to anchor thin filaments to the sarcolemma

Question 11

Which of the following best describes the role of calcium ions ($$\mathrm{Ca}^{2+}) in $$muscle contraction?

Accepted Answer

Calcium ions bind to troponin, causing tropomyosin to move and expose myosin-binding sites on actin

Question 12

Which of the following is true regarding isometric muscle contractions?

Accepted Answer

The muscle generates tension but does not change length

Question 13

Which structure conducts electrical impulses deep into the muscle fiber, ensuring simultaneous contraction throughout the cell?

Accepted Answer

T tubules

Question 14

Which of the following best explains the 'staircase effect' (treppe) observed in muscle contraction?

Accepted Answer

Repeated stimulation of muscle fibers of the same strength leads to progressively stronger contractions due to increased $$\mathrm{Ca}^{2+}$$ availability

Question 15

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

Accepted Answer

Ability to contract without nervous stimulation

Question 16

Which process is responsible for restoring the resting ionic conditions of the sarcolemma after an action potential?

Accepted Answer

Activity of the sodium-potassium pump ($$\mathrm{Na}^+/\mathrm{K}^+$$ pump)

Question 17

A marathon runner experiences muscle fatigue during the final stretch of a race. Which of the following is most likely contributing to this fatigue?

Accepted Answer

Accumulation of lactic acid and inability to regenerate ATP fast enough

Question 18

Which of the following best describes the role of acetylcholinesterase (AChE) at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine, preventing continued muscle contraction

Question 19

Which of the following equations represents the hydrolysis of ATP during muscle contraction?

Accepted Answer

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{Pi} + 	ext{energy}$$

Question 20

Which of the following is true regarding motor units in skeletal muscle?

Accepted Answer

Muscles responsible for fine movements have small motor units

Muscle Tissue: Structure, Function, and Physiology

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