Question 1

Which of the following best describes the main function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

It stores and releases calcium ions, which are essential for muscle contraction.

Question 2

A patient is unable to voluntarily move their arm muscles but their heart continues to beat normally. Which muscle types are affected and unaffected in this scenario?

Accepted Answer

Skeletal muscle is affected; cardiac muscle is unaffected.

Question 3

Which connective tissue layer directly surrounds a single muscle fiber?

Accepted Answer

Endomysium

Question 4

During the sliding filament theory of muscle contraction, what is the role of calcium ions?

Accepted Answer

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

Question 5

Which of the following is TRUE regarding the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions result in muscle shortening, while isometric contractions do not.

Question 6

Which of the following best explains why muscle fatigue occurs during strenuous exercise?

Accepted Answer

Accumulation of lactic acid and depletion of ATP supply.

Question 7

A muscle fiber is stimulated by a motor neuron. Which event occurs FIRST at the neuromuscular junction?

Accepted Answer

Calcium ions enter the axon terminal.

Question 8

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

Accepted Answer

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

Question 9

Which muscle type is characterized by being striated, involuntary, and containing intercalated discs?

Accepted Answer

Cardiac muscle

Question 10

A muscle fiber is exposed to a rapid series of nerve impulses, resulting in smooth, sustained contractions with no evidence of relaxation. What is this phenomenon called?

Accepted Answer

Fused (complete) tetanus

Question 11

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

Accepted Answer

Pumping blood throughout the body

Question 12

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 13

Which of the following is the correct sequence of events at the neuromuscular junction leading to muscle contraction?

Accepted Answer

Nerve impulse → Calcium entry → Acetylcholine release → Sarcolemma depolarization

Question 14

Which of the following statements about aerobic respiration in muscle cells is CORRECT?

Accepted Answer

It produces about 32 ATP per glucose molecule and requires oxygen.

Question 15

Which of the following best explains why smooth muscle contractions are slower and more sustained compared to skeletal muscle contractions?

Accepted Answer

Smooth muscle lacks striations and has different regulatory proteins.

Question 16

Which of the following is a correct description of the H zone in a sarcomere?

Accepted Answer

It is the region within the A band that lacks actin filaments at rest.

Question 17

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

Accepted Answer

It breaks down acetylcholine, ending muscle contraction.

Question 18

Which of the following is a real-life example of an isometric muscle contraction?

Accepted Answer

Pushing your palms together in front of you without moving them.

Question 19

Which of the following best explains why resistance (isometric) exercise increases muscle size and strength?

Accepted Answer

Individual muscle fibers enlarge (hypertrophy) due to increased tension.

Question 20

Which of the following is the correct formula for the breakdown of ATP to release energy for muscle contraction?

Accepted Answer

$$\mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \mathrm{Energy}$$

The Muscular System: Structure, Function, and Physiology

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