Question 1

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

Accepted Answer

It stores and releases calcium ions necessary for muscle contraction.

Question 2

During the sliding filament theory of muscle contraction, which event occurs immediately after calcium binds to troponin?

Accepted Answer

Tropomyosin moves away from the myosin-binding sites on actin.

Question 3

A patient presents with muscle weakness and is diagnosed with myasthenia gravis. Which of the following best explains the underlying cause of this condition?

Accepted Answer

Loss of acetylcholine receptors at the neuromuscular junction due to an autoimmune response.

Question 4

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

Accepted Answer

It is only found in the heart and is under involuntary control.

Question 5

Which of the following best describes the role of creatine phosphate in muscle contraction?

Accepted Answer

It donates a phosphate group to ADP to rapidly regenerate ATP during the initial seconds of intense activity.

Question 6

A muscle is contracting and generating tension, but its length does not change. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 7

Which of the following statements about the sodium-potassium pump in skeletal muscle fibers is correct?

Accepted Answer

It exports 3 Na$$^+$$ ions and imports 2 K$$^+$$ ions, helping maintain the resting membrane potential.

Question 8

Which of the following best explains why fast fibers (Type IIx) fatigue more quickly than slow fibers (Type I)?

Accepted Answer

Fast fibers rely primarily on anaerobic metabolism and have fewer mitochondria.

Question 9

Which of the following events occurs first during excitation-contraction coupling in skeletal muscle?

Accepted Answer

An action potential arrives at the motor neuron axon terminal.

Question 10

A person is holding a heavy box with their arms flexed but not moving. Which type of muscle contraction is primarily occurring in the biceps brachii?

Accepted Answer

Isometric contraction

Question 11

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

Accepted Answer

It connects thick filaments to Z lines and helps the sarcomere recoil after stretching.

Question 12

Which of the following is true regarding the Cori cycle during muscle recovery?

Accepted Answer

Lactate produced by muscles is transported to the liver, where it is converted to glucose.

Question 13

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

Accepted Answer

ATP is depleted, preventing myosin heads from detaching from actin, resulting in sustained contraction.

Question 14

Which of the following is a function of the muscular system that directly contributes to homeostasis?

Accepted Answer

Maintaining body temperature through heat generation during contraction.

Question 15

Which of the following best describes the difference between concentric and eccentric isotonic contractions?

Accepted Answer

Concentric contractions shorten the muscle, while eccentric contractions lengthen the muscle under tension.

Question 16

Which of the following is the correct sequence of events in the muscle contraction cycle?

Accepted Answer

ATP hydrolysis → cross-bridge formation → power stroke → cross-bridge detachment

Question 17

A muscle fiber is stimulated before it has completely relaxed from a previous stimulus, resulting in a higher level of tension. What is this phenomenon called?

Accepted Answer

Wave summation

Question 18

Which of the following best describes the role of the motor end plate at the neuromuscular junction?

Accepted Answer

It contains acetylcholine receptors that bind neurotransmitter released from the motor neuron.

Question 19

Which of the following is a correct statement about muscle fiber types and their function?

Accepted Answer

Postural muscles contain a higher proportion of slow fibers (Type I) for sustained, anti-fatigue activity.

Question 20

Which of the following best describes the function of a synergist muscle during movement?

Accepted Answer

It assists the agonist by providing additional pull or stabilizing the origin.

Skeletal Muscle Tissue: Structure, Function, and Physiology

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