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 to regulate muscle contraction.

Question 2

A patient is diagnosed with a genetic disorder that prevents the formation of intercalated discs. Which muscle tissue would be most affected?

Accepted Answer

Cardiac muscle

Question 3

Which of the following is TRUE regarding the sliding-filament mechanism of muscle contraction?

Accepted Answer

The thin filaments move toward the M line, causing the sarcomere to shorten.

Question 4

Which property of muscle tissue allows it to return to its original length after being stretched?

Accepted Answer

Elasticity

Question 5

During the depolarization stage of an action potential in a muscle fiber, which ion channels open and what is the result?

Accepted Answer

Voltage-gated sodium channels open, causing the membrane potential to become more positive.

Question 6

Which of the following best explains why skeletal muscle fibers are multinucleated?

Accepted Answer

They arise from the fusion of multiple embryonic myoblasts.

Question 7

A drug that blocks acetylcholinesterase would have what effect at the neuromuscular junction?

Accepted Answer

It would cause prolonged stimulation of the muscle fiber by acetylcholine.

Question 8

Which of the following is a function unique to smooth muscle tissue?

Accepted Answer

Propelling substances through hollow organs

Question 9

Which of the following best describes the role of the Na⁺/K⁺ ATPase pump in muscle fibers?

Accepted Answer

It actively transports three sodium ions out and two potassium ions into the cell, maintaining the resting membrane potential.

Question 10

Which of the following structures anchors thin filaments and marks the boundary of a sarcomere?

Accepted Answer

Z-disc

Question 11

A patient presents with muscle weakness and is found to have a defect in the T-tubules of skeletal muscle fibers. Which process would be most directly impaired?

Accepted Answer

Transmission of nerve impulses to the deepest regions of the muscle fiber

Question 12

Which of the following is a regulatory protein found in thin filaments that blocks the active sites on actin at rest?

Accepted Answer

Tropomyosin

Question 13

Which muscle tissue type is characterized by spindle-shaped cells with a single, centrally located nucleus and no striations?

Accepted Answer

Smooth muscle

Question 14

Which of the following best describes the function of intercalated discs in cardiac muscle?

Accepted Answer

They unite cardiac muscle cells for synchronized contraction.

Question 15

Which of the following is the correct sequence of connective tissue layers from innermost to outermost in a skeletal muscle?

Accepted Answer

Endomysium, perimysium, epimysium

Question 16

Which of the following best explains why the resting membrane potential of a muscle fiber is negative?

Accepted Answer

More potassium ions leave the cell than sodium ions enter, making the inside more negative.

Question 17

Which of the following is a function of skeletal muscle tissue but NOT of smooth or cardiac muscle tissue?

Accepted Answer

Maintaining posture

Question 18

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

Accepted Answer

It binds calcium ions and moves tropomyosin away from actin's active sites.

Question 19

A toxin prevents the release of acetylcholine from motor neurons. What is the most immediate effect on skeletal muscle?

Accepted Answer

The muscle will be unable to contract.

Question 20

Which of the following best describes the arrangement of myofilaments in a sarcomere during contraction?

Accepted Answer

The thin filaments slide toward the M line, shortening the sarcomere, while the A band remains unchanged.

Muscle Tissue and Physiology: Structure, Function, and Mechanisms

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