Question 1

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

Accepted Answer

It can contract without nervous system stimulation.

Question 2

Which connective tissue sheath surrounds individual muscle fibers in skeletal muscle?

Accepted Answer

Endomysium

Question 3

During the sliding filament model of contraction, which event directly causes the shortening of the sarcomere?

Accepted Answer

Myosin heads bind to actin and pull thin filaments toward the center of the sarcomere.

Question 4

Which of the following best describes the role of the sarcoplasmic reticulum (SR) in muscle contraction?

Accepted Answer

It stores and releases Ca$$^{2+}$$ ions necessary for contraction.

Question 5

A patient presents with muscle rigidity and inability to relax muscles after death. Which process is most likely responsible for this condition?

Accepted Answer

Lack of ATP required for detachment of myosin heads from actin (rigor mortis)

Question 6

Which structure is the functional unit of a skeletal muscle fiber and is defined as the region between two successive Z discs?

Accepted Answer

Sarcomere

Question 7

What is the primary function of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

To break down acetylcholine and prevent continued muscle fiber contraction

Question 8

Which event occurs first during the generation of an action potential in a muscle fiber?

Accepted Answer

Depolarization

Question 9

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

Accepted Answer

They require multiple nuclei to synthesize large amounts of contractile proteins.

Question 10

Which process is directly responsible for the propagation of an action potential along the sarcolemma?

Accepted Answer

Opening of voltage-gated Na$$^+$$ channels

Question 11

A muscle fiber is stimulated but fails to contract. Which of the following is the most likely cause?

Accepted Answer

Acetylcholine is not released at the neuromuscular junction.

Question 12

Which of the following statements about smooth muscle is correct?

Accepted Answer

It is found in hollow organs and is involuntary.

Question 13

Which protein forms the thick filaments in the sarcomere?

Accepted Answer

Myosin

Question 14

What is the role of troponin in muscle contraction?

Accepted Answer

It binds to Ca$$^{2+}$$ and moves tropomyosin away from actin binding sites.

Question 15

Which event marks the beginning of the latent period in muscle contraction?

Accepted Answer

Time between AP initiation and beginning of contraction

Question 16

Which of the following best describes the function of T tubules in skeletal muscle fibers?

Accepted Answer

They conduct impulses deep into the muscle fiber, ensuring every sarcomere receives the signal.

Question 17

Which of the following is true regarding the energy required for muscle contraction?

Accepted Answer

ATP is required for both the power stroke and the detachment of myosin heads from actin.

Question 18

Which of the following best explains the process of excitation-contraction (E-C) coupling in skeletal muscle?

Accepted Answer

It is the process by which an action potential leads to the release of Ca$$^{2+}$$ and subsequent muscle contraction.

Question 19

Which of the following events occurs during repolarization of the sarcolemma?

Accepted Answer

Na$$^+$$ channels close and K$$^+$$ channels open, restoring resting polarity.

Question 20

A patient is unable to maintain posture and stabilize joints. Which muscle tissue is most likely affected?

Accepted Answer

Skeletal muscle

Muscle Tissue: Structure, Function, and Physiology

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