Question 1

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

Accepted Answer

It stores and releases $$\mathrm{Ca$$^{2+}$$}$$ ions to regulate muscle contraction.

Question 2

A patient with Duchenne muscular dystrophy (DMD) is likely to have a defect in which protein, and what is the consequence for muscle cells?

Accepted Answer

Dystrophin; muscle cell sarcolemma tears easily, allowing excess $$\mathrm{Ca$$^{2+}$$}$$ entry and muscle degeneration.

Question 3

During the sliding filament model of contraction, which event occurs when the muscle contracts?

Accepted Answer

The I bands shorten, Z discs move closer together, and H zones disappear.

Question 4

Which connective tissue sheath surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 5

What is the primary function of the T tubules in skeletal muscle fibers?

Accepted Answer

To allow electrical nerve transmissions to reach deep into the interior of each muscle fiber.

Question 6

Which of the following is NOT a characteristic shared by all muscle tissue types?

Accepted Answer

Ability to be consciously controlled

Question 7

A patient presents with drooping eyelids and muscle weakness. Laboratory tests reveal antibodies against acetylcholine receptors. What is the most likely diagnosis?

Accepted Answer

Myasthenia gravis

Question 8

Which equation best represents the ionic movement during depolarization of the sarcolemma?

Accepted Answer

$$\mathrm{Na^+}$$ influx \u003e $$\mathrm{K^+}$$ efflux$

Question 9

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

Accepted Answer

It degrades acetylcholine, terminating the signal for muscle contraction.

Question 10

Which of the following is a regulatory protein bound to actin in thin filaments and is essential for muscle contraction?

Accepted Answer

Troponin

Question 11

A muscle fiber is stimulated by a motor neuron. Which sequence correctly describes the events leading to contraction?

Accepted Answer

Action potential arrives → $$\mathrm{Ca$$^{2+}$$}$$ enters axon terminal → Acetylcholine released → Acetylcholine binds to receptors → End plate potential generated

Question 12

Which muscle tissue type is found in the walls of hollow organs and is characterized by being non-striated and involuntary?

Accepted Answer

Smooth muscle

Question 13

Which protein forms the elastic filament in the sarcomere and helps the muscle fiber recoil after stretching?

Accepted Answer

Titin

Question 14

Which of the following is true regarding the arrangement of myofilaments in a sarcomere?

Accepted Answer

Each thick filament is surrounded by six thin filaments in a hexagonal arrangement.

Question 15

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

Accepted Answer

They are formed by the fusion of multiple embryonic myoblasts.

Question 16

Which equation represents the restoration of ionic conditions during repolarization in skeletal muscle fibers?

Accepted Answer

$$\mathrm{Na^+}$$ pumped out, $$\mathrm{K^+}$$ pumped in$

Question 17

Which of the following is a function of skeletal muscle tissue that is critical for maintaining homeostasis?

Accepted Answer

Generating heat as they contract

Question 18

Which scenario best illustrates the application of the RICE method for treating a strained muscle?

Accepted Answer

Rest, Ice, Compression, and Elevation are applied to reduce inflammation and promote healing.

Question 19

Which of the following is true about the neuromuscular junction?

Accepted Answer

It consists of the axon terminal, synaptic cleft, and junctional folds of the sarcolemma.

Muscles and Muscle Tissue: Structure, Function, and Contraction

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