Question 1

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

Accepted Answer

It stores and releases $$\mathrm{Ca$$^{2+}$$}$$ ions, which are essential for initiating muscle contraction.

Question 2

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

Accepted Answer

Myasthenia gravis

Question 3

Which connective tissue sheath surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 4

During the sliding filament model of contraction, what happens to the I band and H zone as the muscle contracts?

Accepted Answer

The I band shortens and the H zone disappears.

Question 5

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

Accepted Answer

Action potential arrives at axon terminal → $$\mathrm{Ca$$^{2+}$$}$$ influx → ACh release → ACh binds to receptors → Na$$^+$$ influx → End plate potential

Question 6

Which type of muscle tissue is characterized by being striated, involuntary, and found only in the heart?

Accepted Answer

Cardiac muscle

Question 7

A muscle is contracting but not shortening because the load exceeds the tension the muscle can generate. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 8

Which metabolic pathway provides the fastest means of regenerating ATP during short, high-intensity exercise?

Accepted Answer

Direct phosphorylation of ADP by creatine phosphate

Question 9

Which protein links thin filaments to the sarcolemma and is defective in Duchenne muscular dystrophy?

Accepted Answer

Dystrophin

Question 10

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

Accepted Answer

ATP is no longer produced, so $$\mathrm{Ca$$^{2+}$$}$$ cannot be pumped back into the SR, and cross bridges cannot detach.

Question 11

Which of the following muscle fiber types is most resistant to fatigue and best suited for endurance activities?

Accepted Answer

Slow oxidative fibers

Question 12

A sprinter is using which primary metabolic pathway for ATP production during a 10-second race?

Accepted Answer

Direct phosphorylation by creatine phosphate

Question 13

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

Accepted Answer

Striations

Question 14

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

Accepted Answer

They conduct action potentials deep into the muscle fiber.

Question 15

Which of the following is true regarding the recruitment of motor units during muscle contraction?

Accepted Answer

Smaller motor units are recruited first, followed by larger ones as needed.

Question 16

Which of the following is a unique feature of smooth muscle contraction compared to skeletal muscle contraction?

Accepted Answer

$$\mathrm{Ca$$^{2+}$$}$$ binds to calmodulin instead of troponin.

Question 17

Which of the following best describes the effect of aerobic (endurance) exercise on skeletal muscle?

Accepted Answer

It increases the number of mitochondria, capillaries, and myoglobin content.

Question 18

Which of the following is the correct equation for the direct phosphorylation of ADP by creatine phosphate?

Accepted Answer

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

Question 19

Which of the following is a function of muscle tone?

Accepted Answer

It keeps muscles firm, healthy, and ready to respond.

Question 20

Which of the following best explains why smooth muscle can maintain contraction for long periods with little energy cost?

Accepted Answer

Smooth muscle has slower ATPases and can latch myofilaments together.

Muscles and Muscle Tissue: Structure, Function, and Physiology

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