Question 1

Which structure surrounds individual muscle fibers and plays a key role in transmitting force generated by muscle contraction?

Accepted Answer

Endomysium

Question 2

During muscle contraction, which ion is primarily responsible for triggering the exposure of myosin-binding sites on actin?

Accepted Answer

Calcium ($$\mathrm{Ca$$^{2+}$$})$$

Question 3

What is the main function of acetylcholinesterase (AChE) at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine to terminate the signal.

Question 4

Which of the following best describes the role of the transverse (T) tubules in skeletal muscle fibers?

Accepted Answer

They transmit action potentials deep into the muscle fiber.

Question 5

During the power stroke of muscle contraction, which molecule is hydrolyzed to provide energy?

Accepted Answer

ATP ($$\mathrm{ATP \rightarrow ADP + P_i})$$

Question 6

Which of the following correctly describes the change in the H zone during muscle contraction?

Accepted Answer

It becomes smaller.

Question 7

What is the primary difference between aerobic and anaerobic metabolism in muscle cells?

Accepted Answer

Aerobic metabolism produces more ATP per glucose molecule than anaerobic metabolism.

Question 8

Which protein blocks the myosin-binding sites on actin in a resting muscle fiber?

Accepted Answer

Tropomyosin

Question 9

A patient is experiencing muscle weakness due to a lack of acetylcholine release at the neuromuscular junction. Which step of muscle contraction is most directly affected?

Accepted Answer

Initiation of the action potential on the motor end plate

Question 10

Which of the following best explains why creatine phosphate is important during the initial seconds of intense muscle activity?

Accepted Answer

It rapidly regenerates ATP from ADP.

Question 11

During muscle contraction, what happens to the length of the A band?

Accepted Answer

It remains the same.

Question 12

Which of the following is TRUE regarding the refractory period in muscle physiology?

Accepted Answer

It is the time when the muscle cannot respond to a second stimulus, regardless of strength.

Question 13

Which of the following best describes the difference between skeletal, cardiac, and smooth muscle tissue?

Accepted Answer

Cardiac muscle is striated and has intercalated discs, while smooth muscle is non-striated.

Question 14

Which event directly follows the binding of calcium to troponin during muscle contraction?

Accepted Answer

Exposure of myosin-binding sites on actin

Question 15

A muscle fiber is stimulated repeatedly before it has completely relaxed, resulting in a sustained contraction. What is this phenomenon called?

Accepted Answer

Tetanus

Question 16

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

Accepted Answer

It stores and releases calcium ions.

Question 17

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

Accepted Answer

Release of acetylcholine → Action potential → Calcium binds to troponin → Power stroke

Question 18

Which of the following best explains why the I band shortens during muscle contraction?

Accepted Answer

Actin filaments slide past myosin filaments, overlapping more.

Question 19

Which enzyme is responsible for transferring a phosphate group from creatine phosphate to ADP, forming ATP?

Accepted Answer

Creatine kinase

Question 20

A patient is unable to relax their muscles after contraction. Which of the following is most likely impaired?

Accepted Answer

Breakdown of acetylcholine by acetylcholinesterase

Muscle Tissue Physiology: Structure, Function, and Contraction

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