Question 1

Which of the following muscle types is responsible for voluntary movements such as lifting a dumbbell, as shown in the first image?

Accepted Answer

Skeletal muscle

Question 2

Which connective tissue sheath surrounds an individual muscle fiber?

Accepted Answer

Endomysium

Question 3

What is the primary function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

Storing and releasing calcium ions ($$\mathrm{Ca$$^{2+}$$})$$

Question 4

During muscle contraction, which event directly follows the binding of calcium ions to troponin?

Accepted Answer

Tropomyosin moves, exposing myosin binding sites on actin

Question 5

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 6

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

Accepted Answer

Voluntary control

Question 7

A patient is injected with botulinum toxin (Botox). What is the most direct effect on skeletal muscle contraction?

Accepted Answer

Decreased release of acetylcholine

Question 8

Which of the following best describes the arrangement of thick and thin filaments in a sarcomere?

Accepted Answer

Thin filaments are anchored to Z discs; thick filaments are anchored to M line.

Question 9

Which event initiates the depolarization phase of the muscle action potential?

Accepted Answer

Influx of sodium ions ($$\mathrm{Na^+}) $$through chemically-gated channels

Question 10

Which of the following is a correct sequence of events in excitation-contraction (E-C) coupling?

Accepted Answer

Action potential → T tubule depolarization → Ca$$^{2+}$$ release from SR → Cross bridge formation

Question 11

Which of the following is true regarding the refractory period in a muscle fiber?

Accepted Answer

It is the time during which the muscle fiber cannot be stimulated until repolarization is complete.

Question 12

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

Accepted Answer

ATP is no longer available to detach myosin heads from actin.

Question 13

Which of the following is a function of skeletal muscle tissue?

Accepted Answer

Maintaining posture and body position

Question 14

Which protein directly blocks the myosin binding sites on actin in a relaxed muscle?

Accepted Answer

Tropomyosin

Question 15

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

Accepted Answer

They transmit action potentials deep into the muscle fiber.

Question 16

A patient is bitten by a black widow spider. Which of the following symptoms is most likely due to the venom's effect at the neuromuscular junction?

Accepted Answer

Abdominal cramps due to excessive acetylcholine release

Question 17

Which of the following is the correct order of connective tissue sheaths from outermost to innermost in skeletal muscle?

Accepted Answer

Epimysium, Perimysium, Endomysium

Question 18

Which of the following best describes the sliding filament theory of muscle contraction?

Accepted Answer

Thin filaments slide past thick filaments, shortening the sarcomere.

Question 19

Which of the following is a distinguishing feature of cardiac muscle tissue compared to skeletal muscle tissue?

Accepted Answer

Cardiac muscle is involuntary and striated.

Question 20

Which of the following events occurs first during the cross-bridge cycle?

Accepted Answer

Myosin head attaches to actin, forming a cross bridge.

Muscles and Muscle Tissue: Structure, Function, and Contraction

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