Question 1

Which of the following best describes the role of calcium ions ($$Ca^{2+}) in $$skeletal muscle contraction?

Accepted Answer

Calcium ions bind to troponin, causing a conformational change that exposes myosin binding sites on actin.

Question 2

During the cross-bridge cycle in skeletal muscle, what is the immediate consequence of ATP binding to the myosin head?

Accepted Answer

The myosin head detaches from actin.

Question 3

Which of the following equations correctly represents the ATP yield from aerobic respiration of one glucose molecule in skeletal muscle?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + 36ATP$$

Question 4

A patient presents with muscle weakness and is found to have reduced acetylcholine receptor function at the neuromuscular junction. Which condition is most likely?

Accepted Answer

Myasthenia gravis

Question 5

Which property is shared by all three muscle types: skeletal, cardiac, and smooth?

Accepted Answer

Excitability

Question 6

Which of the following best explains why fast-twitch glycolytic fibers fatigue more rapidly than slow-twitch oxidative fibers?

Accepted Answer

Fast-twitch fibers have less myoglobin and rely primarily on glycolysis, which produces less ATP and more lactic acid.

Question 7

Which of the following events occurs first during excitation-contraction coupling in skeletal muscle?

Accepted Answer

Depolarization of the sarcolemma by the end plate potential

Question 8

A muscle is attempting to move a load that exceeds its maximal tension. Which type of contraction is occurring?

Accepted Answer

Isometric contraction

Question 9

Which of the following best describes the length-tension relationship in skeletal muscle?

Accepted Answer

Maximum tension is produced when there is optimal overlap between thick and thin filaments.

Question 10

Which process is responsible for the removal of $$Ca^{2+}$$ from the cytoplasm to allow muscle relaxation?

Accepted Answer

Active transport of $$Ca^{2+}$$ into the sarcoplasmic reticulum by $$Ca^{2+}-$$ATPase

Question 11

Which of the following is a direct effect of acetylcholine binding to its receptor at the motor end plate?

Accepted Answer

Opening of ligand-gated sodium channels

Question 12

Which muscle fiber type is best suited for endurance activities such as marathon running?

Accepted Answer

Type I slow-twitch oxidative fibers

Question 13

Which of the following is a function of satellite cells in skeletal muscle?

Accepted Answer

Regenerate and repair muscle fibers after injury

Question 14

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

Accepted Answer

Skeletal muscle fibers are striated and multinucleated, while smooth muscle fibers are non-striated and have a single nucleus.

Question 15

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

Accepted Answer

Acetylcholine release → binding to receptors → opening of ligand-gated ion channels → end plate potential → action potential propagation

Question 16

Which of the following is a clinical marker for muscle damage, such as in myocardial infarction or rhabdomyolysis?

Accepted Answer

Elevated levels of creatine kinase (CK) in the blood

Question 17

Which of the following best explains the phenomenon of rigor mortis?

Accepted Answer

Lack of ATP prevents detachment of myosin heads from actin, resulting in muscle rigidity.

Question 18

Which of the following is true regarding motor unit recruitment in skeletal muscle?

Accepted Answer

Smaller motor units are recruited first, followed by larger ones for stronger contractions.

Question 19

Which of the following metabolic pathways is primarily used by red, slow-twitch muscle fibers for ATP production?

Accepted Answer

Krebs cycle and oxidative phosphorylation

Question 20

Which of the following best describes the effect of acetylcholinesterase (AChE) at the neuromuscular junction?

Accepted Answer

AChE breaks down acetylcholine, terminating the signal for muscle contraction.

Skeletal Muscle: Structure, Function, and Physiology (ANP 1105A Study Notes)

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