$$\text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{C}_3\text{H}_6\text{O}_3$$

Question 1

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

Accepted Answer

It stores and releases calcium ions, which trigger muscle contraction.

Question 2

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

Accepted Answer

Tropomyosin shifts, exposing myosin binding sites on actin.

Question 3

A drug that blocks acetylcholine release at the neuromuscular junction would most likely cause which effect?

Accepted Answer

Muscle fibers would not contract due to lack of stimulation.

Question 4

Which connective tissue layer surrounds individual skeletal muscle fibers?

Accepted Answer

Endomysium

Question 5

If acetylcholinesterase (AChE) is absent from the synaptic cleft, what is the most likely outcome?

Accepted Answer

Acetylcholine would remain active, causing prolonged muscle contraction.

Question 6

Which of the following best explains how a muscle returns to its original length after contraction?

Accepted Answer

By gravity, contraction of opposing muscles, and elasticity in tissues.

Question 7

A patient with muscle atrophy in their leg after six weeks in a cast is most likely experiencing which of the following?

Accepted Answer

Decreased muscle fiber size and strength due to lack of stimulation.

Question 8

Which of the following is TRUE regarding the sliding filament theory?

Accepted Answer

Thin filaments slide past thick filaments, causing sarcomeres to shorten.

Question 9

During peak muscle activity, most ATP is produced by which process?

Accepted Answer

Anaerobic metabolism of glucose to lactic acid.

Question 10

Which of the following equations represents the breakdown of glucose during anaerobic metabolism in muscle fibers?

Accepted Answer

$$	ext{C}_6	ext{H}_{12}	ext{O}_6 ightarrow 2	ext{C}_3	ext{H}_6	ext{O}_3$$

Question 11

Which of the following best describes a motor unit?

Accepted Answer

A single motor neuron and all the muscle fibers it innervates.

Question 12

Which phase of a muscle twitch is characterized by calcium binding to troponin and cross-bridge cycling?

Accepted Answer

Contraction phase

Question 13

Which of the following is a consequence of complete tetanus in skeletal muscle?

Accepted Answer

Continuous contraction with no relaxation due to sustained calcium levels.

Question 14

Which of the following best explains rigor mortis after death?

Accepted Answer

Lack of ATP prevents cross-bridge detachment, causing sustained contraction.

Question 15

Which of the following is TRUE regarding muscle hypertrophy?

Accepted Answer

It results from repeated, exhaustive stimulation, increasing muscle fiber size and strength.

Question 16

Which of the following statements about isotonic and isometric contractions is correct?

Accepted Answer

Isotonic contractions change muscle length, while isometric contractions maintain muscle length.

Question 17

Which of the following best describes the relationship between the number of fibers in a motor unit and movement precision?

Accepted Answer

Smaller motor units allow for more precise movements.

Question 18

During muscle recovery after intense activity, the Cori cycle involves which of the following?

Accepted Answer

Conversion of lactate to pyruvate in the liver, then to glucose to replenish muscle glycogen.

Question 19

Which of the following equations represents the oxygen debt required to restore normal muscle conditions after exercise?

Accepted Answer

$$	ext{O}_2 	ext{ required} = 	ext{O}_2 	ext{ consumed during recovery} - 	ext{O}_2 	ext{ consumed at rest}$$

The Muscular System: Structure, Function, and Physiology

Study Guide - Practice Questions