Question 1

Which of the following best describes the role of ATP in muscle contraction and relaxation?

Accepted Answer

ATP is necessary for both the detachment of myosin heads from actin and the reuptake of calcium into the sarcoplasmic reticulum.

Question 2

A patient presents with muscle weakness and is diagnosed with myasthenia gravis. Which of the following best explains the underlying mechanism?

Accepted Answer

Autoimmune attack on acetylcholine receptors at the neuromuscular junction.

Question 3

Which connective tissue layer surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 4

During muscle contraction, which event directly causes the shortening of the sarcomere?

Accepted Answer

Sliding of thick and thin filaments past one another

Question 5

Which of the following is TRUE regarding the difference between isotonic and isometric contractions?

Accepted Answer

Isotonic contractions require actin filaments to move in the sarcomere to lift a load.

Question 6

Which structure in the muscle fiber is responsible for storing and releasing calcium ions during contraction?

Accepted Answer

Sarcoplasmic reticulum

Question 7

A muscle twitch consists of which three phases?

Accepted Answer

Latent period, contraction period, relaxation period

Question 8

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

Accepted Answer

No ATP is available to detach myosin heads from actin, resulting in permanent cross-bridges.

Question 9

Which of the following muscle types is capable of voluntary movement?

Accepted Answer

Skeletal muscle

Question 10

What is the primary function of creatine phosphate in muscle cells?

Accepted Answer

To provide a rapid source of high-energy phosphate for ATP regeneration during brief, intense activity

Question 11

Which protein forms the thick filaments in the sarcomere and has a head that binds to actin?

Accepted Answer

Myosin

Question 12

A muscle cramp is most likely caused by which of the following?

Accepted Answer

Uncontrolled contraction due to dehydration or low levels of potassium or calcium

Question 13

Which of the following equations correctly represents the breakdown of creatine phosphate to regenerate ATP in muscle cells?

Accepted Answer

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

Question 14

Which of the following best describes the function of the triad in a muscle fiber?

Accepted Answer

It allows for the rapid transmission of action potentials and release of calcium for muscle contraction.

Question 15

During sustained strenuous exercise, which metabolic pathway is primarily responsible for maintaining muscle contraction after the first 10 seconds?

Accepted Answer

Aerobic cellular respiration in mitochondria

Question 16

Which of the following statements about muscle fatigue is correct?

Accepted Answer

Muscle fatigue results from the muscle losing its ability to contract after prolonged activity, often due to ion imbalances or accumulation of lactic acid.

Question 17

Which of the following best explains the striated appearance of skeletal muscle fibers?

Accepted Answer

Regular pattern of thick (myosin) and thin (actin) filaments within sarcomeres

Question 18

Which of the following is the correct sequence of events for excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential in motor neuron → acetylcholine release → action potential in muscle fiber → calcium release from sarcoplasmic reticulum

Question 19

Which of the following is a function of muscle tone?

Accepted Answer

To keep muscles healthy and ready to respond to stimulation

Question 20

A patient with delayed onset muscle soreness (DOMS) after intense exercise is most likely experiencing which of the following?

Accepted Answer

Inflammation due to microtearing in the muscle fibers

Muscle System: Structure, Function, and Physiology

Guida di studio - Domande di pratica

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