Question 1

Which of the following best describes the role of the sodium-potassium pump ($$\mathrm{Na^+/K^+}$$ ATPase) in skeletal muscle fibers?

Accepted Answer

It moves three sodium ions out of the cell and two potassium ions in, using ATP hydrolysis to maintain resting membrane potential.

Question 2

A patient presents with muscle weakness and a waddling gait. Genetic testing reveals a mutation in the gene encoding dystrophin. Which of the following best explains the pathophysiology of this condition?

Accepted Answer

Dystrophin mutation disrupts the anchoring of the sarcolemma to the endomysium, causing muscle fiber death and replacement with connective tissue.

Question 3

During the contraction phase of a muscle twitch, which event occurs at the molecular level?

Accepted Answer

Myosin heads bind to actin, forming crossbridges, and perform power strokes to pull thin filaments toward the M line.

Question 4

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

Accepted Answer

ATP is no longer available to pump calcium ions into the sarcoplasmic reticulum, so calcium remains in the cytosol and myosin heads cannot detach from actin.

Question 5

Which of the following is TRUE regarding the sliding-filament mechanism of muscle contraction?

Accepted Answer

Thin filaments slide toward the M line, causing the sarcomere to shorten, but the filaments themselves do not change length.

Question 6

A muscle fiber is stimulated 100 times per second, resulting in a sustained contraction with maximal tension. Which term best describes this phenomenon?

Accepted Answer

Fused (complete) tetanus

Question 7

Which of the following best describes the difference between fast-twitch (Type II) and slow-twitch (Type I) muscle fibers?

Accepted Answer

Type I fibers rely primarily on oxidative catabolism and are more resistant to fatigue.

Question 8

Which of the following best explains why creatine supplementation may improve performance in short, high-intensity activities but not endurance events?

Accepted Answer

Creatine phosphate rapidly regenerates ATP for about 10 seconds, supporting short bursts of activity, but does not contribute significantly to long-duration ATP production.

Question 9

Which of the following is a function of the protein titin in skeletal muscle fibers?

Accepted Answer

It forms the core of the thick filament and provides elasticity, allowing the muscle fiber to spring back after stretching.

Question 10

A patient is exposed to botulinum toxin. Which of the following best describes the effect on skeletal muscle function?

Accepted Answer

The toxin blocks the release of acetylcholine at the neuromuscular junction, preventing muscle contraction and potentially causing respiratory failure.

Question 11

Which of the following best describes the process of excitation-contraction coupling in skeletal muscle fibers?

Accepted Answer

An action potential travels down the T-tubules, triggering the release of calcium ions from the sarcoplasmic reticulum into the cytosol.

Question 12

Which of the following best explains why muscle fatigue occurs during intense exercise?

Accepted Answer

Muscle fatigue results from a combination of factors, including depletion of key metabolites, decreased oxygen availability, and accumulation of chemicals such as ADP and phosphate ions.

Question 13

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

Accepted Answer

It degrades acetylcholine in the synaptic cleft, terminating the signal for muscle contraction.

Question 14

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

Accepted Answer

Maximum tension is produced at an optimal sarcomere length where there is maximal overlap between thick and thin filaments, allowing the greatest number of crossbridges to form.

Question 15

Which of the following is a characteristic of isometric muscle contractions?

Accepted Answer

The muscle generates tension without changing length.

Question 16

Which of the following best describes the effect of endurance training on skeletal muscle fibers?

Accepted Answer

It increases the amount of oxidative enzymes, mitochondria, and blood vessels, enhancing the muscle's resistance to fatigue.

Question 17

Which of the following is the correct sequence of events during the crossbridge cycle in muscle contraction?

Accepted Answer

ATP binds to myosin, myosin detaches from actin, ATP hydrolysis cocks the myosin head, myosin binds to actin, power stroke occurs.

Question 18

Which of the following best explains why delayed-onset muscle soreness (DOMS) occurs after unaccustomed exercise?

Accepted Answer

It is primarily due to minor structural damage to myofilaments, especially from isotonic eccentric contractions.

Muscle Tissue and Physiology: Structured Study Notes for ANP College Students

Study Guide - Practice Questions

Study Guide - Flashcards