Question 1

Which of the following best describes the primary function shared by all three types of muscle tissue?

Accepted Answer

To convert chemical energy of ATP into mechanical energy of motion

Question 2

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

Accepted Answer

Autoimmune antibodies block acetylcholine receptors at the neuromuscular junction

Question 3

Which characteristic of muscle tissue allows a muscle to return to its original shape after being stretched?

Accepted Answer

Elasticity

Question 4

During the sliding filament mechanism of muscle contraction, which event directly requires the hydrolysis of ATP?

Accepted Answer

Detachment of the myosin head from actin

Question 5

Which of the following equations best represents the relationship between force (tension), cross-sectional area (A), and muscle fiber type (assuming all other factors are constant)?

Accepted Answer

$$F = k 	imes A$$

Question 6

A marathon runner is likely to have a higher proportion of which type of skeletal muscle fiber?

Accepted Answer

Type I (slow oxidative)

Question 7

Which structural protein connects the Z disc to the M line and provides elasticity and extensibility to the sarcomere?

Accepted Answer

Titin

Question 8

A patient with Duchenne muscular dystrophy has a genetic defect in which protein, leading to progressive muscle weakness?

Accepted Answer

Dystrophin

Question 9

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

Accepted Answer

Lack of ATP prevents detachment of myosin heads from actin

Question 10

Which of the following is true regarding the length-tension relationship in skeletal muscle?

Accepted Answer

Maximum tension is generated at an optimal sarcomere length where actin and myosin overlap maximally

Question 11

Which of the following best describes the role of troponin in muscle contraction?

Accepted Answer

It binds calcium ions, causing a conformational change that exposes myosin-binding sites on actin

Question 12

A muscle is stimulated at a frequency that does not allow complete relaxation between stimuli, resulting in a sustained but wavering contraction. What is this phenomenon called?

Accepted Answer

Unfused (incomplete) tetanus

Question 13

Which of the following is a function of the fascia in the muscular system?

Accepted Answer

It surrounds and holds every organ, blood vessel, bone, nerve fiber, and muscle in place

Question 14

Which of the following best explains why Type IIx (fast glycolytic) muscle fibers fatigue more quickly than Type I (slow oxidative) fibers?

Accepted Answer

Type IIx fibers rely primarily on anaerobic metabolism, which produces less ATP per glucose molecule

Question 15

Which of the following best describes the 'all-or-none' principle of muscle contraction?

Accepted Answer

When a muscle fiber receives a threshold stimulus, it contracts to its full force

Question 16

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

Accepted Answer

Action potential arrives at axon terminal → voltage-gated Ca$$^{2+}$$ channels open → acetylcholine released → acetylcholine binds to receptors on sarcolemma → ligand-gated Na$$^+$$ channels open → muscle action potential generated

Question 17

Which of the following best explains why muscle hypertrophy occurs after resistance training?

Accepted Answer

Enlargement of existing muscle fibers due to repeated mechanical overload

Question 18

Which of the following is a regulatory protein that covers the myosin-binding sites on actin in a resting muscle?

Accepted Answer

Tropomyosin

Question 19

A patient is unable to move a heavy object, even though their muscles are generating tension. Which type of muscle contraction is occurring?

Accepted Answer

Isometric contraction

Question 20

Which of the following best describes the function of satellite cells in skeletal muscle?

Accepted Answer

They aid in muscle repair and can contribute to limited muscle fiber hyperplasia

The Muscular System – Chapter 9 Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard