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 ($$Ca^{2+}) $$necessary for muscle contraction.

Question 2

A patient is unable to perform fine motor skills, such as writing, due to a neurological disorder. Which of the following best explains the underlying anatomical principle?

Accepted Answer

Fine motor skills require motor units with a low innervation ratio (few muscle fibers per neuron).

Question 3

During a 50-meter sprint, which metabolic pathway provides the majority of ATP for muscle contraction?

Accepted Answer

Immediate supply via phosphate transfer (creatine kinase pathway)

Question 4

Which connective tissue sheath surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 5

What is the correct order of structural organization in skeletal muscle from largest to smallest?

Accepted Answer

Muscle belly → Fascicle → Muscle fiber → Myofibril → Myofilament

Question 6

Which protein directly blocks the myosin-binding sites on actin in a relaxed muscle fiber?

Accepted Answer

Tropomyosin

Question 7

A patient with Duchenne muscular dystrophy has a mutation in the gene coding for which protein?

Accepted Answer

Dystrophin

Question 8

Which of the following best describes an isometric muscle contraction?

Accepted Answer

The muscle generates tension but does not change length.

Question 9

What is the primary function of the T-tubules in skeletal muscle fibers?

Accepted Answer

To conduct action potentials deep into the muscle fiber

Question 10

Which of the following events occurs first during skeletal muscle contraction?

Accepted Answer

Release of acetylcholine (ACh) from the motor neuron into the synaptic cleft

Question 11

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

Accepted Answer

ATP is no longer produced, so myosin heads cannot detach from actin.

Question 12

Which of the following is a function of muscle tone?

Accepted Answer

Keeps muscles firm, healthy, and ready to respond

Question 13

Which of the following statements about the sliding filament model of contraction is correct?

Accepted Answer

Thin filaments slide past thick filaments, increasing their overlap without changing their length.

Question 14

Which of the following best describes the role of titin in the sarcomere?

Accepted Answer

It provides elasticity and helps the muscle recoil after stretching.

Question 15

A muscle is attached to two bones. The attachment to the immovable bone is called the:

Accepted Answer

Origin

Question 16

Which of the following is NOT a characteristic of cardiac muscle?

Accepted Answer

Voluntary control

Question 17

During the cross-bridge cycle, what event directly causes the detachment of the myosin head from actin?

Accepted Answer

Binding of ATP to the myosin head

Question 18

Which of the following adaptations is most likely to occur in skeletal muscle after months of aerobic (endurance) exercise?

Accepted Answer

Increased number of mitochondria

Question 19

Which of the following best describes the function of dystrophin in muscle fibers?

Accepted Answer

It links thin filaments to proteins of the sarcolemma, stabilizing the muscle cell membrane.

Question 20

A person is performing a biceps curl. As the biceps brachii shortens to lift the weight, what type of contraction is occurring?

Accepted Answer

Concentric isotonic contraction

Muscles and Muscle Tissue: Structure, Function, and Physiology

Guida di studio - Domande di pratica

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