Question 1

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

Accepted Answer

It stores and releases calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$necessary for muscle contraction.

Question 2

A patient presents with muscle cramps after intense exercise. Which of the following best explains the physiological cause of these cramps?

Accepted Answer

Lack of ATP prevents $$\mathrm{Ca$$^{2+}$$}$$ from being pumped back into the sarcoplasmic reticulum, resulting in sustained contraction.

Question 3

Which connective tissue layer directly surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 4

During the sliding filament theory of muscle contraction, which of the following occurs?

Accepted Answer

Thin filaments slide toward the M line, shortening the sarcomere.

Question 5

Which protein prevents actin-myosin interaction at rest by covering the active sites on actin?

Accepted Answer

Tropomyosin

Question 6

What is the role of acetylcholinesterase (AChE) at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine, terminating the signal for muscle contraction.

Question 7

Which of the following best describes the sequence of events in excitation-contraction coupling?

Accepted Answer

Action potential travels along sarcolemma → T-tubules → SR releases $$\mathrm{Ca$$^{2+}$$}$$ → $$\mathrm{Ca$$^{2+}$$}$$ binds to troponin → Cross-bridge formation

Question 8

Which of the following is true regarding the A band in a sarcomere?

Accepted Answer

It contains the entire length of thick filaments and remains the same width during contraction.

Question 9

A patient is diagnosed with a genetic defect in the titin protein. Which of the following muscle functions is most likely to be affected?

Accepted Answer

Stabilization of thick filaments within the sarcomere

Question 10

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

Accepted Answer

ATP is no longer produced, preventing detachment of myosin heads from actin and $$\mathrm{Ca$$^{2+}$$}$$ reuptake into the SR.

Question 11

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

Accepted Answer

Muscle → Fascicle → Muscle fiber → Myofibril → Sarcomere

Question 12

Which event directly triggers the exposure of active sites on actin during muscle contraction?

Accepted Answer

$$\mathrm{Ca$$^{2+}$$}$$ binding to troponin

Question 13

A drug that blocks voltage-gated sodium channels in the sarcolemma would have which effect on skeletal muscle?

Accepted Answer

It would prevent the initiation and propagation of action potentials, inhibiting muscle contraction.

Question 14

Which of the following best describes the role of ATP in the contraction cycle?

Accepted Answer

ATP binds to myosin, causing detachment from actin and re-cocking of the myosin head.

Question 15

Which of the following is a function unique to skeletal muscle tissue compared to cardiac and smooth muscle?

Accepted Answer

Voluntary control of movement

Question 16

Which structure is formed by the union of the endomysium, perimysium, and epimysium at the end of a muscle?

Accepted Answer

Tendon

Question 17

Which of the following best explains why muscle relaxation is considered a passive process?

Accepted Answer

It occurs when neural stimulation ceases, and cross-bridges are broken without active force generation.

Question 18

Which of the following is true regarding the role of myosatellite cells in skeletal muscle?

Accepted Answer

They function as stem cells to repair damaged muscle fibers.

Question 19

Which of the following best describes the function of the perimysium?

Accepted Answer

It surrounds muscle fascicles and contains blood vessels and nerves.

Question 20

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

Accepted Answer

Exposure of active sites → Formation of cross-bridges → Pivoting of myosin heads → Detachment of cross-bridges → Reactivation of myosin

Muscle Tissue: Structure and Function in Anatomy & Physiology

Guida di studio - Domande di pratica

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