Question 1

Which of the following tissue types is NOT a component of a skeletal muscle organ?

Accepted Answer

Epithelial tissue

Question 2

Arrange the following structures in order from largest to smallest in the anatomical hierarchy of a skeletal muscle: organ, fascicle, muscle fiber, sarcomere, myofilament.

Accepted Answer

Organ, fascicle, muscle fiber, sarcomere, myofilament

Question 3

During muscle development, myoblasts fuse to form myofibers. If the number of myoblasts at birth is $$N_0$$ and the proliferation rate decreases exponentially with age $$t as$$ $$N(t) = N_0$ e$$^{-kt}$$, what does this imply about the number of new myofibers formed over time?

Accepted Answer

The number of new myofibers formed decreases rapidly as age increases.

Question 4

Where are the nuclei typically located in a mature skeletal muscle fiber?

Accepted Answer

Peripherally, just beneath the sarcolemma

Question 5

Which structure in the sarcomere limits the extent of sarcomere shortening during muscle contraction?

Accepted Answer

Z-line

Question 6

A patient is exposed to a toxin that blocks acetylcholine release at the neuromuscular junction. What immediate effect would this have on skeletal muscle contraction?

Accepted Answer

Muscle contraction would be inhibited due to lack of stimulation.

Question 7

Extracellular $$Ca^{2+} is $$essential for which step in the process of muscle contraction?

Accepted Answer

Release of neurotransmitter from the motor neuron

Question 8

What is the primary function of the sarcoplasmic reticulum in skeletal muscle cells?

Accepted Answer

Storage and regulated release of $$Ca^{2+}$$ for muscle contraction

Question 9

During muscle contraction, which molecule binds to troponin to initiate the exposure of actin binding sites?

Accepted Answer

$$Ca^{2+}$$

Question 10

Which of the following best describes the role of ATP in the cross-bridge cycle of muscle contraction?

Accepted Answer

ATP binds to myosin, causing it to detach from actin and reset for another cycle.

Question 11

A mutation causes the sarcoplasmic reticulum to leak $$Ca^{2+}$$ continuously. What is the most likely effect on muscle function?

Accepted Answer

Muscle would remain in a contracted state (tetany).

Question 12

Which of the following correctly matches the location of mitochondria in a skeletal muscle fiber?

Accepted Answer

Between myofibrils and just beneath the sarcolemma

Question 13

If a drug blocks the reuptake of $$Ca^{2+}$$ into the sarcoplasmic reticulum, what would be the effect on muscle relaxation?

Accepted Answer

Muscle relaxation would be impaired, leading to prolonged contraction.

Question 14

Which of the following steps in muscle contraction directly requires intracellular $$Ca^{2+}$$?

Accepted Answer

Activation of troponin to move tropomyosin off actin binding sites

Question 15

A patient with a genetic defect in tropomyosin cannot properly block actin binding sites. What is the most likely consequence?

Accepted Answer

Muscle contraction would occur even in the absence of $$Ca^{2+}.$$

Question 16

Which of the following best explains why skeletal muscle fibers are multinucleated?

Accepted Answer

Fusion of multiple myoblasts during development

Question 17

If the number of myofibrils per muscle fiber increases, what is the expected effect on muscle strength?

Accepted Answer

Muscle strength increases due to more contractile units.

Question 18

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

Accepted Answer

Action potential in motor neuron → acetylcholine release → muscle fiber depolarization → $$Ca^{2+}$$ release from sarcoplasmic reticulum → contraction

Question 19

Which of the following is a direct effect of $$Ca^{2+}$$ binding to troponin during muscle contraction?

Accepted Answer

Tropomyosin shifts, exposing actin binding sites for myosin

Skeletal Muscle Structure and Function: Study Guide

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