Question 1

Which connective tissue sheath surrounds an individual muscle fiber?

Accepted Answer

Endomysium

Question 2

A fascicle is best described as:

Accepted Answer

A discrete bundle of muscle cells segregated from the rest of the muscle by connective tissue

Question 3

Which structure is responsible for storing and releasing calcium ions during muscle contraction?

Accepted Answer

Sarcoplasmic reticulum

Question 4

What is the functional unit of a skeletal muscle fiber, responsible for contraction?

Accepted Answer

Sarcomere

Question 5

Which of the following best describes the arrangement of thick and thin filaments in a sarcomere?

Accepted Answer

Thick filaments are located in the A band, while thin filaments extend across the I band and partially into the A band

Question 6

During muscle contraction, which band or zone decreases in width?

Accepted Answer

I band

Question 7

A patient presents with a genetic defect affecting the protein titin. Which sarcomere property is most likely to be compromised?

Accepted Answer

Elasticity and structural integrity

Question 8

Which of the following is true regarding the T tubules in skeletal muscle fibers?

Accepted Answer

They are continuous with the extracellular space and help transmit action potentials deep into the muscle fiber

Question 9

If a muscle fiber is damaged and loses its sarcolemma integrity, which of the following is most likely to occur?

Accepted Answer

Impaired transmission of action potentials into the fiber

Question 10

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

Accepted Answer

They are formed by the fusion of multiple embryonic cells called myoblasts

Question 11

A muscle biopsy reveals a lack of perimysium. Which of the following structures would be most directly affected?

Accepted Answer

Fascicles

Question 12

Which of the following statements about the A band in a sarcomere is correct?

Accepted Answer

It contains the entire length of the thick filaments

Question 13

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

Accepted Answer

Muscle, fascicle, muscle fiber, myofibril, myofilament

Question 14

A researcher is studying the effects of a toxin that disrupts the function of the sarcoplasmic reticulum. Which process would be most directly impaired?

Accepted Answer

Release and reuptake of calcium ions during muscle contraction and relaxation

Question 15

Which of the following best describes the role of myoglobin in skeletal muscle fibers?

Accepted Answer

It binds oxygen for use in aerobic metabolism

Question 16

If a mutation caused the Z discs to be absent in skeletal muscle, which of the following would be most affected?

Accepted Answer

Organization and alignment of sarcomeres

Question 17

Which of the following is true regarding the H zone of a sarcomere?

Accepted Answer

It is the region within the A band that contains only thick filaments

Question 18

A patient with a rare muscle disorder cannot properly transmit action potentials into the interior of muscle fibers. Which structure is most likely defective?

Accepted Answer

T tubules

Question 19

Which of the following best explains why mitochondria are found between myofibrils in skeletal muscle fibers?

Accepted Answer

They supply ATP directly to the contractile proteins during muscle contraction

Question 20

A muscle injury results in the destruction of the epimysium. Which of the following consequences is most likely?

Accepted Answer

Loss of the ability to transmit force from muscle to tendon

Skeletal Muscle Anatomy: Structure and Organization

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