Question 1

Which of the following best describes the structure and function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

It is a modified smooth endoplasmic reticulum that forms a web-like network around myofibrils and releases $$\mathrm{Ca$$^{2+}$$}$$ ions to trigger muscle contraction.

Question 2

Which of the following is a distinguishing feature of cardiac muscle tissue compared to skeletal and smooth muscle?

Accepted Answer

It is striated, branched, and connected by gap junctions, allowing for synchronized contraction.

Question 3

During the sliding filament mechanism of contraction, which event occurs at the sarcomere level?

Accepted Answer

The I band and H zone both decrease in width as Z-discs are pulled closer together.

Question 4

Which of the following best explains how the resting membrane potential is established in skeletal myocytes?

Accepted Answer

By the active transport of $$\mathrm{Na^+}$$ out and $$\mathrm{K^+}$$ into the cell via sodium-potassium pumps, resulting in a net negative charge inside the cell.

Question 5

A patient presents with muscle weakness. Laboratory tests reveal a defect in the protein titin. Which of the following consequences is most likely?

Accepted Answer

Impaired stabilization and excessive stretching of myofibrils, leading to reduced muscle elasticity.

Question 6

Which of the following correctly matches the muscle type with its primary function and control mechanism?

Accepted Answer

Smooth muscle: involuntary, regulates diameter of blood vessels.

Question 7

Which structural component of a skeletal muscle fiber is responsible for conducting action potentials from the sarcolemma deep into the cell?

Accepted Answer

Transverse tubules (T-tubules)

Question 8

A muscle biopsy shows cells that are short, spindle-shaped, uninucleated, and lack striations. Which muscle type is this?

Accepted Answer

Smooth muscle

Question 9

Which of the following best describes the arrangement of myofilaments in a sarcomere?

Accepted Answer

Thin filaments are anchored to the Z-disc, thick filaments are anchored to the M line, and elastic filaments stabilize the structure.

Question 10

Which of the following is a function of the endomysium in skeletal muscle tissue?

Accepted Answer

It holds individual muscle cells together within the muscle tissue.

Question 11

A researcher blocks all sodium-potassium pumps in a skeletal muscle cell. What is the most immediate effect on the membrane potential?

Accepted Answer

The resting membrane potential will gradually become less negative as $$\mathrm{Na^+}$$ accumulates inside and $$\mathrm{K^+}$$ outside.

Question 12

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

Accepted Answer

They form from the fusion of multiple myoblasts during development, allowing for efficient protein synthesis along their length.

Question 13

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

Accepted Answer

It contains both thick and thin filaments and remains the same length during contraction.

Question 14

A patient has a genetic mutation that prevents the formation of gap junctions in cardiac muscle. Which of the following is the most likely consequence?

Accepted Answer

Impaired electrical conduction between cardiac muscle cells, leading to uncoordinated heart contractions.

Question 15

Which of the following best describes the role of the perimysium in skeletal muscle organization?

Accepted Answer

It collects muscle fibers and endomysium into fascicles, and continues as the tendon.

Question 16

Which of the following is a property shared by all three types of muscle tissue?

Accepted Answer

They all generate muscle tension and are capable of contractility.

Question 17

A muscle cell is stretched to twice its resting length. Which property allows it to return to its original shape after the stretch is removed?

Accepted Answer

Elasticity

Question 18

Which of the following best describes the function of the M line in a sarcomere?

Accepted Answer

It holds thick filaments in place and serves as an anchoring point for elastic filaments.

Question 19

Which of the following scenarios best illustrates the concept of membrane potential in a skeletal myocyte?

Accepted Answer

A difference in electrical charge across the sarcolemma, with the inside of the cell at $$-85 mV $$relative to the outside.

Muscle Tissue I: Structure, Function, and Physiology

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드