Question 1

Which connective tissue layer surrounds individual muscle fibers and plays a crucial role in transmitting force generated by muscle contraction?

Accepted Answer

Endomysium

Question 2

A patient is diagnosed with muscle atrophy due to prolonged immobilization. Which cellular structure is most directly affected, leading to a decrease in muscle fiber diameter?

Accepted Answer

Myofibrils

Question 3

During a muscle contraction, calcium ions are released from which organelle, triggering the interaction between actin and myosin?

Accepted Answer

Sarcoplasmic reticulum

Question 4

Which protein forms the thick filaments in a sarcomere and is responsible for the power stroke during muscle contraction?

Accepted Answer

Myosin

Question 5

A sprinter relies primarily on which type of muscle fibers for explosive, short-duration activity?

Accepted Answer

Fast fibers

Question 6

Which of the following best describes the role of the Z-lines in a sarcomere?

Accepted Answer

They separate adjacent sarcomeres.

Question 7

If a muscle is stimulated repeatedly without sufficient time to relax, which phenomenon occurs, resulting in a sustained contraction?

Accepted Answer

Complete tetanus

Question 8

Which metabolic pathway is primarily used by slow muscle fibers to generate ATP during prolonged, low-intensity exercise?

Accepted Answer

Aerobic metabolism

Question 9

A bodybuilder experiences muscle hypertrophy after months of resistance training. Which process best explains this adaptation?

Accepted Answer

Increase in the size of existing muscle fibers

Question 10

Which structure is responsible for transmitting the action potential deep into the muscle fiber, ensuring uniform contraction?

Accepted Answer

T-tubules

Question 11

During isometric contraction, which of the following is true?

Accepted Answer

Muscle length remains constant while tension increases.

Question 12

Which of the following best describes the function of troponin in muscle contraction?

Accepted Answer

It binds calcium ions, causing a conformational change that exposes myosin binding sites on actin.

Question 13

A marathon runner's muscles are primarily composed of which type of fibers, and what is their main energy source?

Accepted Answer

Slow fibers; aerobic metabolism

Question 14

Which event directly triggers the power stroke in the cross-bridge cycle of muscle contraction?

Accepted Answer

Release of ADP and Pi from myosin

Question 15

Which of the following equations correctly represents the breakdown of glucose during glycolysis?

Accepted Answer

$$ \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 2\mathrm{NAD}^+ + 2\mathrm{ADP} + 2\mathrm{P}_i \rightarrow 2\mathrm{C}_3\mathrm{H}_4\mathrm{O}_3 + 2\mathrm{NADH} + 2\mathrm{ATP} + 2\mathrm{H}_2\mathrm{O} $$

Question 16

Which of the following best describes concentric contraction?

Accepted Answer

The muscle shortens while generating force.

Question 17

Which band in the sarcomere contains only thick filaments and is central to the contraction process?

Accepted Answer

H-band

Question 18

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

Accepted Answer

Action potential travels along sarcolemma → calcium released from sarcoplasmic reticulum → troponin binds calcium → myosin binds actin

Question 19

Which structure is the functional unit of a muscle fiber, responsible for contraction?

Accepted Answer

Sarcomere

Question 20

A patient with a genetic mutation affecting tropomyosin would most likely experience which of the following symptoms?

Accepted Answer

Uncontrolled muscle contractions due to constant exposure of myosin binding sites

Muscle Structure and Physiology: Key Terms and Concepts

Guida di studio - Domande di pratica

Study guide - Flashcard