Question 1

Which of the following best describes the role of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine to terminate stimulation.

Question 2

During muscle contraction, which event directly follows the binding of acetylcholine to receptors on the sarcolemma?

Accepted Answer

Release of calcium ions from the sarcoplasmic reticulum.

Question 3

Which structure anchors thin filaments and marks the boundaries of a sarcomere?

Accepted Answer

Z disc

Question 4

A patient is experiencing muscle fatigue during prolonged exercise. Which of the following is the most likely cause?

Accepted Answer

Excessive accumulation of lactic acid due to anaerobic glycolysis.

Question 5

Which of the following best explains the difference in contraction mechanisms between smooth and skeletal muscle?

Accepted Answer

Smooth muscle requires calmodulin for myosin phosphorylation.

Question 6

Which process is responsible for the rapid electrical signal traveling along the sarcolemma to initiate muscle contraction?

Accepted Answer

Action potential

Question 7

What is the primary function of creatine phosphate in muscle physiology?

Accepted Answer

To provide a rapid source of ATP during short bursts of activity.

Question 8

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

Accepted Answer

It is the region where thick filaments are present.

Question 9

A muscle is contracting eccentrically. Which of the following best describes this type of contraction?

Accepted Answer

The muscle lengthens while generating force.

Question 10

Which equation correctly represents the net ATP yield from glycolysis under anaerobic conditions?

Accepted Answer

$$2 	ext{ ATP}$$

Question 11

A patient with myasthenia gravis has impaired neuromuscular transmission. Which enzyme is most likely targeted by treatment to improve muscle contraction?

Accepted Answer

Acetylcholinesterase

Question 12

Which of the following best describes the role of troponin in skeletal muscle contraction?

Accepted Answer

It binds calcium ions, allowing tropomyosin to move and expose actin binding sites.

Question 13

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

Accepted Answer

Action potential → Calcium release → Cross-bridge formation → Muscle contraction

Question 14

Which factor is most important for muscle endurance during prolonged activity?

Accepted Answer

Aerobic metabolism

Question 15

Which of the following best describes the function of the sarcoplasmic reticulum in muscle cells?

Accepted Answer

It stores and releases calcium ions necessary for muscle contraction.

Question 16

A muscle fiber is stimulated but does not contract because the thick and thin filaments cannot interact. Which protein is most likely malfunctioning?

Accepted Answer

Tropomyosin

Question 17

Which of the following is a correct description of the motor unit?

Accepted Answer

A motor neuron and all the muscle fibers it innervates.

Question 18

Which equation best represents the relationship between force, velocity, and power in muscle contraction?

Accepted Answer

$$	ext{Power} = 	ext{Force} 	imes 	ext{Velocity}$$

Question 19

Which of the following is true about the H zone in a sarcomere?

Accepted Answer

It contains only thick filaments.

Question 20

A patient is unable to relax their muscles after contraction. Which process is most likely impaired?

Accepted Answer

Reuptake of calcium ions into the sarcoplasmic reticulum.

Muscle Structure and Physiology: Mechanisms of Muscle Contraction

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