Question 1

Which of the following best describes the role of calcium ions ($$Ca^{2+}) in $$skeletal muscle contraction?

Accepted Answer

They bind to troponin, causing tropomyosin to move and expose active sites on actin.

Question 2

A patient suffers a severe injury that severs the tendon connecting the quadriceps muscle to the tibia. What is the most likely consequence?

Accepted Answer

The muscle will contract, but the tibia will not move.

Question 3

Which of the following is the correct sequence of events at the neuromuscular junction leading to muscle contraction?

Accepted Answer

Acetylcholine is released, binds to receptors, action potential is generated, calcium is released from the sarcoplasmic reticulum.

Question 4

During a muscle contraction, which of the following changes occur in the sarcomere according to the sliding filament theory?

Accepted Answer

The I band shortens, and the A band remains the same.

Question 5

Which of the following best explains why fast-twitch muscle fibers fatigue more quickly than slow-twitch fibers?

Accepted Answer

Fast-twitch fibers have fewer mitochondria and rely primarily on glycolysis, leading to lactic acid buildup.

Question 6

A drug that blocks acetylcholine release at the neuromuscular junction would have which effect?

Accepted Answer

It would prevent muscle contraction.

Question 7

Which of the following is a function of the epimysium in skeletal muscle?

Accepted Answer

It covers the entire muscle and separates it from surrounding tissues.

Question 8

Which of the following best describes the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions change muscle length while tension remains constant; isometric contractions produce tension without changing muscle length.

Question 9

Which of the following best explains why cardiac muscle cannot undergo tetanus?

Accepted Answer

The long refractory period in cardiac muscle prevents sustained contractions.

Question 10

A marathon runner is likely to have a higher proportion of which type of muscle fibers in their leg muscles?

Accepted Answer

Slow-twitch fibers, which are resistant to fatigue.

Question 11

Which of the following is the correct formula for the breakdown of glucose during glycolysis in muscle cells?

Accepted Answer

$$C_6H_{12}O_6$ \rightarrow 2C_3H_4O_3 + 2ATP$$

Question 12

Which muscle is the antagonist to the biceps brachii during elbow flexion?

Accepted Answer

Triceps brachii

Question 13

Which of the following best describes the role of the diaphragm in respiration?

Accepted Answer

It separates the thoracic and abdominopelvic cavities and contracts to increase thoracic volume during inhalation.

Question 14

Which of the following is a real-life example of an isometric contraction?

Accepted Answer

Holding a heavy box steady without moving it.

Question 15

Which of the following best explains why smooth muscle can contract over a wider range of lengths than skeletal muscle?

Accepted Answer

Smooth muscle lacks sarcomeres and has scattered thick and thin filaments.

Question 16

A person with damage to the external intercostal muscles would have difficulty with which process?

Accepted Answer

Inhalation

Question 17

Which of the following best describes the function of the creatine phosphate (CP) system in muscle cells?

Accepted Answer

It provides a rapid source of phosphate to regenerate ATP from ADP during the first few seconds of intense activity.

Question 18

Which of the following is a correct description of the action of the gluteus maximus muscle?

Accepted Answer

Extension, rotation, and abduction at the hip joint

Question 19

Which of the following best explains the physiological reason for increased breathing rate and depth after intense exercise?

Accepted Answer

To repay the oxygen debt and restore normal levels of ATP, creatine phosphate, and glycogen.

Chapter 7: The Muscular System – Essentials of Anatomy & Physiology Study Notes

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