Question 1

Which of the following best describes the role of the sarcoplasmic reticulum (SR) in skeletal muscle contraction?

Accepted Answer

It stores and releases calcium ions, which are essential for initiating muscle contraction.

Question 2

During the contraction of a skeletal muscle fiber, which of the following changes occur in the sarcomere?

Accepted Answer

The A band remains constant in width, while the I band and H band decrease in size.

Question 3

A patient is experiencing muscle weakness due to a lack of acetylcholinesterase (AChE) at the neuromuscular junction. What is the most likely effect on muscle contraction?

Accepted Answer

Acetylcholine will not be broken down, resulting in prolonged muscle contraction and possible muscle spasms.

Question 4

Which of the following equations correctly represents the net ATP yield from glycolysis per molecule of glucose?

Accepted Answer

$$2 	ext{ ATP}$$

Question 5

Which property of muscle tissue allows it to return to its original length after being stretched?

Accepted Answer

Elasticity

Question 6

A marathon runner relies primarily on which type of muscle fibers for endurance, and what is a key characteristic of these fibers?

Accepted Answer

Slow fibers; they have numerous mitochondria and high myoglobin content.

Question 7

Which of the following best explains why rigor mortis occurs after death?

Accepted Answer

ATP is depleted, preventing the detachment of myosin heads from actin, resulting in sustained contraction.

Question 8

Which of the following is true regarding the length-tension relationship in skeletal muscle fibers?

Accepted Answer

Maximum tension is produced when there is optimal overlap between thick and thin filaments.

Question 9

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

Accepted Answer

Isotonic contractions change muscle length, while isometric contractions do not change muscle length.

Question 10

A patient with a genetic defect in the protein titin would most likely experience which of the following problems?

Accepted Answer

Difficulty returning muscles to their resting length after contraction.

Question 11

Which of the following statements about cardiac muscle tissue is correct?

Accepted Answer

Cardiac muscle cells are connected by intercalated discs, allowing synchronized contraction.

Question 12

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

Accepted Answer

It donates a phosphate group to ADP to rapidly regenerate ATP during the initial phase of contraction.

Question 13

Which of the following is a unique feature of smooth muscle tissue compared to skeletal muscle tissue?

Accepted Answer

Smooth muscle cells lack sarcomeres and are non-striated.

Question 14

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

Accepted Answer

Fast fibers have fewer mitochondria and rely more on anaerobic metabolism.

Question 15

Which of the following best describes the process of wave summation in muscle contraction?

Accepted Answer

Successive stimuli arrive before the relaxation phase has been completed, increasing tension.

Question 16

Which hormone increases both the duration of stimulation and the force of muscle contraction?

Accepted Answer

Epinephrine

Question 17

A person is lifting a heavy box and their muscles are generating tension but not changing length. What type of contraction is occurring?

Accepted Answer

Isometric contraction

Question 18

Which of the following is a function of skeletal muscle that is NOT shared by cardiac or smooth muscle?

Accepted Answer

Producing voluntary movement by pulling on bones

Question 19

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

Accepted Answer

It binds calcium ions, causing tropomyosin to move and expose active sites on actin.

Question 20

Which of the following best explains why the speed of muscle contraction decreases as the load increases?

Accepted Answer

Heavier loads require more time for the muscle to develop enough tension to overcome the resistance.

Muscle Tissue: Structure, Function, and Physiology

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