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

A patient is unable to relax their muscles after death, resulting in rigor mortis. Which of the following best explains this phenomenon?

Accepted Answer

ATP is depleted, preventing the detachment of myosin heads from actin.

Question 3

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 4

During the contraction cycle, what event directly triggers the power stroke of the myosin head?

Accepted Answer

Release of ADP and phosphate from the myosin head

Question 5

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 6

A sprinter is running a 100-meter dash. Which type of muscle fibers are primarily being used, and why?

Accepted Answer

Fast fibers, because they generate high force quickly but fatigue rapidly.

Question 7

Which of the following is a function of the connective tissue layer known as the perimysium?

Accepted Answer

It surrounds muscle fascicles and contains blood vessels and nerves.

Question 8

Which of the following best explains why cardiac muscle cells are resistant to fatigue compared to skeletal muscle fibers?

Accepted Answer

They have many mitochondria and rely almost exclusively on aerobic metabolism.

Question 9

A patient is diagnosed with tetanus, a condition caused by the neurotoxin of Clostridium tetani. What is the physiological effect of this toxin on skeletal muscle?

Accepted Answer

It causes sustained, powerful muscle contractions by preventing relaxation.

Question 10

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

Accepted Answer

It breaks down acetylcholine, terminating the signal for muscle contraction.

Question 11

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

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 2\ \mathrm{ADP} + 2\ \mathrm{P_i} + 2\ \mathrm{NAD^+} \rightarrow 2\ \mathrm{C_3H_4O_3} + 2\ \mathrm{ATP} + 2\ \mathrm{NADH} + 2\ \mathrm{H_2O}$$

Question 12

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

Accepted Answer

Smooth muscle can contract even when greatly stretched due to its plasticity.

Question 13

Which of the following best describes the process of muscle hypertrophy?

Accepted Answer

An increase in the diameter of muscle fibers due to heavy training.

Question 14

Which of the following statements about the sliding filament theory is correct?

Accepted Answer

Thin filaments slide toward the M line, causing the sarcomere to shorten.

Question 15

Which of the following best explains why muscle fatigue occurs during intense exercise?

Accepted Answer

Accumulation of lactic acid and hydrogen ions lowers pH, impairing enzyme function.

Question 16

Which of the following is a characteristic of cardiac muscle tissue but NOT skeletal muscle tissue?

Accepted Answer

Presence of intercalated discs for electrical and mechanical connection.

Question 17

Which of the following best describes the effect of thyroid hormones on skeletal muscle?

Accepted Answer

They elevate the rate of energy consumption in resting and active muscles.

Question 18

A muscle is stimulated repeatedly at a frequency greater than 50 times per second, and the muscle does not relax between stimuli. What is this phenomenon called?

Accepted Answer

Complete tetanus

Question 19

Which of the following best describes the role of myoglobin in slow muscle fibers?

Accepted Answer

It binds and stores oxygen, supporting aerobic metabolism.

Question 20

Which of the following is a correct statement about the Cori cycle during muscle recovery?

Accepted Answer

Lactate produced by muscles is transported to the liver, converted to glucose, and returned to muscles.

Muscle Tissue: Structure, Function, and Physiology

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