Q: Which of the following best explains why muscle fatigue occurs during peak activity levels?

Anaerobic glycolysis produces excess lactate and H\textsuperscript{+}, lowering pH and causing fatigue.

Question 1

Which of the following best explains why muscle fatigue occurs during peak activity levels?

Accepted Answer

Anaerobic glycolysis produces excess lactate and H	extsuperscript{+}, lowering pH and causing fatigue.

Question 2

During moderate activity, which metabolic pathway is primarily responsible for ATP production in skeletal muscle fibers?

Accepted Answer

Aerobic metabolism in the mitochondria

Question 3

Which of the following equations correctly represents the conversion of creatine phosphate (CP) to ATP in muscle fibers?

Accepted Answer

$$\mathrm{CP} + \mathrm{ADP} \rightarrow \mathrm{C} + \mathrm{ATP}$$

Question 4

A marathon runner is able to sustain muscle contraction for hours, while a sprinter fatigues quickly. Which muscle fiber type predominates in the marathon runner’s leg muscles?

Accepted Answer

Slow fibers

Question 5

Which of the following is a major source of ATP during the first 15 seconds of intense muscle activity?

Accepted Answer

Breakdown of creatine phosphate

Question 6

What is the primary fate of lactate produced by skeletal muscle during peak activity, according to the Cori cycle?

Accepted Answer

It diffuses into the blood and is converted to glucose in the liver.

Question 7

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

Accepted Answer

Increase in muscle size due to repeated exhaustive stimulation

Question 8

Which of the following is a direct effect of decreased pH in muscle fibers during intense exercise?

Accepted Answer

Decreased enzyme activity and reduced calcium/troponin binding

Question 9

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

Accepted Answer

ATP is depleted, preventing detachment of myosin cross-bridges from actin.

Question 10

Which of the following statements about fast muscle fibers is correct?

Accepted Answer

They fatigue rapidly and rely primarily on anaerobic metabolism.

Question 11

A patient presents with progressive muscular weakness due to loss of acetylcholine receptors at the neuromuscular junction. Which condition is most likely?

Accepted Answer

Myasthenia gravis

Question 12

Which of the following best describes oxygen debt (EPOC) after intense exercise?

Accepted Answer

The amount of oxygen required to restore ATP, creatine phosphate, and glycogen levels in muscle and convert lactate to glucose in the liver.

Question 13

Which of the following is a characteristic of slow muscle fibers?

Accepted Answer

Small diameter, many mitochondria, high myoglobin

Question 14

Which of the following equations represents the net ATP yield from aerobic metabolism of one pyruvate molecule?

Accepted Answer

$$1\ \mathrm{pyruvate} + \mathrm{O}_2 \rightarrow 15\ \mathrm{ATP} + \mathrm{CO}_2 + \mathrm{H}_2\mathrm{O}$$

Question 15

A person’s leg gives way after a cast is removed following six weeks of immobilization. What is the most likely explanation?

Accepted Answer

Muscle atrophy due to decreased stimulation and use

Question 16

Which of the following best describes the role of the liver in the Cori cycle during muscle recovery?

Accepted Answer

It converts lactate to pyruvate, then to glucose, which is sent back to muscles.

Question 17

Which of the following is a direct effect of botulism toxin on skeletal muscle?

Accepted Answer

Blocks acetylcholine release at neuromuscular junctions, causing paralysis.

Question 18

Which of the following best explains why fast fibers appear white in histological sections?

Accepted Answer

They contain little myoglobin and have fewer capillaries.

Question 19

Which of the following is a distinguishing feature of intermediate muscle fibers compared to fast and slow fibers?

Accepted Answer

They have more capillaries and are more fatigue-resistant than fast fibers.

Muscle Metabolism, Fatigue, and Fiber Types: Study Notes for ANP College Students

Study Guide - Practice Questions

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