Question

Put these myofibers in the order they would be recruited as the body moves from a weak to a strong stimulus:

1. glycolytic fast-twitch fibers
2. fatigue-resistant oxidative fast-twitch fibers
3. fatigue-resistant slow-twitch fibers
A) 1, 2, 3
B) 2, 3, 1
C) 3, 2, 1
D) 1, 3, 2
E) 3, 1, 2

Answer 1

The recruitment order from a weak to a strong stimulus begins with fatigue-resistant slow-twitch fibers, then oxidative fast-twitch fibers, and finally glycolytic fast-twitch fibers. The correct sequence is slow, oxidative, then glycolytic, corresponding to answer C) 3, 2, 1.

Step-by-step explanation:

The recruitment order of myofibers as the body moves from a weak to a strong stimulus starts with those most resistant to fatigue and requiring the least energy to function, and ends with those that provide the most rapid and powerful contractions but fatigue quickly.

1. Fatigue-resistant slow-twitch fibers
2. Fatigue-resistant oxidative fast-twitch fibers
3. Glycolytic fast-twitch fibers

Fatigue-resistant slow-twitch fibers use aerobic metabolism and are efficient at using oxygen, enabling them to work for long periods and resist fatigue. Fatigue-resistant oxidative fast-twitch fibers are also efficient but can switch to anaerobic metabolism under certain conditions, leading to quicker fatigue than slow-twitch fibers. Finally, the glycolytic fast-twitch fibers rely on anaerobic metabolism, making them powerful but they fatigue rapidly.

Hence, the correct order from a weak to a strong stimulus is slow-twitch fibers, oxidative fast-twitch fibers, and finally glycolytic fast-twitch fibers, making the answer C) 3, 2, 1.