Chapter 12: Problem 2

Give an example to show that skeletal muscles work in antagonistic pairs. Explain. (page 255)

Short Answer

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The biceps and triceps muscles in the arm are an example of skeletal muscles working in antagonistic pairs. During arm flexion, the biceps contract and the triceps relax, pulling the forearm up and bringing the hand closer to the shoulder. Conversely, during arm extension, the triceps contract and the biceps relax, moving the forearm away from the shoulder. The roles of these muscles reverse depending on the movement, with one acting as the agonist (prime mover) and the other as the antagonist (opposing muscle). This coordinated function enables smooth and controlled arm movements.

Step by step solution

1. Defining Skeletal Muscles and Antagonistic Pairs

Skeletal muscles are muscles that attach to the bones, and they are responsible for moving the body and maintaining posture. Antagonistic pairs are two muscles that work together to create movement by pulling on the bones in opposite directions. One muscle contracts (shortens) while the other relaxes (lengthens), and they switch roles during the movement to coordinate the action.

2. Providing an Example of Antagonistic Pairs

A good example of skeletal muscles working in antagonistic pairs is the action of the biceps and triceps muscles in the arm. The biceps muscle is located on the front of the upper arm, while the triceps muscle is located on the back.

3. The Biceps and Triceps During Arm Flexion and Extension

When you bend your arm at the elbow (flexion), the biceps muscle contracts, and the triceps muscle relaxes. This shortens the biceps muscle and pulls the forearm up, bringing the hand closer to the shoulder. On the other hand, when you straighten your arm (extension), the triceps muscle contracts, and the biceps muscle relaxes, so the forearm moves away from the shoulder.

4. Role Reversal of Biceps and Triceps

The roles of the biceps and triceps muscles reverse depending on the movement. In the flexion movement, the biceps muscle becomes the agonist (prime mover), while the triceps muscle acts as the antagonist (muscle opposing the prime mover). Conversely, during the extension movement, the triceps muscle becomes the agonist, while the biceps muscle acts as the antagonist.

5. Conclusion

This example shows that skeletal muscles, specifically the biceps and triceps muscles in our arms, work in antagonistic pairs to create movement. The coordinated contraction and relaxation of these two muscles allow for smooth and controlled arm movements.

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Give an example to show that skeletal muscles work in antagonistic pairs. Explain. (page 255)

Short Answer

Step by step solution

1. Defining Skeletal Muscles and Antagonistic Pairs

2. Providing an Example of Antagonistic Pairs

3. The Biceps and Triceps During Arm Flexion and Extension

4. Role Reversal of Biceps and Triceps

5. Conclusion

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