Activity 2: How do muscles work? Materials needed: muscles in the body
Procedures:
1. Stretch your arm and feel the muscles in your upper arm. Observe what will happen to your upper arm when relaxed. Record your observation in the Observation Table.
2. Bend your arm. Feel again the muscles in the upper arm. Observe what happens to the muscles when they contract. Repeat step 1 and 2. This time try your muscles in the lower leg.
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Answer:
Muscle in the upper arm
•Muscles when relax
When your biceps muscle in your upper arm contracts, it pulls your lower arm in towards your shoulder. However, when it relaxes, your biceps cannot push your arm back out. To do this, your triceps muscle, on the underside of your upper arm, contracts and straightens your arm out.
•Muscle when contacted
There are three muscles on the upper arm that are parallel to the long axis of the humerus, the biceps brachii, the brachialis, and the triceps brachii. The biceps brachii is on the anterior side of the humerus and is the prime mover (agonist) responsible for flexing the forearm.
Muscle in the lower arm
•muscles when relax
to raise the forearm, the biceps contracts and the triceps relaxes.
•Muscle when contacted
to lower the forearm again, the triceps contracts and the biceps relaxes.
Explanation:
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