Question

2 multiple choice 1 point
skeletal muscle groups that work together to create the same movement of a body part are referred to as
involuntary.
myofibrils.
synergistic.
antagonistic.
sarcomeres.
3 multiple choice 1 point
the following events are associated with muscle contraction. which one of the following lists the correct order following the initiation of a contraction by a nerve impulse?

1. t-tubules transmit electrical impulses throughout the muscle cell.
2. myosin contacts actin and pulls it toward the center of the sarcomere.
3. acetylcholine binds to receptors on the muscle.
4. troponin-tropomyosin complex shifts to expose myosin binding sites.
5. calcium is released from the sarcoplasmic reticulum.

Explanation:

For question 2:

• Involuntary refers to muscle control, not paired movement.
• Myofibrils are structural muscle components, not groups.
• Synergistic muscles work together for the same movement.
• Antagonistic muscles oppose each other's movement.
• Sarcomeres are the contractile units of myofibrils.

For question 3 (correct order):

1. First, the nerve impulse triggers acetylcholine binding to muscle receptors.
2. Next, T-tubules carry the electrical signal through the muscle cell.
3. This signal causes calcium release from the sarcoplasmic reticulum.
4. Calcium allows the troponin-tropomyosin complex to shift, exposing binding sites.
5. Finally, myosin contacts and pulls actin to contract the sarcomere.

Answer:

1. C. synergistic.
2. 3, 1, 5, 4, 2
3. Acetylcholine binds to receptors on the muscle.
4. T-tubules transmit electrical impulses throughout the muscle cell.
5. Calcium is released from the sarcoplasmic reticulum.
6. Troponin-tropomyosin complex shifts to expose myosin binding sites.
7. Myosin contacts actin and pulls it toward the center of the sarcomere.