Question

1. write down the following in a correct order from the lowest to the highest levels of organization. Myosin, Myofibril, Troponin, Calcium ions, muscle fibers, sacroplasm, Acetylcholine

2. What is a motor unit?

3. What is the latent period?

Answer 1

1. From lowest to the highest levels of organization:

- caclium ions

- Acetylcholine

- Troponin

- Myosin

- Sarcoplasm

- Myofibril

- Muscle fiber

2. A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals.

3.  The latent period :
- It is a short delay (1-2 msec) from the time when the action potential reaches the muscle until tension can be observed in the muscle.
- This is the time required for the calcium to diffuse out of the SR, bind to troponin, the movement of tropomyosin off of the active sites, formation of cross bridges, and taking up any slack that may be in the muscle.