Muscle Contraction Steps

The brain sends a signal, which travels to the spinal cords and finally to the nerves associated with the muscle that is going to contract. The type of neuron that carries the signal to the individual muscle fibers is called a _______________

Motor neuron

The combination of a motor neuron and the muscle fibers that it connects to is called a ______________, which allows each fiber the ability to contract _________________.

Motor unit, simultaneously

When the signal reaches the ______________, this signals the ______________ to release the neurotransmitter ______________.

Synapse, synaptic vesicles, acetylcholine

The _____________ will travel across the ____________ and will attach to the acetylcholine ______________ on the ________________ of the muscle cell.

Acetylcholine, synaptic cleft, receptor site, motor end plate

A wave of excitation and action potential will then travel through the _____________ of the muscle cell and into the ___________ to take the signal deep into the muscle cell.

Sarcolemma, t tubules

This will signal the ____________ to release positive ___________ ions into the myofibrils.

SR, calcium

The ____________ ions will bond with the ________________ complex which will shift the structure to expose the __________ binding sites.

Calcium, troponin-tropomyosion, myosin

The cross bridges will then complete the ______________ to bend and pull the ___________ toward the center of the ______________

Power stroke, actin, sarcomere

As the muscle is contracted, the ______________ will detach and attach farther down the ________ in order to shorten the ____________ more.

Myosin heads, actin, sarcomere

As the ____________ shortens, the actin is pulled toward the _________ at the center, and the __________ and __________ will become shorter, and may disappear if the muscle is fully contracted. The _____________ will remain the same size and the ___________ will come closer together.

Sarcomere, M Line, I Band, H Zone, A band, Z discs

As the muscle relaxes, the enzyme ______________ will break down the neurotransmitter ________________. This will cause the ____________ ions to diffuse back into the _______________ and the ________________ complex to shift back into place and cover the _____________ binding sites

Acetylcholinesterase, acetylcholine, calcium, sarcoplasm, troponin-tropomyosin, myosin