Steps of Muscle Contraction

9. Sarcomere contraction =

Muscle is contracting.

8. After the formation of cross-bridges...

Myosin filaments pull actin filaments toward the center of the sarcomere.

1. The first step...

Nerve impulse is received by the dendrites of the neuron, processed in the cell body, and sent down the axon of the motor neuron.

Basic nerve anatomy

Nerve impulses travel from the dendrites to the axon terminal.

7. After the release of calcium...

Release of calcium from the sarcoplasmic reticulum initiates myosin cross-bridges to actin.

Synapse

The gap between the neuron and muscle fiber at the neuromuscular junction.

11. After the stop of calcium release...

The muscle relaxes.

2. After the nerve impulse travels down the axon...

The nerve impulse arrives at the axon terminals.

Neuromuscular junction

The point at which the motor neuron meets the muscle fiber.

Sliding filament theory

The theory of how muscles contract as myosin filaments pull actin filaments toward the center of the sarcomere.

6. After the start of the muscle fiber's action potential...

When depolarization wave reaches the sarcoplasmic reticulum, calcium is released.

10. After muscle contraction...

Lack of ACh repolarizes the membrane and stops calcium release from the sarcoplasmic reticulum.

5. After the arrival of ACh at the muscle fiber...

Action potential moves across the membrane, which depolarizes it.

4. After ACh enters the synapse...

Acetylcholine binds with ACh receptors on the muscle cell membrane.

Motor unit

A motor neuron and the skeletal muscle fibers innervated by that motor neuron's axon terminals.

3. After the nerve impulse arrives at the axon terminals...

Acetylcholine is stimulated to be released into the synapse.