So if you ever hear the expression motor and plate, that simply is referring to the synapse between our end of the motor neuron and our sarcoplasm of our muscle cell. This is also known as the neuromuscular junction. So now that we know how the signal actually arrives onto our muscle cell and what it causes, let's see what the calcium actually does and how it interacts with the thin and thick filament. So this is our sarcomere. The sarcomir consists of these thin filaments that are composed of globular proteins known as actin. And we also have the thick filaments, shown in purple, that are composed of our protein known as myosin.