Such a contraction is called a twitch. Thus, each motor unit is either relaxed or each presynaptic action potential causes an action potential in all of the muscle fibers of the motor unit, causing them all to contract at once.In the whole muscle, contractions of different strengths necessarily are created by activating different numbers of motor units.hus, each motor unit is either relaxed or each presynaptic action potential causes an action potential in all of the muscle fibers of the motor unit, causing them all to contract at once. In the whole muscle, contractions of different strengths necessarily are created by activating different numbers of motor units.
Johannes Gutenberg of Mainz, Germany is acknowledged as the first to invent a metal movable-type printing system in Europe, the printing press.
Johannes Gensfleisch zur Laden zum Gutenberg was a German blacksmith, goldsmith, printer, and publisher who introduced printing to Europe with the printing press. His introduction of mechanical movable type printing to Europe started the Printing Revolution and is regarded as a milestone of the second millennium, ushering in the modern period of human history. It played a key role in the development of the Renaissance, Reformation, the Age of Enlightenment, and the scientific revolution and laid