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 Gutenberg got rid of the woodblock ideas and tried to work with metal. He decided it worked very well and was completing the first book ever printed by his new invention, which was movable type. The first book was the Bible, which was printed in Latin. His invention was called the printing press. Soon enough the blacksmith that Johannes Gutenberg was working for lost faith in him and decided to take him to court. The judge favored with Fust, so everything Gutenberg worked on and owned belonged to Fust. Johannes Gutenberg ended up dying in Mainz, Germany in 1468.