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.
Gutenberg Bible of the New York Public Library. Bought by James Lenox in 1847, it was the first copy to be acquired by a United States citizen. The Gutenberg Bible (also known as the 42-line Bible, the Mazarin Bible or the B42) was the first major book printed using mass-produced movable metal type in Europe. It marked the start of the Gutenberg Revolution and the age of the printed book in the West.