Lactic acid is produced during anaerobic respiration, which is a form of cellular respiration in which oxygen is not present. Lactic acid is produced when you exercise, and it causes your muscles to become tired. It depends how long until you feel the effects of lactic acid, but getting oxygen to your muscles can slow the build-up. Hope this helps! :)
The northerners accepted it because California wanted to be a free state in the union and the southerners rejected it because then it wouldn't be an even number on both sides.