In 1913 Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus.n 1913 Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus.
Norepinephrine, also called noradrenaline, is an organic chemical in the catecholamine family that functions in the human brain and body as a hormone and neurotransmitter.n the most basic terms, the function of norepinephrine is to mobilize the brain and body for action. Norepinephrine release is lowest during sleep, rises during wakefulness, and reaches much higher levels during situations of stress or danger, in what has been called the fight-or-flight response.
Norepinephrine is synthesized and released by the central nervous system and also by a division of the autonomic nervous system called the sympathetic nervous system.orepinephrine is a catecholamine and a phenethylamine. Its structure differs from that of epinephrine only in that epinephrine has a methyl group attached to its nitrogen, whereas the methyl group is replaced by a hydrogen atom in norepinephrine.