The head of a Roman snail, four tentacles well visible. [RN] Observing a snail crawling around, the view is immediately attracted by its head, orienting itself in its surroundings using the tentacles. The snail feels its environment, touches an obstacle and withdraws the tentacle.
One of these hormones is epinephrine, which can be defined as a hormone secreted by the adrenal medulla in response to short-term stress. Epinephrine is also called adrenaline, and you may have heard of this term before.
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.