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.
Norepinephrine is a neurotransmitter secreted by neurons in the sympathetic nervous system. This chemical is secreted in response to stress, which triggers the 'fight or flight response.' The release of norepinephrine causes several changes that help our body to work more efficiently.
Epinephrine is normally produced by both the adrenal glands and certain neurons. It plays an important role in the fight-or-flight response by increasing blood flow to muscles, output of the heart, pupil dilation, and blood sugar.Epinephrine does this by its effects on alpha and beta receptors.pinephrine, also known as adrenaline, is a medication, hormone and neurotransmitter. As a medication it is used for a number of conditions including: anaphylaxis, cardiac arrest, and superficial bleeding.