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 an important cell signaling molecule in the fight or flight response. Also known as adrenaline, epinephrine is an efficient messenger that signals many cell types throughout the body with many effects. In the lungs, epinephrine binds to receptors on smooth muscle cells wrapped around the bronchioles.pinephrine is an important cell signaling molecule in the fight or flight response. Also known as adrenaline, epinephrine is an efficient messenger that signals many cell types throughout the body with many effects. In the lungs, epinephrine binds to receptors on smooth muscle cells wrapped around the bronchioles.