Q: What exactly are urban legends? A: Urban legends are popular stories alleged to be true and passed from individual to individual via oral or written (e.g. forwarded email) communication.: What exactly are urban legends? A: Urban legends are popular stories alleged to be true and passed from individual to individual via oral or written (e.g. forwarded email) communication.
When a person gets injured, their brains release chemicals called opioids into the space between neurons that acts to dull the pain signals. The effect is seen the most in the brain regions called the ventral striatum, amygdala, midline thalamus, and periaqueductal gray.
Lesson Summary. 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.t is classified as a neurotransmitter, a chemical that is released from neurons. Because the release of norepinephrine affects other organs of the body, it is also referred to as a stress hormone.