How is the endocrine system related to the nervous system?
Both systems are very closely related because they exert control over all other body systems through homeostasis.
Endocrine System is for releasing hormones into the bloodstream.
This production, secretion, and transport takes a long time.
The Nervous System responds much more quickly, since it uses electrochemical impulses---signals---to communicate from neuron (nerve cell) to neuron or to its target tissue.
For example, the autonomic nervous system can release epinephrine (adrenaline).
Here, Epinephrine from neurons acts as a 'neurotransmitter'.
It does this at the ends of sympathetic neurons causing a 'fight or flight' response almost immediately.
However, it merges directly with hormones when this same system--sympathetic neurons--coincide at the adrenal medulla.
This adrenal medulla contains both Epinephrine and Norepinephrine, as well as tons of blood vessels. These vessels will allow for immediate
transport of those chemicals, now called 'hormones',
to various body parts.
Here is another example.
When you lose some blood from bleeding, the body responds immediately (by constricting the blood vessels).
This is the Nervous System using a 'sympathetic' response.
In addition, hormones will also be 'called upon' and released, such as renin, angiotensin, and aldosterone.
These hormones also help with blood vessel constriction.
In addition, they do much more, like water retention.
This will help 'preserve' the blood still there and also raise blood volume.