Describe the roles of the nervous system in homeostasis.

Homeostasis is a maintenance of a constant internal environment.
The human nervous system consists of central nervous system; brain and spinal cord and peripheral nervous system which is subdivided into autonomic (involuntary eg. sweating when too warm) and somatic (voluntary eg. going to toilet to empty your bladder).
Autonomic nervous system is mainly concerned with homeostasis of the body. Autonomic nervous system can be further divided into two:
-parasympathetic; most active in resting state
-sympathetic; activated in flight or fight mode


Receptors inside and outside the body are constantly monitoring conditions and watching for changes eg.thermoreceptors in the skin and hypothalamus 
When a body system leaves a set point eg. temperature in our body increases beyond 37 degrees C and falls outside its normal range, receptors inside and outside the body monitor the changes, send messages through the nervous system to an appropriate regulator which trigger responses to bring the system back into the normal range of functioning. Eg. hypothalamus would send messages to tell you you’re too warm and maybe remove a piece of clothing, while skin receptors would dilate blood vessels, so more heat is lost through the skin.
A negative feedback loop restores the balance to an optimum.