Homestasis is the maintenance of a steady state within the body so that it can function at optimal levels. The nervous system is responsible for responding to stimuli which are ever-changing. For instance, if a person is injured, the nervous system will respond with a reflex action. It will also register pain which is a signal that something is wrong. Neurons are constantly sending impulses to the brain and spinal cord, which in turn send impulses back to muscles and glands allowing the body to respond to various stimuli. The nervous system is acts very quickly to maintain homeostasis. The endocrine system on the other hand, releases hormones from ductless endocrine glands. They are sent via the circulating blood to specific receptors and then something will happen in the body as a result. Hormones act slowly over long periods of time, in contrast to the nervous system. An example is growth hormone. As the pituitary gland releases growth hormone(HGH)into the blood, this will cause the multiplication of bone cells and result in growth. Both the nervous system and endocrine system are vital to maintain homeostasis in the body.