✔ 最佳答案
autonomic nervous system (ANS) (or visceral nervous system) is the part of the peripheral nervous system that controls homeostasis, that is the constancy of the content of tissues in gasses, ions and nutrients. It does so mostly by controlling cardiovascular, digestive and respiratory functions, but also salivation, perspiration, diameter of the pupils, micturition - (the discharge of urine), and erection. Many of the activities of the ANS are involuntary. However, breathing, for example, can be in part consciously controlled. Indeed, although breathing is a purely homeostatic function in aquatic vertebrates, in land vertebrates it accomplishes much more than oxygenating the blood: it is essential to sniff a prey or a flower, to blow a candle, to talk or sing. This example, among others, illustrates that the so-called “autonomic nervous system” is not truly autonomous. It is anatomically and functionally linked to the rest of the nervous system and a strict delineation is impossible.
http://en.wikipedia.org/wiki/Autonomic_nervous_system
have all your answer
