title: An introduction into autonomic nervous function.
abstract: The results of many medical measurements are directly or indirectly influenced by the autonomic nervous system (ANS). For example pupil size or heart rate may demonstrate striking moment-to-moment variability. This review intends to elucidate the physiology behind this seemingly unpredictable system. The review is split up into: 1. The peripheral ANS, parallel innervation by the sympathetic and parasympathetic branches, their transmitters and co-transmitters. It treats questions like the supposed sympatho/vagal balance, organization in plexuses and the 'little brains' that are active like in the enteric system or around the heart. Part 2 treats ANS-function in some (example-) organs in more detail: the eye, the heart, blood vessels, lungs, respiration and cardiorespiratory coupling. Part 3 poses the question of who is directing what? Is the ANS a strictly top-down directed system or is its organization bottom-up? Finally, it is concluded that the 'noisy numbers' in medical measurements, caused by ANS variability, are part and parcel of how the system works. This topical review is a one-man's undertaking and may possibly give a biased view. The author has explicitly indicated in the text where his views are not (yet) supported by facts, hoping to provoke discussion and instigate new research.
authors.affiliation: Department of Anatomy, Embryology and Physiology, Academic Medical Center at the University of Amsterdam, Amsterdam, Netherlands.
authors.forename: John M
authors.initials: JM
authors.lastname: Karemaker
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D010275:Parasympathetic Nervous System / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology