Overview of autonomic nervous system

===Lecture Details===
Helena Parkington; Week 4 MED1022; Physiology
===Lecture Content===
ANS is involved in homeostasis. Is divided into sympathetic and parasympathetic (fight/flight, rest/digest). Parasympathetic accepts inputs from sensory nerves, has an interneuron and then a preganglionic axon to the viscera. Synapses in nucleus tractus solitarius in the parasympathetic system in the brainstem.
Preganglionic cell bodies are in the eye (Edinger-Westphal nucleus), tears, salivary glands, parotid gland, chest and abdominal viscera have nuclei in brainstem. Axonal output is CN3, 7, 9, 10 and 11 (vagal output), also to sacral S2-4 (pelvic organs).
Preganglionic cells are myelinated, postganglionic are not. There is a lot of ACh integration in ganglia from small, subthreshold EPSPs; varicosities exist in effector tissue in efferents. Varicosities locally produce small molecule transmitters. In postganglionic neurons, gaps are called junctions rather than synapses.
Sympathetic system uses NA, ATP and peptides such as neuropeptide Y. Parasympathetic uses ACh, NO and peptides.
Developing nerves from the fetus become either ganglion cells or adrenal medullary cells.
Arcuate nucleus is involved in feeding; paraventricular nucleus with glucose control, dorsomedial with fat metabolism, preoptic with sexual responses, supraoptic with sexual response.
Brainstem has CV and resp centres, micturition centre, vagal outflow and medulla. Nucleus tractus solitarius recieves information; paraventricular nucleus is part of the hypothalamus; locus cereleus distributes information; rostral ventrolateral medulla collects information; caudal ventrolateral medulla is major output control.
Cortex is thought, sight, limbic is satiety, aggression, flight, thalamus recieves and distributes information. Anorexigenic molecules are POMC, aMSH, cocaine and amphetamine, corticotropin regulated hormone. Orexigenic are neuropeptide Y, melanin concentration hormone and agouti-related peptide. Leptin stimulates fat storage by acting on the arcuate nucleus neurons.
Referred pain refers to common second order neurons. White ramus communicans communicates between spinal nerves and the sympathetic chain.
Penile artery is vasodilated by NO and constricted by NA. Vas deferens has NA for slow contraction and ATP for fast contraction. Vaginal secretion is modulated by CGRP which is a vasodilator. Parasympathetic is NO, sympathetic is ejaculations and constrictions.
NO increases Ca which activates NOS. Synthesises NO from arginine, which acts to create cGMP and activate PKG (pathway which viagra acts on).
All main neurotransmitters are ACh except for the junctional end of the sympathetic system which secretes NA. Synaptic receptors are fast, have a change in membrane potential. Extrasynaptic receptors are slower; change in membrane potential isn't necessary eg muscarinic. All receptors are metabotropic barring one.
===Readings===
Bear, Neuroscience 15