"The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the nervous system that supplies internal organs, smooth muscle and glands."
The part of the nervous system that regulates the body's involuntary functions such as heart rate, breathing, and digestion.
Anatomy and Physiology of Autonomic Nervous System: This topic discusses the structure, function, and components of the autonomic nervous system (ANS), including sympathetic and parasympathetic divisions, their pathways, and their roles in regulating various organ systems.
Neurotransmitters and Receptors: This topic covers the various neurotransmitters and receptors involved in the function of the ANS, including acetylcholine, norepinephrine, and their respective receptors.
Autonomic Reflexes: This topic describes the different types of autonomic reflexes, including baroreflex, chemoreflex, and Bezold-Jarisch reflex, and how they help regulate homeostasis in the body.
Autonomic Dysfunction: This topic covers the various forms of autonomic dysfunction, including autonomic neuropathies, postural orthostatic tachycardia syndrome (POTS), and other dysautonomias, and the associated symptoms and treatments.
Autonomic Testing: This topic discusses the different types of autonomic testing, including heart rate variability, tilt table testing, and quantitative sudomotor axon reflex test (QSART), and their use in diagnosing autonomic dysfunction.
Autonomic Pharmacology: This topic covers the various classes of drugs used to treat autonomic dysfunction, including sympathomimetics, alpha and beta blockers, and cholinesterase inhibitors.
Autonomic Control of the Heart: This topic describes how the ANS regulates heart rate, blood pressure, cardiac output, and other cardiovascular functions.
Autonomic Control of Respiration: This topic covers how the ANS regulates respiratory rate, depth, and rhythm, as well as gas exchange and ventilation.
Autonomic Control of Digestion: This topic describes how the ANS regulates digestion, including gastric motility, intestinal motility, and pancreatic secretions.
Autonomic Control of Urinary System: This topic covers how the ANS regulates bladder function, urethral sphincter control, and urinary retention.
Autonomic Control of Thermoregulation: This topic describes how the ANS regulates body temperature, including sweating, shivering, and vasodilation/constriction.
Autonomic Control of Eye: This topic covers how the ANS regulates pupil size, intraocular pressure, and tear production.
Autonomic Control of Glands: This topic describes how the ANS regulates glandular secretion, including salivary, lacrimal, and sweat glands.
Autonomic Control of Reproductive System: This topic covers how the ANS regulates reproductive functions, including erection and ejaculation in males and menstruation and uterine contractions in females.
Autonomic Control of Immune System: This topic describes the role of the ANS in modulating immune function and the potential consequences of autonomic dysfunction on immune-mediated diseases.
Sympathetic Nervous System: This is the portion of the autonomic nervous system that acts on the body in times of stress, danger or excitement, preparing it for a "fight or flight" reaction. It increases heart rate, breathing rate, and blood pressure, dilates the pupils, and shifts blood flow away from the digestive system and towards the muscles and organs needed for action.
Parasympathetic Nervous System: This is the portion of the autonomic nervous system that regulates the body's resting or "rest and digest" state. It slows heart rate and breathing rate, relaxes blood vessels, constricts the pupils, and increases digestive and urinary function.
Enteric Nervous System: This is a network of neurons in the digestive system that controls its function, including the movement of food and the secretion of digestive enzymes.
Sympathetic Chain Ganglia: These are paired clusters of nerve cells located on either side of the spinal cord that relay messages from the sympathetic nervous system to various organs and tissues.
Prevertebral Ganglia: These are clusters of nerve cells located outside the spinal cord that also relay messages from the sympathetic nervous system to organs and tissues, particularly those of the abdomen.
Adrenal Medulla: This is a specialized component of the sympathetic nervous system located in the adrenal glands. It secretes hormones called catecholamines (such as adrenaline and noradrenaline) that help the body respond to stress.
"The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, its force of contraction, digestion, respiratory rate, pupillary response, urination, and sexual arousal."
"This system is the primary mechanism in control of the fight-or-flight response."
"The autonomic nervous system is regulated by integrated reflexes through the brainstem to the spinal cord and organs."
"Autonomic functions include control of respiration, cardiac regulation (the cardiac control center), vasomotor activity (the vasomotor center), and certain reflex actions such as coughing, sneezing, swallowing, and vomiting."
"The hypothalamus, just above the brain stem, acts as an integrator for autonomic functions, receiving autonomic regulatory input from the limbic system."
"The autonomic nervous system has historically been considered a purely motor system, and has been divided into three branches: the sympathetic nervous system, the parasympathetic nervous system, and the enteric nervous system."
"The sympathetic nervous system is often considered the 'fight or flight' system, while the parasympathetic nervous system is often considered the 'rest and digest' or 'feed and breed' system."
"In many cases, both of these systems have 'opposite' actions where one system activates a physiological response and the other inhibits it."
"A third subsystem of neurons has been named as non-noradrenergic, non-cholinergic transmitters (because they use nitric oxide as a neurotransmitter) and are integral in autonomic function, in particular in the gut and the lungs."
"Although the ANS is also known as the visceral nervous system and although most of its fibers carry non-somatic information to the CNS, many authors still consider it only connected with the motor side."
"Most autonomous functions are involuntary but they can often work in conjunction with the somatic nervous system which provides voluntary control."