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Autonomic nervous system, showing splanchnic nerves in middle, and the vagus nerve as "X" in blue. The heart and organs below in list to right are regarded as viscera. The autonomic nervous system has been classically divided into the sympathetic nervous system and parasympathetic nervous system only (i.e., exclusively motor).
The autonomic nervous system is a control system that acts largely unconsciously and regulates heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. This system is the primary mechanism in control of the fight-or-flight response and its role is mediated by two different components: the sympathetic nervous ...
The visceral part, also known as the autonomic nervous system, contains neurons that innervate the internal organs, blood vessels, and glands. The autonomic nervous system itself consists of two parts: the sympathetic nervous system and the parasympathetic nervous system. Some authors also include sensory neurons whose cell bodies lie in the ...
In humans and most mammals, the autonomic nervous system and hypothalamic-pituitary-adrenal (HPA) axis are the two major systems that respond to stress. [3] Two well-known hormones that humans produce during stressful situations are adrenaline and cortisol .
The term autonomic is an anatomical term and it refers to a type of nervous system in animals and humans that is very primitive. Skeletal or somatic are, similarly, anatomical terms that refer to a type of nervous system that is more recent in terms of evolutionary development. There are autonomic reflexes and skeletal, somatic reflexes. [8]
The tenth (X) cranial nerve, (the vagus nerve) – part of the autonomic nervous system – then produces bradycardia and other neural pathways elicit peripheral vasoconstriction, restricting blood from limbs and all organs to preserve blood and oxygen for the heart and the brain (and lungs), concentrating flow in a heart–brain circuit and ...
The binding to these receptors by catecholamines will generally stimulate the sympathetic nervous system, the arm of the autonomic nervous system responsible for the fight-or-flight response. Adrenergic receptor autoantibodies are autoantibodies (antibodies directed against a person's own protein) targeting adrenergic receptors.
The underlying mechanism involves the nervous system slowing the heart rate and dilating blood vessels, resulting in low blood pressure and thus not enough blood flow to the brain. [2] Diagnosis is based on the symptoms after ruling out other possible causes. [3] Recovery from a reflex syncope episode happens without specific treatment. [2]