The ( ortho- ) sympathetic nervous system ( SNS ) is one of three major parts of the autonomic nervous system : the others being the enteric and parasympathetic systems.
The adrenergic receptors (or adrenoceptors ) are a class of G protein-coupled receptors that are targets of the catecholamines , especially norepinephrine (noradrenaline) and epinephrine (adrenaline). Many cells possess these receptors, and the binding of a catecholamine to the receptor will generally stimulate the sympathetic nervous system .
Norepinephrine ( INN ) (abbreviated norepi or NE ), or noradrenaline ( BAN ) (abbreviated NA , NAd , or norad ), is a catecholamine with multiple roles including as a hormone and a neurotransmitter . [ 3 ] Areas of the body that produce or are affected by norepinephrine are described as noradrenergic .
Epinephrine (also known as adrenaline or adrenalin ) is a hormone and a neurotransmitter . [ 1 ] Epinephrine has many functions in the body, regulating heart rate , blood vessel and air passage diameters, and metabolic shifts; epinephrine release is a crucial component of the fight-or-flight response of the sympathetic nervous system . [ 2 ] In chemical terms, epinephrine is one of a group of monoamines called the catecholamines .
Red Blood Cells and Chronic Fatigue Syndrome
A pheochromocytoma (Etymology: Greek "phaios =dark, chroma = color, kytos =cell, oma = tumor") or phaeochromocytoma ( PCC ) is a neuroendocrine tumor of the medulla of the adrenal glands (originating in the chromaffin cells ), or extra-adrenal chromaffin tissue that failed to involute after birth [ 1 ] and secretes high amounts of catecholamines , usually noradrenaline ( norepinephrine ), and adrenaline ( epinephrine ) to a lesser extent. [ 2 ] Extra-adrenal paragangliomas (often described as extra-adrenal pheochromocytomas) are closely related, though less common, tumors that originate in the ganglia of the sympathetic nervous system and are named based upon the primary anatomical site of origin.
Ghrelin is a 28 amino acid hunger-stimulating peptide and hormone that is produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas . [ 1 ] Ghrelin together with obestatin is produced from cleavage of the ghrelin/obestatin prepropeptide (also known as the appetite-regulating hormone or growth hormone secretagogue or motilin-related peptide ) which in turn is encoded by the GHRL gene .