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SPHINCTER
| Pronunciation (US): |  | (GB): | |
I. (noun)
Sense 1
Meaning:
A ring of muscle that contracts to close an opening
Synonyms:
anatomical sphincter; sphincter; sphincter muscle
Classified under:
Hypernyms ("sphincter" is a kind of...):
muscle; musculus (one of the contractile organs of the body)
Hyponyms (each of the following is a kind of "sphincter"):
physiological sphincter (a sphincter that is not recognizable at autopsy because its resting arrangement cannot be distinguished from adjacent tissue)
anal sphincter; musculus sphincter ani; sphincter ani (the sphincter muscle of the anus)
musculus sphincter urethrae; urethral sphincter (a striated sphincter muscle that constricts the urethra)
bladder sphincter; musculus sphincter vesicae (the sphincter muscle of the urinary bladder; made up of a thickened muscular layer of bladder around the urethral opening)
musculus sphincter ductus choledochi (the smooth muscle sphincter of the common bile duct)
musculus sphincter ductus pancreatici (the smooth muscle sphincter of the main pancreatic duct)
musculus sphincter pupillae; pupillary sphincter (a ring of smooth muscle surrounding the iris)
musculus sphincter pylori; pyloric sphincter; pyloric valve (the sphincter muscle of the pylorus that separates the stomach from the duodenum)
Context examples:
Administered in the eye, cyclopentolate hydrochloride blocks the acetylcholine receptor in the sphincter muscle of the iris and the ciliary muscle, thereby preventing contraction.
(Cyclopentolate Hydrochloride, NCI Thesaurus)
Cinametic acid relaxes the sphincter of Oddi and regulates hepato-biliary function.
(Cinametic Acid, NCI Thesaurus)
When administered in the conjunctiva, this agent binds to alpha-adrenergic receptors in the iris sphincter muscle, resulting in vasoconstriction, a decrease in the production of aqueous humor, and a lowering of intraocular pressure.
(Epinephrine Hydrochloride, NCI Thesaurus)
This causes contraction of the iris sphincter muscle (producing miosis) and the ciliary muscle (affecting the accommodation reflex).
(Demecarium, NCI Thesaurus)
When applied topically to the eye, this agent stimulates the sphincter pupillae to contract, resulting in miosis; stimulates the ciliary muscle to contract, resulting in spasm of accomodation; and may cause a transitory rise in intraocular pressure followed by a more persistent fall due to opening of the trabecular meshwork and an increase in the outflow of aqueous humor.
(Pilocarpine Hydrochloride, NCI Thesaurus)
When applied topically to eyes, this agent stimulates the sphincter pupillae to contract, resulting in miosis; stimulates the ciliary muscle to contract, resulting in spasm of accommodation; and may cause a transitory rise in intraocular pressure followed by a more persistent fall due to opening of the trabecular meshwork and an increase in the outflow of aqueous humor.
(Pilocarpine, NCI Thesaurus)
Researchers grew human prostate cancer cells in laboratory dishes along with human muscle cells—stand-ins for the smooth muscle surrounding the prostate gland and the striated muscle of the urethral sphincter at the base of the prostate.
(Proximity to muscle cells may promote spread of prostate cancer cells, National Institutes of Health)
Metoclopramide binds to dopamine 2 (D2) receptors in the peripheral nervous system (PNS), antagonizing dopamine-mediated relaxation of gastrointestinal smooth muscle and promoting gastroprokinesis; the pyloric sphincter and the duodenal bulb are relaxed, peristalsis of the duodenum and jejunum increase, and gastric emptying and intestinal transit accelerate.
(Metoclopramide Hydrochloride, NCI Thesaurus)
