Parasympathetic NS Flashcards
what is antagonistic control?
the sympathetic and parasympathetic systems having opposing effects
what is the order of a nervous impulse in the parasympathetic NS?
CNS to the NIC receptor in the ganglia, to the M receptor to the effector
what kind of receptor is a Muscarinic receptor?
a G-protein coupled receptor
what are M1 receptors?
neural receptors that are located in the brain and the stomach
what are M2 receptors?
cardiac receptors that are located in the heart
what are M3 receptors?
smooth muscle receptors that are located in the ey, GI tract, bladder and the lungs
what are the choline esters receptor agonists?
acetylcholine, methacholine, carbachol and bethanechol
why is acetylcholine not used?
has an effect on nicotinic and Muscarinic receptors so all subtypes are stimulated and is short lived due to being effected by AChE
what are the features of methacholine?
not effected by AChE so longer lasting effects and has the most Muscarinic action
what are the features of carbachol?
causes nicotinic action when other don’t
what is bethanechol used to treat?
glaucoma
what effects does bethanechol have?
increases GI peristalsis and bladder contraction
what are the adverse effects of bethanechol?
colic, diarrhoea, low BP, bronchoconstriction and sweating
what are the alkaloid Muscarinic agonists?
muscarine, pilocarpine and arecoline
what is pilocarpine used for? how does it work?
treatment of glaucoma, it is lipid soluble so is able to penetrate the cornea and constrict the pupillae muscle
what is the effect of arecoline?
has Muscarinic and nicotonic effects on the CNS
what are the Muscarinic effects caused by agonists?
pupil constriction, lower heart rate, increased GI motility, salivation, bronchoconstriction and bladder contraction
what are the key features of the Muscarinic agonists that are used clinically?
stimulate muscarinic receptors with little effect on nicotinic receptors, are not broken down by AChE, have prolonged action
what can muscarinic antagonists be used to treat?
bradycardia, during anaesthesia to block vagal slowing of the heart and to promote bronchodilation in
what are the side effects of muscarinic antagonists?
dry mouth, constipation and urinary retention, tachycardia
what are subtype selective muscarinic antagonists?
drugs that have been developed so that they are more selective for one particular subtype
what are examples of subtype selective antagonists?
pirenzepine and darifenacin
what does pirenzepine do?
blocks M1 receptors that are involved in gastric acid secretion
what can pirenzepine be used for?
anti-ulcer treatment
what does darifanacin do?
selectively blocks M3 receptors
what is darifanacin used for?
to treat urinary incontinence due to inhibiting parasympathetic contraction of the bladder
