Autonomic Nervous Syetm: Cholinergic system Flashcards
(77 cards)
what is the parasympathetic system
regulates body functions during rest, digest and waste elimination
- increases the activity of gastrointestinal and genitourinary systems and decreases the activity of cardiovascular systems
what is the neurotransmitter for the cholinergic system
acetylcholine
which ones are cholinergic
preganglionic neurons and postganglionic para-sympathetic neurons
what ais the emaning of cholinergic and anticholinergic drugs
cholinergic drugs are used to increase parasympathetic activity, and used for such as urinary and intestinal stasis, glaucoma, alzheimer’s disease and myasthenia gravis
anticholinergics are drugs that decrease the parasympathetic activity and used for treatment of overactive urinary and interstinal conditions, asthma, and during various ophthalmic procedures
what is thr process for synthesis and storage of acetylcholine
ach is synthesised from choline and actyle-CoA via choline acetyltransferase
- choline accumulated in cholinergic presynaptic nerve ending via active transport mechanism linked to Na+ pump
what drug inhibits the cholineb iptake into nerve ending and what is the effect
hemicholinium
- decreased Ach sythesis
what happens after synthesis of ach
ach synthesized is actively transported into vesicles and stored by the vesicular acetylcholine transporter
what drug inhibits vesicular acetylcholine transporter
vacht can be inhibited by vesamicol and result in. reduced acetylcholine loaded into synaptic vesicles and released
result in less parasympathetic activity
process of release of acetylcholine
presynaaptic membrane depolarization opens voltage dependent ca2+ channels , and influx of the ion causes fusion of the synaptic vesicle membranes with the presynaptic membrane, leading to exocytosis of Ach
what drug prevents the release of Ach and how is it used
botulinum toxin prevents Ach release and used for dystonia and cosmetics
what is dystonia
movement disorder in thich a person’s muschels contract uncontrollably , contraction causes the affected body part to twist involuntarily, resulting in repetitive movements or abnormal postures
how is action of Ach terminated
acetylcholineeasterase(AchE)
there is also butyrylcholinesterase , that differ in their distribution, substrate specificity and function
they both convert Ach into choline and acetate
synapse and function to destroy Ach to prevent over stimulation
at skin, liver, brain muscle, and blood
when inhibited ,level of Ach increases
reversible AchE inhibitors
edrophonium
physostigmine
neostigmine
irrevisible AchE inhibitors
malathion and parathion( they are organophosphates)
since it is irrevisble, tjey increase the Ach levels exponentiallly
what is the function of pralidocime
reactives cholinestersae which are inactived by phosphorylation due to an organophosphate pesticide or related compound(malathion and parathion)
-thye have high level of affinity for phosphate groups
what is the warning for pralidoxime
it can only be used when we know that the AchE is inhibited by oligophosphates
if given without it, since they have weak inhibitory activity on AchE, further inhibit AchE and causes it to be worse
also they have to be administered very early when we know the action, bc when oligophosphates are administered, they undergo further medications that will result in a irreveisble process and then the phosphate group cannot be replaced
what are the post junctional receptors for Ach
muscarinic and nictonic
- target sites for activating drugs(direct acting cholinometics) and blocking drugs
the affinity of muscarinic receptors
muscarine
acetylcholine
nicotine
affinity of nicotinic receptors
nicorine
acetylcholine
muscarine
direct acting cholinomimetics
acts direcly on receptor
indirect acting cholinomimetics
inhibition of cholinesterase and prolong action of Ach
cholinoceptor antagonist
block muscranic receptor
block nicotinic receptor
cholinesterae regenerators which are not receptor blockers but are chemical antagonist of organophosphate acetylinesterase inhibitors
what are muscranic receptors
g protein couples receptors whcih respon to muscarine as well as Ach
- m1,m2,m3
signalling trasndcution involved for muschrnic receptor
m1 and m3 - phosphatidylinositol pathway
m2- cAMP pathway