Section 2d Cholinergic Agonists Flashcards
Where is M2 found? How does it work?
Heart smooth muscle, hyperpolarization (decrease AC & increase K+ opening)
Where is M3 found? How does it work?
Smooth muscle (like GI), Bladder, Exocrine gland; contraction (increase PLC and Ca)
Where is Nm found? How does it work?
skeletal muscle–> End-plate depolarization AND NMJ –> skeletal muscle contraction (open Na/K channels)
Where is Nn found? How does it work?
anatomic ganglia –> depolarization and firing of postganglionic neurons AND adrenal medulla –> secretion of catecholamines (opening of Na/K channels)
What is the effect of a muscarinic agonist on M2? (Heart)
cardiac slowing and decrease in cardiac output, and vasodilation (NO mediated effect)
What is the effect of muscarinic agonist on M3? (GI)
smooth muscle (other than vascular smooth muscle) contracts and peristaltic activity increased (digestion)
What is the effect of muscarinic agonist on M3? (Eye)
contraction of ciliary muscle (effects focus), pupil contraction (miosis), and lowers intraocular pressure in acute glaucoma
What does the NMJ consist of?
motor neuron, motor endplate, synaptic cleft/junctional gap
What is found on the postsynaptic membrane in the synaptic cleft of the NMJ?
ACh receptors adn Acetylcholineesterases
What help ACh release in he NMJ?
Ca2+ and ACh binding to presynaptic neuron (+ feedback loop)
The extent of depolarization in nicotinic receptor end-plate depolarization is dependent upon what?
quantity of ACh
What is it called when a small amount of ACh causes a slight depolarization in the end-plate?
miniature end-plate potential (MEPP)
What is required for muscle contraction?
accumulation of a sufficient concentration of ACh at the motor end plate to depolarize beyond -55mV
What is the major function of indirect acting cholinergic agonists?
Act on acetylcholinesterase
What are direct-acting cholinergic agonists also known as
parasympathomimetics (choline esters & naturally occurring alkaloids)
Which is more specific for Cholinergic receptors, parasympathomimetics or ACh (itself)?
the drugs
What are the 4 major Direct acting cholinergic agonists?
Choline esters: Methacholine, carbachol, bethanechol
Alkaloids: Pilocarpine