In: Biology
Describe the two broad classes of cholinergic receptors: nicotinic and muscarinic, provide details relating to the termination of ACh action (150-word limit).
Ans:- nicotinic receptors are inotropic acetylcholine receptor. nicotinic receptor are ligand gated ion channel which contain membrane bound protein which allow passage of ion like sodium, potassium, chloride through membrane in response to chemical messenger (nicotine). nicotine acetylcholine receptor are made up of five subunit. nicotinic acetylcholine receptor are found at postsynaptic side of neuro muscular junction, it is get activated by acetylcholine release ay synapse.acetylcholine produce muscular contraction.
muscarinic receptor are metabotropic which is act by second messenger and particularly responsive to muscarine. muscarinic receptors are not ion gated channel but G- protein coupled receptor which act by second messenger. when muscarinic receptor bind to Acetylcholine it activate G protein couple receptor which activate second messenger guanylate cyclase which inhibit effect of cAMP and activates K+ channel which hyperpolarize cell and produce its effect. Cardiac activity is decreased in response to muscarinic receptor.
termination of Ach action:- acetylcholine receptor mainly found in parasympathomimetic nervous system. effect of cholinergic receptor when bound to acetylcholine is contraction of smooth muscle, decrease cardiac, dilate blood vessels output and increase body secretion.acetylcholine (Ach) activity gets terminated by enzyme acetylcholine esterase (AchE) which hydrolyase and degrade Ach. it is found in synaptic junction and in neuromuscular junction.