1.muscarinicreceptors:M,receptors:CNS neurons, sympathetic postganglionic neuronsM,receptors:myocardium,smooth muscleM,receptors:exocrine glands,vessels of the smooth muscle andendothelium2.nicotinicreceptors:N, receptors: ganglia and adrenal medullaN, receptors: skeletal muscle neuromuscular end-plates
1.muscarinic receptors: M1 receptors: CNS neurons, sympathetic postganglionic neurons M2 receptors: myocardium,smooth muscle M3 receptors: exocrine glands,vessels of the smooth muscle andendothelium 2.nicotinic receptors: N1 receptors: ganglia and adrenal medulla N2 receptors: skeletal muscle neuromuscular end-plates
IIthe cholinergicneuronA.Neurtransmission at cholinergic neuronsCholinergic transmissionl.Synthesisofacetylcholine:cholineCholine+acetyl-CoAacetylcholineacetyltransterase2.Storageofacetylcholineinvesicles
II the cholinergic neuron A. Neurtransmission at cholinergic neurons Cholinergic transmission 1.Synthesis of acetylcholine: Choline+acetyl-CoA acetylcholine 2.Storage of acetylcholine in vesicles choline acetyltransterase
3.Releaseofacetylcholine(exocytosis):When an action potential arrives at the nerve ending,calcium channels in the presynaptic membrane open,causing an increase in the concentration ofintracellularcalcium.Elevated calciumlevelspromote the fusion of synaptic vesicles with the cellmembrane(presynapticmembrane)andrelease ofacetylcholineinto the synaptic cleft
3. Release of acetylcholine (exocytosis) : When an action potential arrives at the nerve ending, calcium channels in the presynaptic membrane open, causing an increase in the concentration of intracellular calcium. Elevated calcium levels promote the fusion of synaptic vesicles with the cell membrane(presynaptic membrane) and release of acetylcholine into the synaptic cleft
4.Bindingto receptor:Afterrelease from the presynaptic terminal, acetylcholine maybind to and activate an acetylcholine receptor(cholinoceptor)5.Degradationofacetylcholine:acetylcholinesteraseAchcholine+acetic acidthe half-life of acetycholinein the synapseis very short
4. Binding to receptor: After release from the presynaptic terminal, acetylcholine may bind to and activate an acetylcholine receptor(cholinoceptor). 5. Degradation of acetylcholine: Ach choline + acetic acid the half-life of acetycholine in the synapse is very short. acetylcholinesterase
PresynapticaxonPresynapticaxonAcetylcholineAcetylcholinesteraseReceptorPostsynapticcellU0006000Postsynapticcell乙酰胆碱酯酶对乙酰胆碱的水解
乙酰胆碱酯酶对乙酰胆碱的水解