#NeuromuscularJunction #SynapticCleft #MyastheniaGravis
Neuromuscular Junction | Structure , Function & Diseases🩺
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▬▬▬▬▬▬▬▬▬▬ Contents of this video ▬▬▬▬▬▬▬▬▬▬
00:00:00 Neuromuscular Transmission & release of chemical neurotransmitter in Motor End Plate.
Conversion of Chemical message into Electrical message.
Neuro Muscular Junction (NMJ); defining & location.
"How the motor neurons talk to the muscles"
00:06:27 Neurotransmitters (NTs); their storage in Motor Nerve Ending (MNE).
Post-Synaptic membrane; definition of synapse.
Neuro Muscular Junction (NMJ); role as "chemical synapses".
Pre- and Post-Synaptic membrane; Pre synaptic membrane will "talk" and post-synaptic will "listen".
A "one-way" transmission not two-way; since only in one direction.
00:09:26 Acetylcholine (ACh); storage in vesicles.
Synthesis of Vesicles in Cell Body of neurons in the Spinal Cord; proteins as a principle only synthesized in neuronal cell bodies.
ACh synthesized in the Nerve Ending; Nerve Ending as a “semi-autonomous” unit; capable of NT synthesis.
00:16:14 Synthesis of Ach in detail; role of “Choline transporters”, Acetyl CoA & Choline Acetyl Transferase (CAT) enzyme.
Storage & concentration of of ACh in vesicles; stored as “chemical signaling molecules”.
00:21:53 1-Action Potential; its mechanism of generation & role of voltage-gated Na-channels; Na influx
2-Ca+ channels; role of “Ca-sensitive proteins”
3-Fusion of Vesicular membrane with pre-synaptic membrane triggered as a result of Ca influx; Ach release into the SYNAPTIC CLEFT; Exocytosis of Neurotransmitter.
SYNAPTOBREVIN & SYNTEXIN; role in Ach release.
Classification of above 3 as steps of PRE-SYNAPTIC EVENTS on NM Junction.
00:30:40 Movement of Ach from Pre-synaptic Membrane to Post-Synaptic Membrane (SYNAPTIC CLEFT) through diffusion.
ACh sensitive Receptors/channels on post-synaptic membrane; their role as “ears of the muscles”.
NICOTINIC CHOLINERGIC channels (NCC); Resting Membrane Potential (RMP) & importance of heavy Na+ influx in depolarization of post-synaptic membrane.
00:41:37 MOTOR-END PLATE (MEP) POTENTIAL & Miniature End Plate Potential concept.
MEP potential & Action Potential compared. Depolarization spreading to flanks of post-synaptic membrane.
Action Potential triggering in Voltage-gated Na+ channels in the flanks.
Reaching of Threshold Potential & spreading of wave of depolarization.
00:49:20 Revision of basic concept of NM Transmission at NMJ. "Talking" of neurons completed.
00:53:36 ACETYL-CHOLINESTERASES; their role in breaking of Ach; & termination of its action.
00:58:50 CLATHRINS proteins; vesicle formation role in recycling of choline.
01:01:15 MYASTHENIA GRAVIS: Autoantibodies attaching to Nicotinic Cholinergic Receptors (NCR) at NMJ.
NEUROMUSCULAR TRANSMISSION BLOCKADE due to Anti-cholinergic antibodies attaching at Nicotinic Cholinergic Receptors.
TREATMENT: Acetylcholinesterase inhibitor/blocker (AchI) resulting in increased no of Ach in NMJ.
Physostigmine, Neostigmine
01:09:11 EATON LAMBART MYASTHENIC SYNDROME; autoimmune disease; works by blocking Ca+ channels on pre-synaptic NMJ.
Differentiating b/w Myasthenia & Eaton Lambert: Weakness and/or difficulty in initiating movement in both.
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