https://stream.echo6.co/videos/watch/616b9964-f8da-43a6-8d28-fc072b33d8aa Official Ninja Nerd Website: https://ninjanerd.org Ninja Nerds! In this lecture, Professor Zach Murphy presents part 2 on the neuromuscular junction, focusing on excitation-contraction coupling. We begin by reviewing the depolarization of the muscle fiber following acetylcholine binding at the motor end plate, and trace the action potential as it propagates along the sarcolemma and into the transverse (T) tubules. This leads to activation of voltage-sensitive dihydropyridine receptors (DHPRs), which mechanically interact with ryanodine receptors (RyR1) in the sarcoplasmic reticulum, triggering the release of calcium ions into the cytosol. From here, we detail how calcium binds to troponin C, inducing a conformational shift that moves tropomyosin away from actin’s myosin-binding sites. This allows cross-bridge cycling as myosin heads attach to actin, perform the power stroke, and generate muscle contraction. We also discuss how ATP binding and hydrolysis are essential for both the detachment and re-cocking of myosin heads, ensuring continuous cycling as long as calcium and ATP are available. Finally, we explain the muscle relaxation process, where calcium is actively pumped back into the sarcoplasmic reticulum via SERCA pumps, restoring tropomyosin’s inhibitory position and ending contraction. Enjoy the lecture and support us below! 🌐 Official Links Website: https://www.ninjanerd.org Podcast: https://podcast.ninjanerd.org Store: https://merch.ninjanerd.org 📱 Social Media https://www.tiktok.com/@ninjanerdlectures https://www.instagram.com/ninjanerdlectures https://www.facebook.com/ninjanerdlectures https://x.com/ninjanerdsci/ https://www.linkedin.com/company/ninja-nerd/ 💬 Join Our Community Discord: https://discord.gg/3srTG4dngW #ninjanerd #NMJ #Musculoskeletal Mon, 13 Apr 2026 18:49:57 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://stream.echo6.co https://stream.echo6.co/client/assets/images/icons/icon-512x512.png https://stream.echo6.co/videos/watch/616b9964-f8da-43a6-8d28-fc072b33d8aa All rights reserved, unless otherwise specified in the terms specified at https://stream.echo6.co/about and potential licenses granted by each content's rightholder.