ANSC 3301 Lecture Notes - Lecture 17: Endoplasmic Reticulum, Muscarinic Acetylcholine Receptor, Troponin T
Document Summary
Motor unit- a muscle cell and all of the fibers that it innervates myofiber= muscle cell=myocyte. Associated with the sarcoplasmic reticulum (where all of the calcium is held) Terminal cisternae of sr: where t-tubules meet sarcoplasmic reticulum sarcoplasm= cytoplasm of muscle fibers. Action potential down to axon of a motor neuron. This causes a change in voltage (depolarization) which opens voltage-gated calcium channels. Calcium floods in and binds with a protein which causes vesicle fusion. This releases acetylcholine into the synaptic cleft. The neurotransmitter acts as a ligand binding to the nicotinic acetylcholine receptors (ion channels that is nonselective) [muscarinic are g coupled- not ion] This opens up a non-selective cation channel which allows for both sodium and potassium to move across the membrane and essential depolarize the cell. Membrane potential moves towards 0, depolarizing the end-plate (conductances are relatively 50/50)
