ES 2100 Lecture Notes - Lecture 9: Addison-Wesley, Neuromuscular Junction, Atp Hydrolysis
Document Summary
Mechanical properties of a muscle are largely the result of the product of its constituent muscle fibers: The point at which the muscle attaches to the nerve ending. The impulse from motor neuron results in release of acetylcholine into neuromuscular junction and transmits action potential into the muscle fiber. Once that occurs, there is an influx of na+ (depolarization) and efflux of k+ (repolarization): Sodium travels into the muscle fiber while potassium travels out the muscle fiber. Action potential then propagates through the sarcolemma and causes the release of ca2+ from sr via calcium release channels (crc"s) Ca2+ binds to regulatory proteins (troponin), which subsequently changes its confirmation and moves another regulatory protein (tropomyosin), which exposes binding sites on the contractile protein actin. Muscles relax when no more calcium is being released. Increased atpase activity necessitates a rapid increase in the rate of atp production.
