All of the following is true about excitation contraction coupling in skeletal muscle, except:
Calcium binds to troponin C Ach is released at neuromuscular junction when action potential arrives at nerve terminal to produce end plate potential at post synaptic muscle membrane. Also, small quanta (packets) of acetylcholine are released randomly from the nerve cell membrane at rest. Each produces a minute depolarizing spike called a miniature endplate potential, which is about 0.5 mV in amplitude. Removal of troponin-tropomyosin complex from active site by calcium: Mechanism of Calcium removal that leads to relaxation Electromechanical coupling in skeletal muscle: Action potential causes mechanical change in DHPR receptor that opens RYR receptor of SERCA Electrochemical coupling in myocardium: AP causes opening of Ca++ channel associated with DHPR receptor. This calcium influx causes calcium induced calcium release from RYR.
Acetylcholine is released at nerve terminals
Ca++ is pumped backed into SERCA during relaxation
Ca++ is binds to tropomyosin to initiate contraction
Unlike cardiac muscle that has electrochemical coupling, skeletal muscle shows electromechanical coupling
Nerve Muscle Physiology