neuromuscular junction Flashcards
what do nerve signals triggers
muscle action potential
what are action potentials delivered by
motor neuron
how many fibers can a neurons trigger at one time
one or more
what is the result o a neuron plus a triggered fiber
motor unit
what is a neuromuscular junction
a neuronal ending to a muscle fiber
what do synaptic bulb ends do
release neurotransmitter
what is the muscle area of a neuromuscular junction called
motor end plate
what is the gap in a neuromuscular junction called
synaptic cleft
what is the sequence of events at the neuromuscular junction
1 release of neurotransmitter
2 diffuses across cleft
3 activation of receptors
4 generation of muscle action potential
what initates contraction
muscle action potential released
Ca2+ released from SR
4Ca2+ binds to troponin
moves tropomyosin off active sites
myosin binds to actin and starts contraction cycle
what happens during the contraction cycle
myosin binds to actin and releases phosphate group (forming crossbridge)
crossbridge swivels releasing ADP and shorting the sarcomere
ATP binds to myosin
ATP broken down to ADP and Pi
repeats
what happens to cause relaxation of muscles
the breakdown of ACh to stop muscle action
