Sequence of Muscle Contractions

Motor neuron stimulates neuromuscular junction.

step 1

Axon terminal's synaptic vesicles release acetylcholine into the synaptic cleft of the sarcolemma- causes electrical current.

step 2

Acetylcholine binds to its receptor on sarcolemma and opens K+/Na+ channels (action potential) causes SR to release Ca++

step 3

Ca++ binds to the T-T complex (troponin/tropomyosin)

step 4

myosin binding site opens up.

step 5

myosin grabs hold of actin (cross-bridge), actin slides over myosin.

step 6

ADP is released --> contraction occurs

step 7

Myosin releases actin, swivels back, binds and splits ATP

step 8

repeated binding of myosin with actin until ATP is gone.

step 9

Calcium is involved as a regulatory mechanism.

step 10

Acetylcholinesterase is always present to stop the drip of ACh

step 11

acetylcholine chemical formula

ACh

acetylcholinesterase chemical formula

AChE