Muscle Contraction Steps

Step 1

resting membrane potential: more potassium inside with a negative charge, more sodium outside with a positive charge

Step 2

brain signal travels along an axon to muscle cell

Step 3

calcium channels open and calcium diffuses into neuron

Step 4

synaptic vesicles fuse with membrane and release acetylcholine into synapse

Step 5

acetylcholine opens sodium channels and sodium diffuses into muscle cell (depolarization-positive charge inside)

Step 6

potassium channels open and potassium diffuses out of muscle cell (repolarization-negative charge inside)

Step 7

action potential travels along sarcolemma and t-tubules

Step 8

calcium channels open on the sarcoplasmic reticulum and calcium diffuses into cytoplasm of muscle cell

Step 9

calcium binds to troponin which pulls tropomyosin off of myosin binding sites on actin

Step 10

myosin binds and pulls on actin forming a cross-bridge

Step 11

atp binds to myosin releasing it from actin

Step 12

atp is hydrolized to adp+p energizing myosin for next pull on actin