Steps in Muscle Contraction

Brain sends out a signal to the muscle

• Step 1

• Step 2

• Step 3

• Step 4

• Step 5

Motor neurons carry the signal to the skeletal muscle

• Step 1

• Step 2

• Step 3

• Step 4

• Step 5

Signal arrives at the neuromuscular junction

• Step 1

• Step 2

• Step 3

• Step 4

• Step 5

Action potential releases the ACh from the axon terminal

• Step 1

• Step 2

• Step 3

• Step 4

• Step 5

ACh moves across the synaptic cleft (open space) to bind to the receptors on the muscle cell (myofibril)

• Step 1

• Step 2

• Step 3

• Step 4

• Step 5

ACh on the muscle cells continue moving the action potential (signal) along the sarcolemma (membrane)

• Step 6

• Step 7

• Step 8

• Step 9

Action potential moves down the T-tubule

• Step 6

• Step 7

• Step 8

• Step 9

Action potential signals the sarcoplasmic reticulum to release the calcium (Ca2+) ions

• Step 6

• Step 7

• Step 8

• Step 9

calcium (Ca2+) ions cause the muscle to contract

• Step 6

• Step 7

• Step 8

• Step 9