15 steps of muscle contraction

10

Myosin head remains bound to the actin until a new ATP molecule arrives

3

Sodium gates open- sodium ions enter through the channel into the muscle fiber

11

The new ATP causes the head to be released from the actin, prepares for the next power stroke.

6

The terminal cisternae (SR) release calcium ions into the sarcoplasm

15

The topomyosin shifts around to cover the myosin binding sites, the sarcomere slides back to the original position.

8

myosin head uses ATP and binds to actin to form a cross bridge

4

sodium ions cause a muscle action potential to occur along the sarcolemma

5

the muscle action potential continues down the sarcolemma to the T tubules

13

Calcium ions are actively transported back into the sarcoplasmic reticulum

7

Calcium ions bind to troponin causing a shift of the tropomyosin, exposing actin binding sites

14

Low calcium ion concentration in the sarcolplasm causes the ions to leave the tropnin

1

Motor neuron carries an impulse to the neuromuscular junction

2

Ach is released into the synaptic cleft and then binds to ACh receptors on the sarcolemma

12

ACh is destroyed by AChEsterase and the sarcolemma is no longer permeable

9

ADP +P is released and the myosin head flexes, causing the thin filament to move