Sarcomere Contraction

What is Rule # 1

An Action potential travels along an axon membrane to a neuromuscular junction

What is Rule # 2

CA²⁺ Channels open and CA²⁺ enters the presynaptic terminal

What is Rule # 3

Acetylcholine is released from presynaptic vesicles

What is Rule # 4

Acetylcholine stimulates Na⁺ Channels on the postsynaptic membrane to open

What is Rule # 5

Na⁺ diffuses into the muscle fiber, initiating an action potential that travels alng the sarcolemma and T-tubule membranes

What is Rule # 6

Action potentials in the T-tubules cause the sarcoplasmic reticulum to release Ca²⁺

What is Rule # 7

On the actin Ca²⁺ binds to troponin, which moves tropomyosin and exposes myosin attachment sites

What is Rule # 8

ATP molecules are broken down to ADP and P, which releases energy needed to move the myosin heads

What is Rule # 9

The heads of the myosin myofilaments bend, causing the actin to slide past the myosin. As long as Ca²⁺ is present, the cycle repeats