11.2 Contraction of skeletal Muscle

Evidence For Sliding Filament Theory

• The I band becomes narrower.
• The Z lines move closer together/ the sarcommere shortens.
• The H zone gets narrower.

The A band remains the same length as it is determined by the length of the myosin, which according to this theory doesn't change size.

Muscle Stimulation

The action potential moves from the motor neurone into the muscle fibre as it would across a synapse.

Muscle Contraction

The action potential travels through the T-tubules in the sarcoplasm.

The endoplasmic reticulum is in contact with the sarcoplasm and has been in contact with the T-tubules and has actively absorbed calcium from the sarcoplasm.

The action potential causes calcium to diffuse into the…