sliding filament theory

Draw sacromere at rest and contracted/eccentric, Outline the Process of sliding filament

Role of myosin + structure

Myosin forms a cross bridge attaching to actin when stimulated with calcium

• Thick protein filament contains cross bridges

Role of actin + structure

Binding site for the cross bridges when stimulated by the release of calcium to create movement

• Thin protein filament attached to Z line across the midline of sacromere

structure and roles of structures in Sarcomere

H zone: space between actin filament, shortens in contractions

I band: light band that contains the actin filament

A band: contains both thick and thin filaments and its thecentre of sacromere

Z line: Found at either end of sacromere, come closer togetherin concentric contractions and spread further when muscle relaxes in eecentric contraction

role of calcium

Release of ATP

Steps of sliding filament theory

1. Neurochemical stimulation release calcium into sarcomere

2. Causes actin filament to reveal a binding site for the myosin head to connect

3. Myosin head binds actin filaments creating cross bridge

4. Breakdown of ATP release energy to stimulate the myosin cross bridge to pull the actin filament towards the midline of the sarcomere

5. This reults in the shortening of the sarcomere as the actin and myosin filaments "slide over" eachother, causing the z lines come closer together and h zone shortens

6. Shortening each sarcromere shortens the myofibril resulting in the shorten of muscle fibres and movement occurs

7. Cross bridge attach and re-attach at different times to create movement and maintain tension

8. This process keeps repeating if the neural impulse is present or the muscle relaxes if neural impulse ends