Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

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are surrounded by calcium- containing sarcoplasm ic reticulum.
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Transcript of Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Page 1: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Myofibrils are surrounded by calcium-containing

sarcoplasmic reticulum.

Page 2: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Review of thin and thick filament structure

Page 3: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Overview of the process

Page 4: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Overview of the process

The muscle fiber is stimulated.

Page 5: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Overview of the process

The muscle fiber is stimulated.

Ca2+ ions are released.

Page 6: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

“End-on” view of thick & thin filaments,

showing the effect of calcium ions after release

from the S.R.

Page 7: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Fig. 6.24 also demonstrates this process.

Page 8: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Overview of the process

The muscle fiber is stimulated.

Ca2+ ions are released.

Page 9: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Overview of the process

The muscle fiber is stimulated.

Ca2+ ions are released.

Thin filaments move to middle of sarcomere.

Page 10: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Calcium attaches to troponin/ tropomyosin; they roll away, exposing the active site on actin.

Page 11: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Myosin cross-bridges attach to active site on actin.

After attachment, the cross-bridges pivot, pulling the thin filaments.

Page 12: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

A fresh ATP replaces the ADP+Pi, allowing myosin and actin to detach.

Energy from the splitting of the fresh ATP allows repositioning of the myosin head.

Page 13: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

This leads back to Step 1, which continues the cycle as long as calcium ions are attached to troponin/tropomyosin.

Page 14: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Overview of the process

The muscle fiber is stimulated.

Ca2+ ions are released.

Thin filaments move to middle of sarcomere.

Page 15: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Overview of the process

The muscle fiber is stimulated.

Ca2+ ions are released.

Thin filaments move to middle of sarcomere.

Muscle fiber contracts.

Page 16: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum.

Overview of the process

The muscle fiber is stimulated.

Ca2+ ions are released.

Thin filaments move to middle of sarcomere.

Muscle fiber contracts.

Muscle tension increases.