myofibrils are surrounded by calcium- containing sarcoplasmic reticulum
Post on 21-Dec-2015
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![Page 1: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/1.jpg)
Myofibrils are surrounded by calcium-containing
sarcoplasmic reticulum.
![Page 2: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/2.jpg)
Review of thin and thick filament structure
![Page 3: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/3.jpg)
Overview of the process
![Page 4: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/4.jpg)
Overview of the process
The muscle fiber is stimulated.
![Page 5: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/5.jpg)
Overview of the process
The muscle fiber is stimulated.
Ca2+ ions are released.
![Page 6: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/6.jpg)
“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](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/7.jpg)
Fig. 6.24 also demonstrates this process.
![Page 8: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/8.jpg)
Overview of the process
The muscle fiber is stimulated.
Ca2+ ions are released.
![Page 9: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/9.jpg)
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](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/10.jpg)
Calcium attaches to troponin/ tropomyosin; they roll away, exposing the active site on actin.
![Page 11: Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/11.jpg)
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](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/12.jpg)
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](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/13.jpg)
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](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/14.jpg)
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](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/15.jpg)
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](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d575503460f94a36c6a/html5/thumbnails/16.jpg)
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.