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In this IBDP Biology post, we will be learning about
- The striated muscle and sacromere structure
- Myofobrils
Striated Muscle Structure
- Muscles are attached to bones and move them
- Composed of
Muscle fibres: Bundles of muscle cells
- Muscle fibres are longer than typical cells
- Multinucleated
- Sacrolemma (single plasma membrane) surrounds each muscle fibre
- Sacroplasmic Reticulium: Conveys singal to contract all parts of muscle fibres at once and stores calcium
- Many Mitochondria between myofibrils to provide ATP for contractions
Myofibrils
Muscle fibres contain many myofibrils. The myobibrils have alternating light and dark bands
Myofibrils are made of:
- Repeating units of light and dark bands
- Z line in the centre of each light area
- Sacromere:
Functional unit of the myofibril. Part of the myofibril between one Z line and the next
The pattern of light and dark bands in sacromere is due to the arrangement of:
- Thin Actin Filaments
- Thick Myosin Filaments
Myosin Filaments:
- Occupy the centre of the sacromere
- Each myosin fillament forms
crossbridges with actin fillaments during muscle contraction
Structure of a Sacromere
- Myosin fibres: Thick with head-like structures
- Actin fibres: Thin
- Both are proteins
- Myosin cannot become shorter because it is one continuous protein
- Actin can slide towards the centre of the sacromere and therefore shortens
That's all for this blog post!
References:
- https://www.google.com/url?sa=i&url=https%3A%2F%2Ftraining.seer.cancer.gov%2Fanatomy%2Fmuscular%2Fstructure.html&psig=AOvVaw3KtCguqqpgjn554_QzTE_0&ust=1626450538369000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCJjdxMe25fECFQAAAAAdAAAAABAD
- https://lh4.googleusercontent.com/oJmqZpdr-IejkhGpDLsyN0HeFaGqJ0YXjmn8M48tFn36R-Qw3xowTwVTBSAibv7mTSy7II7IiJw26XiYrIRUwVSaB9IMFElzfETHVjtdLUgu7GpcFPe7E3yf5n7ZqzXW7eEaJMg
- https://www.google.com/url?sa=i&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FMyofibril&psig=AOvVaw14rJh891WxBNuaxbtG-BbP&ust=1626451262468000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCMiIuKC55fECFQAAAAAdAAAAABAU
Drafted by Venetia (Biology)