KINE 2011 Chapter Notes - Chapter 9.3: Endoplasmic Reticulum, Dihydropyridine, Ford Power Stroke Engine
6 Jan 2018
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Reticulum: sarcoplasmic reticulum consists of interconnected compartments surrounding myofibril, sr wrap around a&i band, lateral sacs extending from t-tubules. Sacs store ca2+: ap down t-tubules releases ca2+ from sr to cytoplasm. Cytosolic calcium concentrations are low: ap results in rapid increase in cytosolic calcium concentrations, receptors on t-tubules called dihydropyridine receptors are voltage gated censored, foot proteins- calcium release channels, foot proteins on sr serve as calcium release channels. Foot proteins also called ryanodine receptors: foot proteins bind with receptors on t-tubules- called dihydropyridine receptors, when ap is propagated to t-tubules, receptors activates voltage-gated receptors. This trigger opening of ca2+ release channels in lateral sacs: calcium is released into cytosol. This repositions troponin & tropomyosin to allow binding of cross-bridge to actin. Atp-powered cross-bridge cycling power stroke: myosin has enzymatic site that binds adenosine triphosphate (atp) & splits into adp &
