Impairment of intracellular calcium homeostasis in muscle fibers lead to chronic, severe muscle dysfunction. Impaired Calcium ATPase activity can lead to abnormal, persistent elevation of intracellular calcium concentrations. Explain how persistently high intracellular calcium concentration would affect cross-bridge formation, and muscle contractions, and muscle tension? (Mention the effects on the steps involved cross bridge formation, and muscle contraction/relaxation cycle, and overall muscle tension).
Impairment of intracellular calcium homeostasis in muscle fibers lead to chronic, severe muscle dysfunction. Impaired Calcium ATPase activity can lead to abnormal, persistent elevation of intracellular calcium concentrations. Explain how persistently high intracellular calcium concentration would affect cross-bridge formation, and muscle contractions, and muscle tension? (Mention the effects on the steps involved cross bridge formation, and muscle contraction/relaxation cycle, and overall muscle tension).
The sarcoplasmic reticulum(SR) regulates the amount of calcium in muscles. Following an increase in intracellular calcium levels, calcium binds to either troponin C on actin filaments (in striated muscle) or calmodulin (CaM), which controls myosin filaments (in smooth muscle). Calcium induces the troponin complex to move on actin filaments in striated muscle, exposing myosin-binding sites.
The power stroke that causes contraction is produced when ADP and inorganic phosphate (Pi) bound myosin can build cross-bridges with actin. This force shortens the muscle by causing the thin actin filament to move past the bulky myosin filament. Myosin is first bound to ATP, which releases it from actin, and myosin then hydrolyzes ATP to restart the process.
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