During concentric isotonic contraction of a skeletal-muscle fiber, which of thes
ID: 174033 • Letter: D
Question
During concentric isotonic contraction of a skeletal-muscle fiber, which of these occurs? Sarcomeres lengthen A bands shorten I bands shorten A bands lengthen thin filaments shorten In skeletal muscle cells, calcium initiates contraction by binding to: tropomyosin. action. troponin. myosin. the thick filament. Which best describes "rigor mortis?" Lack of ATP following death causes cross-bridges to remain tightly bound to actin. Lack of ATP following death causes calcium to remain in the cytosol, continuously stimulating cross-bridge cycling. Repeated, high-frequency action potentials to a skeletal muscle fiber causes sustained contraction following death. Following death, calcium-activated proteases degrade all proteins in skeletal muscle fibers, making muscles limp. Build-up of K^+ in T-tubules causes constants of skeletal muscles that last for about 12 hours following death. Rigor mortis is caused by: buildup of lactic acid. lack of Ca^2+. depletion of glycogen. lack of ATP. deficient acetylcholine receptors.Explanation / Answer
6. I bands shorten
7. In skeletal muscle, calcium initiates contraction by binding to troponin, while in smooth muscle calcium initiates contraction by binding to calmodulin.
8. Lack of ATP following death causes cross-bridges to remain tightly bound to actin.
9. Lack of ATP.
10. MG is an autoimmune neuromuscular disorder. Autoimmune disorders occur when your immune system mistakenly attacks healthy tissue i.e., proteins that normally attack foreign, harmful substances in the body, attack the neurotransmitter substance acetylcholine, which is a crucial substance for communication between nerve cells and muscles. This results in muscle weakness.
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