Question

Briefly describe the cascades for smooth muscle contraction and relaxation. Compare and contrast the role of Ca2+ in skeletal and smooth muscle contraction. Briefly describe why MLCK/MLCP activity is responsible for smooth muscle contraction vs. relaxation.

Answer 1

The smooth muscle has the lackness of striated cell pattern and also innervated by the autonomous nervous system.The cross bridge cycle of actin and myosin which develop a force also calcium initiate the contraction of muscle. The relaxation of smooth muscle occurs by the removal of the stimulus that contracts or by a action that directs the inhibition of contractile stimulus.

In smooth muscle contraction tge extracellular fluid most commonly rise the cytosolic Ca²⁺ and in skeletal muscle contraction the intracellular of sarcoplasmic reticulum will rise the cytosolic Ca²⁺.

The myosin light chain kinase (MLCK) is a phosphorylates control the contraction and it works when muscle contraction stimulated and that will increase the calcium ion concentration. In smooth muscle contraction the MLCK have decreased calcium concentration ion and increased phosphorylates to initiate relaxation.