Each physical or health hazard is a âhazard classâ (e.g., Carcinogenicity is a hazard class). A âhazard classâ may be sub-divided in the criteria into. several âhazard categoriesâ based on the degree of. severity of the hazard.
Quick Answer. Calcium is a crucial part of muscle contraction. The ionic element is released from muscles during contraction and relaxation. The release of calcium helps propagate the muscle contraction and relaxation stages. Continue Reading.
During contraction, the smooth-muscle cell's intermediate filaments help to draw the cell up, like closing a drawstring purse. Calcium ions regulate contraction in smooth muscle, but they do it in a slightly different way than in skeletal muscle: 1  Calcium ions come from outside of the cell.2  Calcium ions bind to an enzyme complex on myosin, called calmodulin-myosin light chain kinase.therwise, the chain of events that occurs in cardiac-muscle contraction is similar to that of skeletal muscle. Compared to skeletal muscle, smooth-muscle cells are small. They are spindle-shaped, about 50 to 200 microns long and only 2 to 10 microns in diameter.