The driving age should be raised up to 18 because teens can be a little careless. Driving at the age of 18 is a more mature age for teens because they can have more responsibility. Teens should not be driving at the age of 16 because they could be texting and driving or drinking and driving with some friends.
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: Calcium ions come from outside of the cell. Calcium ions bind to an enzyme complex on myosin, called calmodulin-myosin light chain kinase.
Electrical activitation of smooth muscle is passed from cell to cell by gap junctions. Smooth muscle of the gut can generate intrinsic rhythmic contraction, independent from direct neural control.Input from the autonomic nervous system increases or decreases the level of this spontaneous activity.mooth muscle ((unlike skeletal muscle) consists of individual cells (leiomyocytes), each cell with its own nucleus. The function of smooth muscle also differs substantially from that of striated muscle.