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.
Smooth muscles are of two major types known as single unit, aka unitary, smooth muscles and multi-unit smooth muscles. The single unit smooth muscles contract and relax together, as the nerve impulse excites only one muscle cell, and that is passed on to other cells through gap junctions. Smooth muscles are found in inner organs while cardiac muscles are found only in the heart. â¢ Cardiac muscles are striated, but smooth muscles are non-striated. â¢ Each cardiac muscle cell has one or more nuclei, but the smooth muscle cells are single nucleated.