<prompt> Which of the following is NOT true for a smooth muscle?no Z-discs presentActin : myosin ratio 2 : 1The contraction is thick filament-drivenLatch bridge observed.  <response>: There are no Z-lines in smooth muscle. Z-lines are replaced with dense bodies. Thin : thick filament ratio is 15 : 1. When Ca2 combines with calmodulin, there is activation of the enzyme myosin light chain kinase MLCK, and the actin-myosin interaction can begin. Myosin light chains in the thick filament thus regulates the contraction. Latch-bridge phenomenon causes smooth muscle to develop sustained tension for a lesser energy consumption. 