12. Censored Image from Purves et al., Life: The Science of Biology , 4th Edition, by Sinauer Associates ( www.sinauer.com ) and WH Freeman ( www.whfreeman.com ), used with permission.
27. Autonomic nerve axon Gap junction/Nexus Myocyte plasmalemma + glycoprotein External lamina SMOOTH MUSCLE SMOOTH MUSCLE CELL has same contractile & control *machinery as skeletal myocyte, but less organized Reticular fiber Autonomic nerve axon Gap junction/Nexus Myocyte plasmalemma + glycoprotein External lamina * There is the important difference that smooth muscle uses Myosin Light-chain Kinase (MLCK) to phosphorylate the regulatory myson light chain as the main means to provoke the actomyosin ATPase to start contraction