PPT Slide
Some differences between skeletal and smooth muscle cells:
Less total myofilaments, more actin:myosin myofilaments
Myofilaments are arranged in loose bundles
Calcium usually enters via extracellular fluid
No troponin/tropomyosin complex associated with actin fibers –calcium binds to a protein called calmodulin
When activated, calmodulin activates an enzyme: myosin kinase – causes ATP -> ADP + P P binds to head of myosin
Neurotransmitters – acetylcholine & norepinephrine
Hormones can initiate contraction