Final answer:
Smooth muscle cells are not typically chemically coupled by gap junctions. Gap junctions are found in cardiac and single-unit smooth muscle, allowing electrical signals to pass between cells and coordinate contraction. However, multiunit smooth muscle cells do not have gap junctions, limiting their ability to spread contraction.
Step-by-step explanation:
Smooth muscle cells are not typically chemically coupled by gap junctions. Gap junctions develop in the cardiac and single-unit smooth muscle during development, allowing electrical signals to pass efficiently between cells and coordinating contraction. However, multiunit smooth muscle cells, like those found in large blood vessels, the respiratory airways, and the eyes, rarely possess gap junctions, which means that contraction is confined to the stimulated cell and does not spread to neighboring cells.