Smooth muscle multiunit

Distinguish between multiunit smooth muscle and single-unit... 

Feature Skeletal muscle Multiunit smooth muscle Single unit smooth muscle... 

Multiunit smooth muscle is located in the large blood vessels, eyes (iris and ciliary muscle of the lens), and piloerector muscles at the base of hair follicles. This type of muscle consists of discrete smooth muscle cells or units that function independently. Each of these units is innervated by the... 

Many factors influence the contractile activity of smooth muscle. The strength of contraction of multiunit smooth muscle may be enhanced by stimulation of a greater number of cells, or contractile units. This mechanism is directly comparable to motor-unit recruitment employed by skeletal muscle. As the number of contracting muscle cells increases, so does the strength of contraction. However, this mechanism is of no value in single-unit smooth muscle. Due to the presence of gap junctions, all of the muscle cells in the tissue are activated at once. 

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