Plateau

In the action potential graph of the smooth muscle there is a plateau. The plateau is related to the ion concentrations in and out of the cell. The concentrations can only change with the receptor channels. Everything that happens after the initial action potential is what later results in the prolonged contraction. The contraction is related to the myosin light chain. Both sodium and calcium channels are found in the muscle membrane. When a neurotransmitter or hormone binds to them, it opens the channels. This causes an influx of ions and activates the chain of events inside the muscle cell that lead to muscle contraction. Smooth muscle has way less sodium channels than skeletal muscle, but they are definitely there.