What is responsible for initiating contraction of smooth muscle?

Question

Quizplus · Accepted Answer

Smooth muscle contraction is initiated by automatic changes in ion movement across the membrane, leading to a drifting of the membrane potential towards threshold. This can be triggered by various factors, such as hormones or local chemical signals, and does not necessarily require input from the nervous system. While the autonomic nervous system can modulate smooth muscle contraction, it is not the primary initiator. Gap junctions can transmit electrical signals between smooth muscle cells, but they do not initiate contraction on their own. Inhibition of acetylcholinesterase would lead to increased levels of acetylcholine, which could potentially enhance the effect of nervous or chemical signals on smooth muscle contraction, but it is not the direct trigger.

What Is Responsible for Initiating Contraction of Smooth Muscle