Blood vessel diameter fluctuates between being constricted and being dilated. This is the primary contributor to blood pressure.
In order for blood vessels (arterioles) to maintain a steady pressure, there must be a prolonged presence of what ion in the smooth muscle cell's cytosol
In order for blood vessels to maintain a steady pressure, there must be a prolonged presence of CALCIUM ions in the smooth muscle cell's cytosol. This ion initiates smooth muscle contraction.
Arterioles are blood vessels that have muscular walls consisting of one or two layers of smooth muscle cells.
Calcium (Ca2+) ions start the contraction of the smooth muscle cells by binding to calmodulin protein and thereby activating myosin.
In consequence, Ca2+ ions act as a secondary messenger that activates calmodulin, stimulating the phosphorylation of the myosin light chain and thus triggering muscle contraction.
