The variable that causes a change in another?

Dependent Variable

Explanation: The dependent variable is the variable to be explained (the ‘effect”) and the independent variable is the variable expected to account for (the “cause” of) the dependent variable. Like Cause and Effect.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.