Blood flow through most organs is regulated primarily by increasing or decreasing the ________ activity to arteriolar smooth muscles in the organ.Another form of regulation,called ________,depends upon the metabolic activity of the organ.Increased activity leads to increased interstitial-fluid metabolites,which cause ________ of the arterioles.The former is a type of ________ regulation of blood flow; the latter is an example of ________ regulation.

Question

Quizplus · Accepted Answer

Blood flow through most organs is primarily regulated by the sympathetic activity to arteriolar smooth muscles in the organ. This is referred to as extrinsic regulation of blood flow. Another form of regulation is called active hyperemia, which depends upon the metabolic activity of the organ. Increased activity leads to increased interstitial-fluid metabolites, which cause dilation of the arterioles. This is an example of intrinsic regulation of blood flow. Reactive hyperemia is not involved in the regulation of blood flow, and parasympathetic activity generally leads to constriction rather than dilation. Therefore, option A is the best choice.

Blood Flow Through Most Organs Is Regulated Primarily by Increasing