Chapter 20.2, Problem 15AYLO

Summary Introduction

To discuss:

Short- and long- term mechanisms of the local control of blood flow; examples of the vasoactive chemicals and how they can cause reactive hyperemia.

Introduction:

The narrowing of the vessel is called vasoconstriction, and the widening of the vessel is called vasodilation. These are the two ways to control the peripheral resistance. The widening of the vessel occurs as a result of muscular effect, and narrowing occurs as a result of the contraction of smooth muscle of the tunica media. The widening of the vessel in vasodilation is by muscular passivity rather than muscular effort. The smooth muscles get relaxed, and the blood pressure allows the vessel to expand. The vasoconstriction and vasodilation together is called as vasomotion. In the vasomotor center of the brain, the vasomotion is controlled by the nucleus of the medulla oblongata.