PHGY 214 Lecture Notes - Lecture 3: Adenosine, Membrane Potential, Angiotensin
12 May 2016
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When an artery reaches the organ it is supplying, it branches into numerous arterioles within the organ. Explain how arteriolar radius can change and what impact this would have on blood flow. Arterioles are the major resistance vessel in the vascular tree because their radius is small enough to offer considerable resistance to flow. Blood flow from the artery to the arterioles (a drop in mean pressure) helps establish the pressure differential that encourages the flow of blood from the heart to the various organs downstream. The radius can be adjusted independently to accomplish two functions: 1) to variably distribute the cardiac output among the systemic organs, depending on the body"s momentary needs; and 2) help regulate arterial blood pressure. A smaller radius increases surface area that comes in contact with blood. Decreasing radius by results in a 16-fold increase in resistance. Discuss the local chemical and physical influences on arteriolar radius.
