PHGY 214 Lecture Notes - Lecture 3: Vascular Resistance, Parasympathetic Nervous System, Smooth Muscle Tissue
15 Nov 2017
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Explain how arteriolar radius can change and what impact this would have on blood ow. Discuss local chemical and physical in uences on arteriolar radius. Describe sympathetic and parasympathetic control of arteriolar radius and how these interact with local chemical control. Describe concept of total peripheral resistance and discuss how local, nervous, and hormonal control of arteriolar radius may impact total peripheral resistance. Radius supplying individual organs can be adjusted independently to. Distribute cardiac output among systemic organs, depending on body"s momentary needs. Vasodilation: enlargement in circumference and radius of vessel. Results from relaxation of smooth muscle layer. Leads to decreased resistance and increased ow through vessel. Smaller radius increases sa that comes in contact with blood. Decreasing radius by results in 16 fold increase in resistance. Inherit tendency for membrane potential in smooth muscle cells to change so sometimes it will change gradually and aps re. Above are reasons for partial constriction at resting tone.
