浙江大学医学院：血管生理（PPT讲稿）Vascular Physiology

ascular Physiology ry shen(沈啸),MD Department of physiology Room 516, Research Building C School of Medicine, Zijingang Campus Email: shen@zju. edu. cr

Vascular Physiology Gregory Shen (沈啸), MD Department of Physiology Room 516, Research Building C School of Medicine, Zijingang Campus Email: shenx@zju.edu.cn 1

Tunica interna Valve Endothelium Subendothelial layer Internal elastic lamina Tunica media Smooth muscle External elastic lamina Tunica externa Adventitia Lumen Lumen Artery Capillary Vein network Endothelial cells Capillary

2 Tunica media Smooth muscle Tunica externa Adventitia

Endothelium elastic lamina Media External elastic lamina Adventia Normal Artery x Adventitia S Media < Intima

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Copymght e The McGraw-Hill Companies, nc. Permission requred for reproduction or display Vasa vasorum Nerve Tunica adventitia External elastic membrane Tunica Smooth muscle intima Internal elastic membrane Tunica Basement Lamina propria (smooth muscle media membrane and connective Endothelium tissue)

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Copyright e The McGraw-Hill Companies, Ine Permission required for reproduction or display TABLE 124 Functions of Endothelial Cells I. Serve as a physical lining that blood cells do not normally adhere to in heart and blood vessels 2. Serve as a permeability barrier for the exchange of nutrients, metabolic end products, and fluid between plasma and interstitial fluid; regulate transport of macromolecules and other substances 3. Secrete paracrine agents that act on adjacent vascular smooth muscle cells; including vasodilators--prostacyclin and nitric oxide(endothelium-derived relaxing factor, EDRF)and vasoconstrictors-notably endothelin-l 4. Mediate angiogenesis(new capillary growth). 5. Play a central role in vascular remodeling by detecting signals and releasing paracrine agents that act on adjacent ells in the blood vessel wall 6. Contribute to the formation and maintenance of extracellular matrix 7. Produce growth factors in response to damage 8. Secrete substances that regulate platelet clumping. clotting, and anticlotting 9. Synthesize active hormones from inactive precursors ( Chapter 14). 10. Extract or degrade hormones and other mediators ( Chapters 11, 13). 11. Secrete cytokines during immune responses( Chapter 18). 12. Influence vascular smooth-muscle proliferation in the disease atherosclerosis

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Elastic fibers Accounts for most of the stretch of vessels as well as other tissues( e. g. lungs) Composed of a core of elastin and a covering of microfibrils Covalently corss-link and assemble into a highly elastic network of fibers In arteries elastic fibers are arranged as concentric cylindrical lamellae

Elastic fibers • Accounts for most of the stretch of vessels as well as other tissues (e.g., lungs). • Composed of a core of elastin and a covering of microfibrils. • Covalently corss-link and assemble into a highly elastic network of fibers. • In arteries, elastic fibers are arranged as concentric cylindrical lamellae. 6

Collagen fibers Far less extensible than the elastic fibers The basic unit in blood vessels is composed of type and type ll collagen

Collagen fibers • Far less extensible than the elastic fibers. • The basic unit in blood vessels is composed of type I and type III collagen. 7

Aorta Medium Arteriole capillary artery painter True capilary Venule Vena cava radius 12 mm 2 mm 15 um 15 2.5 mm 15 mm thickness: 2 mm 1 m 20 um 30 um 2H 0.5 mm 1.5 mm Endotheli celis Elastic 8

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Because of the elastic properties of vessels, the pressure-flow relationship of passive vascular beds in non-linear △P Blood flow Resistance(r) aLI Dilated R= Rigid tub Autoregulating Constricted 06 200 Critical closing pressure Perfusion Pressure(mmHg) 9

Because of the elastic properties of vessels, the pressure-flow relationship of passive vascular beds in non-linear Blood flow = ΔP Resistance (R) R= 8Lη πr 4 Rigid tube 6 Critical closing pressure 9

Elastic and collagen fibers determine the distensibility/compliance of vessels Artery has low volume capacity but can withstand large transmural pressure difference. (resistance vessels Vein s have a large volume capacity but can withstand small transmural pressure differences. ( capacitance vessels Compliance c) △P Difference in compliance cause arteries to act as resistors and veins to act as capacitors

Elastic and collagen fibers determine the distensibility/compliance of vessels. • Artery has low volume capacity but can withstand large transmural pressure difference. (resistance vessels) • Vein s have a large volume capacity but can withstand small transmural pressure differences. (capacitance vessels) • Compliance (C) = • Difference in compliance cause arteries to act as resistors and veins to act as capacitors. ΔV ΔP 10