1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Capillaries Artery: Tunica interna Tunica media Tunica externa Nerve Vein 1 mm (a) Vein Capillaries Artery 100 µm (b) a: ©The McGraw-Hill Companies, Inc.; b: ©Wolf H. Fahrenbach/Visuals Unlimited Fig. 20.1

2 Fig Lumen Tunica interna: Endothelium Basement membrane Tunica media Tunica externa Vasa vasorum Nerve Medium vein Tunica interna: Endothelium Basement membrane Valve Tunica media Tunica externa Tunica interna: Endothelium Basement membrane Tunica media Tunica externa Large vein Copyright © McGraw-Hill Education. Permission required for reproduction or display. Capillary Lumen Tunica interna: Endothelium Basement membrane Tunica media Tunica externa Vasa vasorum Nerve Tunica interna: Endothelium Basement membrane Tunica media Tunica externa Endothelium Basement membrane Tunica interna: Endothelium Basement membrane Internal elastic lamina Tunica media External elastic lamina Tunica externa VenuleArteriole Distributing (medium) artery Inferior vena cava Conducting (large) artery Direction of blood flow Aorta

3 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Carotid sinus (containing baroreceptors) Internal carotid artery Carotid body (containing chemoreceptors) External carotid artery Left common carotid artery Right common carotid artery Right subclavian artery Aortic arch Aortic bodies (containing chemoreceptors) Left subclavian artery Baroreceptors

4 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Pericyte Basal lamina Intercellular cleft Pinocytotic vesicle Endothelial cell Erythrocyte Tight junction

5 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Endothelial cells Erythrocyte Filtration pores (fenestrations) Basal lamina Intercellular cleft Nonfenestrated area 400 μm (b)(a) b: Courtesy of S. McNutt

6 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Macrophage Endothelial cells Erythrocytes in sinusoid Liver cell (hepatocyte) Microvilli Sinusoid

7 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Precapillary sphincters Metarteriole Thoroughfare channel Venule Capillaries (a) Sphincters open Arteriole VenuleArteriole (b) Sphincters closed Fig. 20.7

8 Distribution of Blood Pulmonary circuit 9% Heart 7% Veins 64% Systemic circuit 84% Arteries 15% Capillaries 5% Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display.

9 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. (a) Simplest pathway (1 capillary bed) (b) Portal system (2 capillary beds) (c) Arteriovenous anastomosis (shunt) (d) Venous anastomoses (e) Arterial anastomoses

10 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig Systolic pressure Diastolic pressure Increasing distance from left ventricle Systemic blood pressure (mm Hg) Aorta Large arteries Small arteries Arterioles Capillaries Venules Small veins Large veins Venae cavae

11 (a) (b) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig

12 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Externa Media Interna (a) Lumen (b) 30 µm a,b: Phelps, P. C. and Luft, J. H. (1969), “Electron microscopical study of relaxation and constriction in frog arterioles.” Am. J. Anat., 1969/125: 399–427. Reproduced with permission of Wiley Inc.

13 Table 20.1

14 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Elevated blood pressure Reduced blood pressure Arteries stretched Reduced heart rate Vasodilation Reduced vasomotor tone Baroreceptors increase firing rate Increased vagal tone Cardioinhibitory neurons stimulated Reduced sympathetic tone Vasomotor center is inhibited

15 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig Aorta Superior mesenteric artery Dilated Increased flow to intestines Constricted Reduced flow to intestines Common iliac arteries Constricted Reduced flow to legs Dilated Increased flow to legs (a)(b)

16 Fig Moderate exercise Total cardiac output 17.5 L/min. Other 400 mL/min. (2.3%) Coronary 750 mL/min. (4.3%) Cutaneous 1,900 mL/min. (10.9%) Cerebral 750 mL/min. (4.3%) Renal 600 mL/min. (3.4%) Digestive 600 mL/min. (3.4%) Muscular 12,500 mL/min. (71.4%) At rest Total cardiac output 5 L/min. Digestive 1,350 mL/min. (27.0%) Renal 1,100 mL/min. (22.0%) Cerebral 700 mL/min. (14.0%) Other 350 mL/min. (7.0%) Cutaneous 300 mL/min. (6.0%) Muscular 1,000 mL/min. (20.0%) Coronary 200 mL/min. (4.0%) Copyright © McGraw-Hill Education. Permission required for reproduction or display.

17 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Filtration pores Transcytosis Diffusion through endothelial cells Intercellular clefts

18 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig Arteriole Net filtration pressure: 13 out 33 out 20 in Net reabsorption pressure: 7 in 20 in 13 out Capillary Blood flow Arterial endForces (mm Hg)Venous end 30 out +3 out 33 out 28 in –8 out 20 in 13 out Hydrostatic pressures Blood hydrostatic pressure Interstitial hydrostatic pressure Net hydrostatic pressure Colloid osmotic pressures (COP) Blood Tissue fluid Oncotic pressure (net COP) Net filtration or reabsorption pressure 10 out +3 out 13 out 28 in –8 out 20 in 7 in Venule

19 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. To heart Valve open Venous blood Valve closed (a) Contracted skeletal muscles(b) Relaxed skeletal muscles