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Chapter 15a

Chapter 15a. Blood Flow and the Control of Blood Pressure. About this Chapter. The blood vessels Blood pressure Resistance in the arterioles Distribution of blood to the tissues Exchange at the capillaries The lymphatic system Regulation of blood pressure Cardiovascular disease.

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Chapter 15a

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  1. Chapter 15a Blood Flow and the Control of Blood Pressure

  2. About this Chapter • The blood vessels • Blood pressure • Resistance in the arterioles • Distribution of blood to the tissues • Exchange at the capillaries • The lymphatic system • Regulation of blood pressure • Cardiovascular disease

  3. Functional Model of the Cardiovascular System Elastic arteries Aorta Aortic valve Left ventricle Left heart Mitral valve Arteriole withvariable radius Left atrium Pulmonary veins Exchange ofmaterial withcells Lungs Capillaries Pulmonary artery Pulmonary valve Venules Right ventricle Right heart Tricuspid valve Right atrium Venae cavae Expandable veins Figure 15-1

  4. Blood Vessel Structure Figure 15-2

  5. Blood Vessel Structure & Function PLAY Interactive Physiology® Animation:Cardiovascular System: Anatomy Review: Blood Vessel Structure & Function

  6. Metarterioles Regulate Flow into Capillary Beds • Capillaries lack smooth muscle and elastic tissue reinforcement, which facilitates exchange Vein Collateralarteries Venule Arteriole wall is smooth muscle. Metarterioles can act asbypass channels. Capillaries Smallvenule Precapillarysphincters Arteriovenousbypass Figure 15-3

  7. Angiogenesis • New blood vessel development • Necessary for normal development • Wound healing and uterine lining growth • Controlled by cytokines • Stimulate (mitogens): VEGF and FGF • Inhibit: angiostatin and endostatin • Coronary heart disease • Collateral circulation

  8. Elastic Recoil in Arteries 1 Ventricle contracts. Arterioles 2 Semilunar valve opens. 1 2 3 Aorta and arteries expand andstore pressure in elastic walls. 3 (a) Ventricular contraction Figure 15-4a

  9. Elastic Recoil in Arteries 1 Ventricle contracts. Arterioles 1 (a) Ventricular contraction Figure 15-4a, step 1

  10. Elastic Recoil in Arteries 1 Ventricle contracts. Arterioles 2 Semilunar valve opens. 1 2 (a) Ventricular contraction Figure 15-4a, steps 1–2

  11. Elastic Recoil in Arteries 1 Ventricle contracts. Arterioles 2 Semilunar valve opens. 1 2 3 Aorta and arteries expand andstore pressure in elastic walls. 3 (a) Ventricular contraction Figure 15-4a, steps 1–3

  12. Elastic Recoil in Arteries 1 Isovolumic ventricularrelaxation 2 Semilunar valve shuts, preventingflow back into ventricle. 1 2 3 Elastic recoil of arteries sendsblood forward into rest ofcirculatory system. 3 (b) Ventricular relaxation occurs. Figure 15-4b

  13. Elastic Recoil in Arteries 1 Isovolumic ventricularrelaxation 1 (b) Ventricular relaxation occurs. Figure 15-4b, step 1

  14. Elastic Recoil in Arteries 1 Isovolumic ventricularrelaxation 2 Semilunar valve shuts, preventingflow back into ventricle. 1 2 (b) Ventricular relaxation occurs. Figure 15-4a, steps 1–2

  15. Elastic Recoil in Arteries 1 Isovolumic ventricularrelaxation 2 Semilunar valve shuts, preventingflow back into ventricle. 1 2 3 Elastic recoil of arteries sendsblood forward into rest ofcirculatory system. 3 (b) Ventricular relaxation occurs. Figure 15-4a, steps 1–3

  16. Review of Blood Flow Table 15-1

  17. Pressure Throughout the Systemic Circulation • Blood pressure is highest in the arteries and decreases continuously as it flows through the circulatory system Figure 15-5

  18. Blood Pressure • Pulse Pressure = systolic P – diastolic P • Valves ensure one-way flow in veins • MAP = diastolic P + 1/3(systolic P – diastolic P) PLAY Interactive Physiology® Animation:Cardiovascular System: Measuring Blood Pressure

  19. Measurement of Arterial Blood Pressure (a) Cuff pressure> 120 mm Hg Inflatablecuff Pressuregauge (b) Cuff pressurebetween 80 and120 mm Hg Stethoscope (c) Cuff pressure< 80 mm Hg Figure 15-7

  20. Blood Pressure • Mean arterial pressure is a function of cardiac output and resistance in the arterioles Mean arterial pressure Cardiac output Variable resistance Arterioles Left ventricle Elastic arteries Mean arterial pressure  cardiac output  resistance Figure 15-8

  21. Blood Pressure • Blood pressure control includes rapid responses from the cardiovascular system and slower responses by the kidneys

  22. Blood Pressure Bloodvolume KEY Stimulus leads to Integrating center Bloodpressure Tissue response Systemic response triggers Fast response Slow response Compensationbycardiovascularsystem Compensationby kidneys Excretion of fluid in urineblood volume Vasodilation Cardiac output Bloodpressureto normal Figure 15-9

  23. Factors that Influence Mean Arterial Pressure Figure 15-10

  24. Factors that Influence Mean Arterial Pressure PLAY Interactive Physiology®Animation: Cardiovascular System: Factors That Affect Blood Pressure

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