Chapter 15 a Blood Flow and the Control

Chapter 15 a 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

Functional Model of the Cardiovascular System Elastic arteries Aorta Aortic valve Left ventricle Left heart Mitral valve Left atrium Arteriole with variable radius Pulmonary veins Lungs Exchange of material with cells Capillaries Pulmonary artery Pulmonary valve Right ventricle Right heart Venules Tricuspid valve Right atrium Venae cavae Expandable veins Figure 15 -1

Blood Vessel Structure Figure 15 -2

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

Metarterioles Regulate Flow into Capillary Beds • Capillaries lack smooth muscle and elastic tissue reinforcement, which facilitates exchange Collateral arteries Vein Venule Arteriole wall is smooth muscle. Metarterioles can act as bypass channels. Capillaries Small venule Precapillary sphincters Arteriovenous bypass Figure 15 -3

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

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

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

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

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

Elastic Recoil in Arteries 1 Isovolumic ventricular relaxation 1 2 Semilunar valve shuts, preventing flow back into ventricle. 3 Elastic recoil of arteries sends blood forward into rest of circulatory system. 2 3 (b) Ventricular relaxation occurs. Figure 15 -4 b

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

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

Elastic Recoil in Arteries 1 Isovolumic ventricular relaxation 1 2 Semilunar valve shuts, preventing flow back into ventricle. 3 Elastic recoil of arteries sends blood forward into rest of circulatory system. 2 3 (b) Ventricular relaxation occurs. Figure 15 -4 a, steps 1– 3

Review of Blood Flow Table 15 -1

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

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

Measurement of Arterial Blood Pressure (a) Cuff pressure > 120 mm Hg Inflatable cuff Pressure gauge (b) Stethoscope (c) Cuff pressure between 80 and 120 mm Hg Cuff pressure < 80 mm Hg Figure 15 -7

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

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

Blood Pressure Blood volume leads to KEY Stimulus Integrating center Blood pressure Tissue response Systemic response triggers Fast response Slow response Compensation by cardiovascular system Vasodilation Compensation by kidneys Excretion of fluid in urine blood volume Cardiac output Blood pressure to normal Figure 15 -9

Factors that Influence Mean Arterial Pressure Figure 15 -10

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