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21 Blood Vessels and Circulation PowerPoint® Lecture Presentations prepared by Jason LaPres Lone Star College—North Harris © 2012 Pearson Education, Inc. An Introduction to Blood Vessels and Circulation • Learning Outcomes • 21-1 Distinguish among the types of blood vessels based on their structure and function, and describe how and where fluid and dissolved materials enter and leave the cardiovascular system. • 21-2 Explain the mechanisms that regulate blood flow through vessels, describe the factors that influence blood pressure, and discuss the mechanisms that regulate movement of fluids between capillaries and interstitial spaces. © 2012 Pearson Education, Inc. An Introduction to Blood Vessels and Circulation • Learning Outcomes • 21-3 Describe the control mechanisms that regulate blood flow and pressure in tissues, and explain how the activities of the cardiac, vasomotor, and respiratory centers are coordinated to control blood flow through the tissues. • 21-4 Explain the cardiovascular system’s homeostatic response to exercise and hemorrhaging, and identify the principal blood vessels and functional characteristics of the special circulation to the brain, heart, and lungs. © 2012 Pearson Education, Inc. An Introduction to Blood Vessels and Circulation • Learning Outcomes • 21-5 Describe the three general functional patterns seen in the pulmonary and systemic circuits of the cardiovascular system. • 21-6 Identify the major arteries and veins of the pulmonary circuit. • 21-7 Identify the major arteries and veins of the systemic circuit. © 2012 Pearson Education, Inc. An Introduction to Blood Vessels and Circulation • Learning Outcomes • 21-8 Identify the differences between fetal and adult circulation patterns, and describe the changes in the patterns of blood flow that occur at birth. • 21-9 Discuss the effects of aging on the cardiovascular system, and give examples of interactions between the cardiovascular system and other organ systems. © 2012 Pearson Education, Inc. An Introduction to Blood Vessels and Circulation • Blood Vessels • Are classified by size and histological organization • Are instrumental in overall cardiovascular regulation © 2012 Pearson Education, Inc. 21-1 Classes of Blood Vessels • Arteries • Carry blood away from heart • Arterioles • Are smallest branches of arteries • Capillaries • Are smallest blood vessels • Location of exchange between blood and interstitial fluid • Venules • Collect blood from capillaries • Veins • Return blood to heart © 2012 Pearson Education, Inc. 21-1 Blood Vessels • The Largest Blood Vessels • Attach to heart • Pulmonary trunk • Carries blood from right ventricle • To pulmonary circulation • Aorta • Carries blood from left ventricle • To systemic circulation © 2012 Pearson Education, Inc. 21-1 Blood Vessels • The Smallest Blood Vessels • Capillaries • Have small diameter and thin walls • Chemicals and gases diffuse across walls © 2012 Pearson Education, Inc. 21-1 Blood Vessels • The Structure of Vessel Walls • Walls have three layers 1. Tunica intima 2. Tunica media 3. Tunica externa © 2012 Pearson Education, Inc. 21-1 Blood Vessels • The Tunica Intima (Inner Layer) • Includes: • The endothelial lining • Connective tissue layer • Internal elastic membrane • In arteries, is a layer of elastic fibers in outer margin of tunica intima © 2012 Pearson Education, Inc. 21-1 Blood Vessels • The Tunica Media (Middle Layer) • Contains concentric sheets of smooth muscle in loose connective tissue • Binds to inner and outer layers • External elastic membrane of the tunica media • Separates tunica media from tunica externa © 2012 Pearson Education, Inc. 21-1 Blood Vessels • The Tunica Externa (Outer Layer) • Anchors vessel to adjacent tissues in arteries • Contains collagen fibers • Elastic fibers • In veins • Contains elastic fibers • Smooth muscle cells • Vasa vasorum (“vessels of vessels”) • Small arteries and veins • In walls of large arteries and veins • Supply cells of tunica media and tunica externa © 2012 Pearson Education, Inc. Figure 21-1 Comparisons of a Typical Artery and a Typical Vein Tunica externa Tunica media Tunica intima Smooth muscle Lumen of vein Internal elastic membrane External elastic membrane Endothelium Lumen of artery Elastic fiber ARTERY © 2012 Pearson Education, Inc. Artery and vein LM × 60 Figure 21-1 Comparisons of a Typical Artery and a Typical Vein Tunica externa Tunica media Tunica intima Lumen of vein Smooth muscle Lumen of artery Artery and vein © 2012 Pearson Education, Inc. Endothelium LM × 60 VEIN Table 21-1 Key Terms and Relationships Pertaining to Blood Circulation © 2012 Pearson Education, Inc. Table 21-1 Key Terms and Relationships Pertaining to Blood Circulation © 2012 Pearson Education, Inc. Table 21-1 Key Terms and Relationships Pertaining to Blood Circulation © 2012 Pearson Education, Inc. 21-1 Blood Vessels • Differences between Arteries and Veins • Arteries and veins run side by side • Arteries have thicker walls and higher blood pressure • Collapsed artery has small, round lumen (internal space) • Vein has a large, flat lumen • Vein lining contracts, artery lining does not • Artery lining folds • Arteries more elastic • Veins have valves © 2012 Pearson Education, Inc. 21-1 Structure and Function of Arteries • Arteries • Elasticity allows arteries to absorb pressure waves that come with each heartbeat • Contractility • Arteries change diameter • Controlled by sympathetic division of ANS • Vasoconstriction • The contraction of arterial smooth muscle by the ANS • Vasodilation • The relaxation of arterial smooth muscle • Enlarging the lumen © 2012 Pearson Education, Inc. 21-1 Structure and Function of Arteries • Vasoconstriction and Vasodilation • Affect: 1. Afterload on heart 2. Peripheral blood pressure 3. Capillary blood flow © 2012 Pearson Education, Inc. 21-1 Structure and Function of Arteries • Arteries • From heart to capillaries, arteries change • From elastic arteries • To muscular arteries • To arterioles © 2012 Pearson Education, Inc. 21-1 Structure and Function of Arteries • Elastic Arteries • Also called conducting arteries • Large vessels (e.g., pulmonary trunk and aorta) • Tunica media has many elastic fibers and few muscle cells • Elasticity evens out pulse force © 2012 Pearson Education, Inc. 21-1 Structure and Function of Arteries • Muscular Arteries • Also called distribution arteries • Are medium sized (most arteries) • Tunica media has many muscle cells © 2012 Pearson Education, Inc. 21-1 Structure and Function of Arteries • Arterioles • Are small • Have little or no tunica externa • Have thin or incomplete tunica media © 2012 Pearson Education, Inc. 21-1 Structure and Function of Arteries • Artery Diameter • Small muscular arteries and arterioles • Change with sympathetic or endocrine stimulation • Constricted arteries oppose blood flow • Resistance (R) • Resistance vessels - arterioles © 2012 Pearson Education, Inc. 21-1 Structure and Function of Arteries • Aneurysm • A bulge in an arterial wall • Is caused by weak spot in elastic fibers • Pressure may rupture vessel © 2012 Pearson Education, Inc. Figure 21-2 Histological Structure of Blood Vessels Large Vein Elastic Artery Internal elastic layer Endothelium Tunica intima Tunica externa Tunica media Tunica media Endothelium Tunica externa Tunica intima Muscular Artery Medium-Sized Vein Tunica externa Tunica externa Tunica media Tunica media Endothelium Endothelium Tunica intima Tunica intima Venule Arteriole Smooth muscle cells (Media) Tunica externa Endothelium Basement membrane Endothelium Fenestrated Capillary Capillaries Pores Endothelial cells Basement membrane © 2012 Pearson Education, Inc. Continuous Capillary Endothelial cells Basement membrane Figure 21-2 Histological Structure of Blood Vessels Large Vein Tunica externa Tunica media Endothelium Tunica intima Medium-Sized Vein Tunica externa Tunica media Endothelium Tunica intima Venule Tunica externa Endothelium © 2012 Pearson Education, Inc. Figure 21-2 Histological Structure of Blood Vessels Elastic Artery Internal elastic layer Endothelium Tunica intima Tunica media Tunica externa Muscular Artery Tunica externa Tunica media Endothelium Tunica intima Arteriole Smooth muscle cells (Media) Endothelium Basement membrane © 2012 Pearson Education, Inc. Figure 21-2 Histological Structure of Blood Vessels Fenestrated Capillary Pores Endothelial cells Basement membrane © 2012 Pearson Education, Inc. Capillaries Continuous Capillary Endothelial cells Basement membrane Figure 21-3a A Plaque within an Artery Tunica externa Lipid deposits (plaque) Tunica media Coronary artery LM × 6 A cross-sectional view of a large plaque © 2012 Pearson Education, Inc. Figure 21-3b A Plaque within an Artery Plaque deposit in vessel wall A section of a coronary artery narrowed by plaque formation © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Capillaries • Are smallest vessels with thin walls • Microscopic capillary networks permeate all active tissues • Capillary function • Location of all exchange functions of cardiovascular system • Materials diffuse between blood and interstitial fluid © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Capillary Structure • Endothelial tube, inside thin basement membrane • No tunica media • No tunica externa • Diameter is similar to red blood cell © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Continuous Capillaries • Have complete endothelial lining • Are found in all tissues except epithelia and cartilage • Functions of continuous capillaries • Permit diffusion of water, small solutes, and lipidsoluble materials • Block blood cells and plasma proteins © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Specialized Continuous Capillaries • Are in CNS and thymus • Have very restricted permeability • For example, the blood–brain barrier © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Fenestrated Capillaries • Have pores in endothelial lining • Permit rapid exchange of water and larger solutes between plasma and interstitial fluid • Are found in: • Choroid plexus • Endocrine organs • Kidneys • Intestinal tract © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Sinusoids (Sinusoidal Capillaries) • Have gaps between adjacent endothelial cells • Liver • Spleen • Bone marrow • Endocrine organs • Permit free exchange • Of water and large plasma proteins • Between blood and interstitial fluid • Phagocytic cells monitor blood at sinusoids © 2012 Pearson Education, Inc. Figure 21-4 Capillary Structure Basement membrane Endothelial cell Nucleus Endosomes Endosomes Basement membrane Fenestrations, or pores Boundary between endothelial cells Continuous capillary © 2012 Pearson Education, Inc. Boundary between endothelial cells Basement membrane Fenestrated capillary Gap between adjacent cells Sinusoid Figure 21-4a Capillary Structure Basement membrane Endothelial cell Nucleus Endosomes Basement membrane © 2012 Pearson Education, Inc. Boundary between endothelial cells Continuous capillary Figure 21-4b Capillary Structure Basement membrane Endothelial cell Nucleus Endosomes Fenestrations, or pores Boundary between endothelial cells Basement membrane Fenestrated capillary © 2012 Pearson Education, Inc. Figure 21-4c Capillary Structure Gap between adjacent cells Sinusoid © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Capillary Beds (Capillary Plexus) • Connect one arteriole and one venule • Precapillary Sphincter • Guards entrance to each capillary • Opens and closes, causing capillary blood to flow in pulses © 2012 Pearson Education, Inc. Figure 21-5a The Organization of a Capillary Bed Vein Smooth muscle cells Collateral arteries Venule Arteriole Thoroughfare channel Capillaries Metarterioles Section of precapillary sphincter Small venule Precapillary sphincters Arteriovenous anastomosis KEY Consistent blood flow Variable blood flow A typical capillary bed. Solid arrows indicate consistant blood flow; dashed arrows indicate variable or pulsating blood flow. © 2012 Pearson Education, Inc. Figure 21-5b The Organization of a Capillary Bed Small artery Arteriole Metarterioles Capillary bed LM × 125 Capillary beds A micrograph of a number of capillary beds. © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Thoroughfare Channels • Direct capillary connections between arterioles and venules • Controlled by smooth muscle segments (metarterioles) © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Collaterals • Multiple arteries that contribute to one capillary bed • Allow circulation if one artery is blocked • Arterial anastomosis • Fusion of two collateral arteries • Arteriovenous anastomoses • Direct connections between arterioles and venules • Bypass the capillary bed © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Angiogenesis • Formation of new blood vessels • Vascular endothelial growth factor (VEGF) • Occurs in the embryo as tissues and organs develop • Occurs in response to factors released by cells that are hypoxic, or oxygen-starved • Most important in cardiac muscle, where it takes place in response to a chronically constricted or occluded vessel © 2012 Pearson Education, Inc. 21-1 Structure and Function of Capillaries • Vasomotion • Contraction and relaxation cycle of capillary sphincters • Causes blood flow in capillary beds to constantly change routes © 2012 Pearson Education, Inc. 21-1 Structure and Function of Veins • Veins • Collect blood from capillaries in tissues and organs • Return blood to heart • Are larger in diameter than arteries • Have thinner walls than arteries • Have lower blood pressure © 2012 Pearson Education, Inc. 21-1 Structure and Function of Veins • Venules • Very small veins • Collect blood from capillaries • Medium-sized veins • Thin tunica media and few smooth muscle cells • Tunica externa with longitudinal bundles of elastic fibers © 2012 Pearson Education, Inc. 21-1 Structure and Function of Veins • Large Veins • Have all three tunica layers • Thick tunica externa • Thin tunica media • Venous Valves • Folds of tunica intima • Prevent blood from flowing backward • Compression pushes blood toward heart © 2012 Pearson Education, Inc. Figure 21-6 The Function of Valves in the Venous System Valve closed Valve opens above contracting muscle Valve closed Valve closes below contracting muscle © 2012 Pearson Education, Inc. 21-1 Blood Vessels • The Distribution of Blood • Heart, arteries, and capillaries • 30–35% of blood volume • Venous system • 60–65% • 1/3 of venous blood is in the large venous networks of the liver, bone marrow, and skin © 2012 Pearson Education, Inc. Figure 21-7 The Distribution of Blood in the Cardiovascular System P ns vei Heart 7% em ic 7% Sy st ies 2% llar s le rio te Ar art eri al sys tem Aorta 2% Ela stic Mu arte sc r i es ul 4% ar ar te rie s5 % ic em s 7% t s Sy larie il cap © 2012 Pearson Education, Inc. 4% 13% 3% ar te rie s 64 % m on ar y Pu l y 2% % ic venous sys t em System c r lm na Pu lmo u i cap mic ste Sy Venules and medium-sized veins 25% y ar on s rie a ill ap 7 Heart Large venous networks (liver, bone marrow, skin) 21% y ar on 9% lm it Pu ircu c Large veins 18% 21-1 Blood Vessels • Capacitance of a Blood Vessel • The ability to stretch • Relationship between blood volume and blood pressure • Veins (capacitance vessels) stretch more than arteries © 2012 Pearson Education, Inc. 21-1 Blood Vessels • Venous Response to Blood Loss • Vasomotor centers stimulate sympathetic nerves 1. Systemic veins constrict (venoconstriction) 2. Veins in liver, skin, and lungs redistribute venous reserve © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Total Capillary Blood Flow • Equals cardiac output • Is determined by: • Pressure (P) and resistance (R) in the cardiovascular system © 2012 Pearson Education, Inc. Figure 21-8 An Overview of Cardiovascular Physiology Cardiac Output Venous Return Arterial Blood Pressure Regulation (Neural and Hormonal) Venous Pressure Peripheral Resistance Capillary Pressure Capillary exchange Interstitial fluid © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Pressure (P) • The heart generates P to overcome resistance • Absolute pressure is less important than pressure gradient • The Pressure Gradient (∆P) • Circulatory pressure • The difference between: • Pressure at the heart • And pressure at peripheral capillary beds © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Flow (F) • Is proportional to the pressure difference (∆P) • Divided by R © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Measuring Pressure 1. Blood pressure (BP) • Arterial pressure (mm Hg) 1. Capillary hydrostatic pressure (CHP) • Pressure within the capillary beds 1. Venous pressure • Pressure in the venous system © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Circulatory Pressure • ∆P across the systemic circuit (about 100 mm Hg) • Circulatory pressure must overcome total peripheral resistance • R of entire cardiovascular system © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Total Peripheral Resistance • Vascular resistance • Blood viscosity • Turbulence © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Vascular Resistance • Due to friction between blood and vessel walls • Depends on vessel length and vessel diameter • Adult vessel length is constant • Vessel diameter varies by vasodilation and vasoconstriction • R increases exponentially as vessel diameter decreases © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Viscosity • R caused by molecules and suspended materials in a liquid • Whole blood viscosity is about four times that of water © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Turbulence • Swirling action that disturbs smooth flow of liquid • Occurs in heart chambers and great vessels • Atherosclerotic plaques cause abnormal turbulence © 2012 Pearson Education, Inc. Figure 21-9 Factors Affecting Friction and Vascular Resistance Friction and Vessel Length Internal surface area = 1 Resistance to flow = 1 Flow = 1 Resistance to flow = 2 Internal surface area = 2 Flow = 1/ 2 Friction and Vessel Diameter Greatest resistance, slowest flow near surfaces Least resistance, greatest flow at center Vessel Length versus Vessel Diameter Diameter = 2 cm Resistance to flow = 1 Diameter = 1 cm Resistance to flow = 16 Factors Affecting Vascular Resistance Plaque deposit © 2012 Pearson Education, Inc. Turbulence Turbulence Table 21-1 Key Terms and Relationships Pertaining to Blood Circulation © 2012 Pearson Education, Inc. Table 21-1 Key Terms and Relationships Pertaining to Blood Circulation © 2012 Pearson Education, Inc. Table 21-1 Key Terms and Relationships Pertaining to Blood Circulation © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • An Overview of Cardiovascular Pressures • Vessel diameters • Total cross-sectional areas • Pressures • Velocity of blood flow © 2012 Pearson Education, Inc. Figure 21-10a Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and Blood Velocity within the Systemic Circuit Vessel diameter (cm) Vessel diameter © 2012 Pearson Education, Inc. Figure 21-10b Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and Blood Velocity within the Systemic Circuit Crosssectional area (cm2) Total cross-sectional area of vessels © 2012 Pearson Education, Inc. Figure 21-10c Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and Blood Velocity within the Systemic Circuit Average blood pressure (mm Hg) Average blood pressure © 2012 Pearson Education, Inc. Figure 21-10d Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and Blood Velocity within the Systemic Circuit Velocity of blood flow (cm/sec) Velocity of blood flow © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Arterial Blood Pressure • Systolic pressure • Peak arterial pressure during ventricular systole • Diastolic pressure • Minimum arterial pressure during diastole © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Arterial Blood Pressure • Pulse pressure • Difference between systolic pressure and diastolic pressure • Mean arterial pressure (MAP) • MAP = diastolic pressure + 1/3 pulse pressure © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Abnormal Blood Pressure • Normal = 120/80 • Hypertension • Abnormally high blood pressure • Greater than 140/90 • Hypotension • Abnormally low blood pressure © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Elastic Rebound • Arterial walls • Stretch during systole • Rebound (recoil to original shape) during diastole • Keep blood moving during diastole © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Pressures in Small Arteries and Arterioles • Pressure and distance • MAP and pulse pressure decrease with distance from heart • Blood pressure decreases with friction • Pulse pressure decreases due to elastic rebound © 2012 Pearson Education, Inc. Figure 21-11 Pressures within the Systemic Circuit Systolic Pulse pressure Mean arterial pressure Diastolic mm Hg © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Venous Pressure and Venous Return • Determines the amount of blood arriving at right atrium each minute • Low effective pressure in venous system © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Venous Pressure and Venous Return • Low venous resistance is assisted by: • Muscular compression of peripheral veins • Compression of skeletal muscles pushes blood toward heart (one-way valves) • The respiratory pump • Thoracic cavity action • Inhaling decreases thoracic pressure • Exhaling raises thoracic pressure © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Capillary Pressures and Capillary Exchange • Vital to homeostasis • Moves materials across capillary walls by: • Diffusion • Filtration • Reabsorption © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Diffusion • Movement of ions or molecules • From high concentration • To lower concentration • Along the concentration gradient © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Diffusion Routes 1. Water, ions, and small molecules such as glucose • Diffuse between adjacent endothelial cells • Or through fenestrated capillaries 1. Some ions (Na+, K+, Ca2+, Cl−) • Diffuse through channels in plasma membranes © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Diffusion Routes 3. Large, water-soluble compounds • Pass through fenestrated capillaries 3. Lipids and lipid-soluble materials such as O2 and CO2 • Diffuse through endothelial plasma membranes 3. Plasma proteins • Cross endothelial lining in sinusoids © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Filtration • Driven by hydrostatic pressure • Water and small solutes forced through capillary wall • Leaves larger solutes in bloodstream © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Reabsorption • The result of osmotic pressure (OP) • Blood colloid osmotic pressure (BCOP) • Equals pressure required to prevent osmosis • Caused by suspended blood proteins that are too large to cross capillary walls © 2012 Pearson Education, Inc. Figure 21-12 Capillary Filtration Capillary hydrostatic pressure (CHP) Amino acid Blood protein Glucose Ions Interstitial fluid Small solutes Hydrogen bond Water molecule Endothelial cell 1 © 2012 Pearson Education, Inc. Endothelial cell 2 21-2 Pressure and Resistance • Interplay between Filtration and Reabsorption 1. Ensures that plasma and interstitial fluid are in constant communication and mutual exchange 2. Accelerates distribution of: • Nutrients, hormones, and dissolved gases throughout tissues © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Interplay between Filtration and Reabsorption 3. Assists in the transport of: • Insoluble lipids and tissue proteins that cannot enter bloodstream by crossing capillary walls 4. Has a flushing action that carries bacterial toxins and other chemical stimuli to: • Lymphatic tissues and organs responsible for providing immunity to disease © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Interplay between Filtration and Reabsorption • Net hydrostatic pressure • Forces water out of solution • Net osmotic pressure • Forces water into solution • Both control filtration and reabsorption through capillaries © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Factors that Contribute to Net Hydrostatic Pressure 1. Capillary hydrostatic pressure (CHP) 2. Interstitial fluid hydrostatic pressure (IHP) • Net capillary hydrostatic pressure tends to push water and solutes: • Out of capillaries • Into interstitial fluid © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Net Capillary Colloid Osmotic Pressure • Is the difference between: 1. Blood colloid osmotic pressure (BCOP) 2. Interstitial fluid colloid osmotic pressure (ICOP) • Pulls water and solutes: • Into a capillary • From interstitial fluid © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Net Filtration Pressure (NFP) • The difference between: • Net hydrostatic pressure • Net osmotic pressure NFP = (CHP – IHP) – (BCOP – ICOP) © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Capillary Exchange • At arterial end of capillary: • Fluid moves out of capillary • Into interstitial fluid • At venous end of capillary: • Fluid moves into capillary • Out of interstitial fluid © 2012 Pearson Education, Inc. 21-2 Pressure and Resistance • Capillary Exchange • Transition point between filtration and reabsorption • Is closer to venous end than arterial end • Capillaries filter more than they reabsorb • Excess fluid enters lymphatic vessels © 2012 Pearson Education, Inc. Figure 21-13 Forces Acting across Capillary Walls KEY CHP (Capillary hydrostatic pressure) BCOP (Blood colloid osmotic pressure) Arteriole NFP (Net filtration pressure) Filtration 24 L/day 35 mm Hg 25 mm Hg NFP = +10 mm Hg CHP > BCOP Fluid forced out of capillary © 2012 Pearson Education, Inc. No net fluid movement 25 mm Hg Reabsorption 20.4 L/day 18 25 mm mm Hg Hg 25 mm Hg NFP = 0 Venule NFP = −7 mm Hg CHP = BCOP No net movement of fluid BCOP > CHP Fluid moves into capillary 21-2 Pressure and Resistance • Capillary Dynamics • Hemorrhaging • Reduces CHP and NFP • Increases reabsorption of interstitial fluid (recall of fluids) • Dehydration • Increases BCOP • Accelerates reabsorption • Increase in CHP or BCOP • Fluid moves out of blood • Builds up in peripheral tissues (edema) © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Tissue Perfusion • Blood flow through the tissues • Carries O2 and nutrients to tissues and organs • Carries CO2 and wastes away • Is affected by: 1. Cardiac output 2. Peripheral resistance 3. Blood pressure © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Cardiovascular Regulation Changes Blood Flow to a Specific Area 1. At an appropriate time 2. In the right area 3. Without changing blood pressure and blood flow to vital organs © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Controlling Cardiac Output and Blood Pressure • Autoregulation • Causes immediate, localized homeostatic adjustments • Neural mechanisms • Respond quickly to changes at specific sites • Endocrine mechanisms • Direct long-term changes © 2012 Pearson Education, Inc. Figure 21-14 Short-Term and Long-Term Cardiovascular Responses Autoregulation Autoregulation is due to opening and closing precapillary sphincters due to local release of vasodilator or vasoconstrictor chemicals from the tissue. HOMEOSTASIS RESTORED Local decrease in resistance and increase in blood flow HOMEOSTASIS Local vasodilators released Inadequate local blood pressure and blood flow HOMEOSTASIS DISTURBED • Physical stress (trauma, high temperature) • Chemical changes (decreased O2 or pH, increased CO2 or prostaglandins) • Increased tissue activity © 2012 Pearson Education, Inc. Normal blood pressure and volume Start Figure 21-14 Short-Term and Long-Term Cardiovascular Responses Central Regulation Central regulation involves neuroendocrine mechanisms that control the total systemic circulation. This regulation involves both the cardiovascular centers and the vasomotor centers. Neural mechanisms Stimulation of receptors sensitive to changes in systemic blood pressure or chemistry Stimulation of endocrine response Activation of cardiovascular centers Short-term elevation of blood pressure by sympathetic stimulation of the heart and peripheral vasoconstriction Long-term increase in blood volume and blood pressure Endocrine mechanisms If autoregulation is ineffective HOMEOSTASIS RESTORED © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Autoregulation of Blood Flow within Tissues • Adjusted by peripheral resistance while cardiac output stays the same • Local vasodilators accelerate blood flow at tissue level • Low O2 or high CO2 levels • Low pH (acids) • Nitric oxide (NO) • High K+ or H+ concentrations • Chemicals released by inflammation (histamine) • Elevated local temperature © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Autoregulation of Blood Flow within Tissues • Adjusted by peripheral resistance while cardiac output stays the same • Local vasoconstrictors • Examples: prostaglandins and thromboxanes • Released by damaged tissues • Constrict precapillary sphincters • Affect a single capillary bed © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Neural Mechanisms • Cardiovascular (CV) centers of the medulla oblongata • Cardiac centers • Cardioacceleratory center increases cardiac output • Cardioinhibitory center reduces cardiac output © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Vasomotor Center 1. Control of vasoconstriction • Controlled by adrenergic nerves (NE) • Stimulates smooth muscle contraction in arteriole walls 1. Control of vasodilation • Controlled by cholinergic nerves (NO) • Relaxes smooth muscle • Vasomotor Tone • Produced by constant action of sympathetic vasoconstrictor nerves © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Reflex Control of Cardiovascular Function • Cardiovascular centers monitor arterial blood • Baroreceptor reflexes • Respond to changes in blood pressure • Chemoreceptor reflexes • Respond to changes in chemical composition, particularly pH and dissolved gases © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Baroreceptor Reflexes • Stretch receptors in walls of: 1. Carotid sinuses (maintain blood flow to brain) 2. Aortic sinuses (monitor start of systemic circuit) 3. Right atrium (monitors end of systemic circuit) © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Baroreceptor Reflexes • When blood pressure rises, CV centers: 1. Decrease cardiac output 2. Cause peripheral vasodilation • When blood pressure falls, CV centers: 1. Increase cardiac output 2. Cause peripheral vasoconstriction © 2012 Pearson Education, Inc. Figure 21-15 Baroreceptor Reflexes of the Carotid and Aortic Sinuses Cardioinhibitory centers stimulated Cardioacceleratory centers inhibited Responses to Increased Baroreceptor Stimulation Decreased cardiac output Vasomotor centers inhibited Baroreceptors stimulated Vasodilation occurs HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Rising blood pressure Blood pressure declines Start HOMEOSTASIS Normal range of blood pressure © 2012 Pearson Education, Inc. Figure 21-15 Baroreceptor Reflexes of the Carotid and Aortic Sinuses HOMEOSTASIS Start Normal range of blood pressure HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Falling blood pressure Blood pressure rises Vasoconstriction occurs Baroreceptors inhibited Vasomotor centers stimulated Responses to Decreased Baroreceptor Stimulation Cardioacceleratory centers stimulated Cardioinhibitory centers inhibited © 2012 Pearson Education, Inc. Increased cardiac output 21-3 Cardiovascular Regulation • Chemoreceptor Reflexes • Peripheral chemoreceptors in carotid bodies and aortic bodies monitor blood • Central chemoreceptors below medulla oblongata: • Monitor cerebrospinal fluid • Control respiratory function • Control blood flow to brain © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Chemoreceptor Reflexes • Changes in pH, O2, and CO2 concentrations • Produced by coordinating cardiovascular and respiratory activities © 2012 Pearson Education, Inc. Figure 21-16 The Chemoreceptor Reflexes Respiratory centers in the medulla oblongata stimulated Increasing CO2 levels, decreasing pH and O2 levels Effects on Cardiovascular Centers Reflex Response Chemoreceptors stimulated Respiratory Response Respiratory rate increases Cardiovascular Responses Cardioacceleratory centers stimulated Increased cardiac output and blood pressure Cardioinhibitory centers inhibited Vasomotor centers stimulated Start Vasoconstriction occurs HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Elevated CO2 levels, decreased pH and O2 levels in blood and CSF Decreased CO2 levels, increased pH and O2 levels in blood and CSF HOMEOSTASIS Normal pH, O2, and CO2 levels in blood and CSF © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • CNS Activities and the Cardiovascular Centers • Thought processes and emotional states can elevate blood pressure by: • Cardiac stimulation and vasoconstriction © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Hormones and Cardiovascular Regulation • Hormones have short-term and long-term effects on cardiovascular regulation • For example, E and NE from adrenal medullae stimulate cardiac output and peripheral vasoconstriction © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Antidiuretic Hormone (ADH) • Released by neurohypophysis (posterior lobe of pituitary) • Elevates blood pressure • Reduces water loss at kidneys • ADH responds to: • Low blood volume • High plasma osmotic concentration • Circulating angiotensin II © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Angiotensin II • Responds to fall in renal blood pressure • Stimulates: 1. Aldosterone production 2. ADH production 3. Thirst 4. Cardiac output and peripheral vasoconstriction © 2012 Pearson Education, Inc. 21-3 Cardiovascular Regulation • Erythropoietin (EPO) • Released at kidneys • Responds to low blood pressure, low O2 content in blood • Stimulates red blood cell production © 2012 Pearson Education, Inc. Figure 21-17a The Hormonal Regulation of Blood Pressure and Blood Volume HOMEOSTASIS Start Normal blood pressure and volume HOMEOSTASIS DISTURBED Blood pressure and volume fall Blood pressure and volume rise Decreasing blood Short-term pressure and Long-term volume Combined Short-Term and Long-Term Effects Sympathetic activation and release of adrenal hormones E and NE Endocrine Response of Kidneys Erythropoietin (EPO) is released Increased blood pressure Increased cardiac output and peripheral vasoconstriction Renin release leads to angiotensin II activation An g i ot en Angiotensin II Effects sinAntidiuretic II hormone released Aldosterone secreted Factors that compensate for decreased blood pressure and volume © 2012 Pearson Education, Inc. HOMEOSTASIS RESTORED Thirst stimulated Increased red blood cell formation Increased blood volume 21-3 Cardiovascular Regulation • Natriuretic Peptides • Atrial natriuretic peptide (ANP) • Produced by cells in right atrium • Brain natriuretic peptide (BNP) • Produced by ventricular muscle cells • Respond to excessive diastolic stretching • Lower blood volume and blood pressure • Reduce stress on heart © 2012 Pearson Education, Inc. Figure 21-17b The Hormonal Regulation of Blood Pressure and Blood Volume Responses to ANP and BNP Increased Na+ loss in urine Increased water loss in urine Natriuretic peptides released by the heart Reduced thirst Combined Effects Inhibition of ADH, aldosterone, epinephrine, Reduced blood volume and norepinephrine release Peripheral vasodilation HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Rising blood pressure and volume Declining blood pressure and volume Increasing blood pressure and volume Factors that compensate for increased blood pressure and volume © 2012 Pearson Education, Inc. HOMEOSTASIS Normal blood pressure and volume 21-4 Cardiovascular Adaptation • Blood, Heart, and Cardiovascular System • Work together as unit • Respond to physical and physiological changes (for example, exercise and blood loss) • Maintain homeostasis © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • The Cardiovascular Response to Exercise • Light Exercise • Extensive vasodilation occurs increasing circulation • Venous return increases with muscle contractions • Cardiac output rises 1. Venous return (Frank–Starling principle) 2. Atrial stretching © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • The Cardiovascular Response to Exercise • Heavy Exercise • Activates sympathetic nervous system • Cardiac output increases to maximum • About four times resting level • Restricts blood flow to “nonessential” organs (e.g., digestive system) • Redirects blood flow to skeletal muscles, lungs, and heart • Blood supply to brain is unaffected © 2012 Pearson Education, Inc. Table 21-2 Changes in Blood Distribution during Exercise © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Exercise, Cardiovascular Fitness, and Health • Regular moderate exercise • Lowers total blood cholesterol levels • Intense exercise • Can cause severe physiological stress © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation Table 21-3 Effects of Training on Cardiovascular Performance Subject Heart Stroke Weight (g) Volume (mL) Heart Rate (BPM) Cardiac Blood Pressure Output (systolic/ (L/min) diastolic) Nonathlete (rest) 300 60 83 5.0 120/80 104 192 19.9 187/75 100 53 5.3 120/80 167 182 30.4 200/90* Nonathlete (maximum) Trained athlete (rest) Trained athlete (maximum) 500 *Diastolic pressures of athletes during maximum activity have not been accurately measured. © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • The Cardiovascular Response to Hemorrhaging • Entire cardiovascular system adjusts to: • Maintain blood pressure • Restore blood volume © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Short-Term Elevation of Blood Pressure • Carotid and aortic reflexes • Increase cardiac output (increasing heart rate) • Cause peripheral vasoconstriction • Sympathetic nervous system • Triggers hypothalamus • Further constricts arterioles • Venoconstriction improves venous return © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Short-Term Elevation of Blood Pressure • Hormonal effects • Increase cardiac output • Increase peripheral vasoconstriction (E, NE, ADH, angiotensin II) © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Shock • Short-term responses compensate after blood losses of up to 20% of total blood volume • Failure to restore blood pressure results in shock © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Long-Term Restoration of Blood Volume • Recall of fluids from interstitial spaces • Aldosterone and ADH promote fluid retention and reabsorption • Thirst increases • Erythropoietin stimulates red blood cell production © 2012 Pearson Education, Inc. Figure 21-18 Cardiovascular Responses to Hemorrhaging and Blood Loss HOMEOSTASIS Normal blood pressure and volume HOMEOSTASIS DISTURBED Blood pressure and volume rise Extensive bleeding reduces blood pressure and volume Falling blood pressure and volume Elevation of blood volume Responses coordinated by the endocrine system Responses directed by the nervous system Pain, stress, anxiety, fear Long-Term Hormonal Response Cardiovascular Responses ADH, angiotensin II, aldosterone, and EPO released Peripheral vasoconstriction; mobilization of venous reserve Stimulation of baroreceptors and chemoreceptors Higher Centers Stimulation of cardiovascular centers © 2012 Pearson Education, Inc. HOMEOSTASIS RESTORED General sympathetic activation Increased cardiac output 21-4 Cardiovascular Adaptation • Vascular Supply to Special Regions • Through organs with separate mechanisms to control blood flow • Three important examples 1. Brain 2. Heart 3. Lungs © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Blood Flow to the Brain • Is top priority • Brain has high oxygen demand • When peripheral vessels constrict, cerebral vessels dilate, normalizing blood flow © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Stroke • Also called cerebrovascular accident (CVA) • Blockage or rupture in a cerebral artery • Stops blood flow © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Blood Flow to the Heart • Through coronary arteries • Oxygen demand increases with activity • Lactic acid and low O2 levels • Dilate coronary vessels • Increase coronary blood flow © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Blood Flow to the Heart • Epinephrine • Dilates coronary vessels • Increases heart rate • Strengthens contractions © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Heart Attack • A blockage of coronary blood flow • Can cause: • Angina (chest pain) • Tissue damage • Heart failure • Death © 2012 Pearson Education, Inc. 21-4 Cardiovascular Adaptation • Blood Flow to the Lungs • Regulated by O2 levels in alveoli • High O2 content • Vessels dilate • Low O2 content • Vessels constrict © 2012 Pearson Education, Inc. 21-5 Pulmonary and Systemic Patterns • Three General Functional Patterns 1. Peripheral artery and vein distribution is the same on right and left, except near the heart 2. The same vessel may have different names in different locations 3. Tissues and organs usually have multiple arteries and veins • Vessels may be interconnected with anastomoses © 2012 Pearson Education, Inc. Figure 21-19 A Schematic Overview of the Pattern of Circulation Brain Upper limbs Pulmonary circuit (veins) Lungs LA Left ventricle Systemic circuit (arteries) Kidneys Spleen Liver Digestive organs Gonads Lower limbs © 2012 Pearson Education, Inc. Figure 21-19 A Schematic Overview of the Pattern of Circulation Brain Upper limbs Pulmonary circuit (arteries) Lungs RA Systemic circuit (veins) Right ventricle Kidneys Liver Digestive organs Gonads Lower limbs © 2012 Pearson Education, Inc. 21-6 The Pulmonary Circuit • Deoxygenated Blood Arrives at Heart from Systemic Circuit • Passes through right atrium and right ventricle • Enters pulmonary trunk • At the lungs • CO2 is removed • O2 is added • Oxygenated blood • Returns to the heart • Is distributed to systemic circuit © 2012 Pearson Education, Inc. 21-6 The Pulmonary Circuit • Pulmonary Vessels • Pulmonary arteries • Carry deoxygenated blood • Pulmonary trunk • Branches to left and right pulmonary arteries • Pulmonary arteries • Branch into pulmonary arterioles • Pulmonary arterioles • Branch into capillary networks that surround alveoli © 2012 Pearson Education, Inc. 21-6 The Pulmonary Circuit • Pulmonary Vessels • Pulmonary veins • Carry oxygenated blood • Capillary networks around alveoli • Join to form venules • Venules • Join to form four pulmonary veins • Pulmonary veins • Empty into left atrium © 2012 Pearson Education, Inc. Figure 21-20 The Pulmonary Circuit Ascending aorta Superior vena cava Right lung Right pulmonary arteries Right pulmonary veins Inferior vena cava © 2012 Pearson Education, Inc. Descending aorta Figure 21-20 The Pulmonary Circuit Aortic arch Pulmonary trunk Left lung Left pulmonary arteries Left pulmonary veins Alveolus Capillary CO2 © 2012 Pearson Education, Inc. O2 21-7 The Systemic Circuit • The Systemic Circuit • Contains 84% of blood volume • Supplies entire body • Except for pulmonary circuit © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Systemic Arteries • Blood moves from left ventricle • Into ascending aorta • Coronary arteries • Branch from aortic sinus © 2012 Pearson Education, Inc. Figure 21-21 An Overview of the Major Systemic Arteries Vertebral Right common carotid Left common carotid Left subclavian Right subclavian Brachiocephalic trunk Axillary Aortic arch Ascending aorta Pulmonary trunk Descending aorta Diaphragm Celiac trunk Brachial Renal Superior mesenteric Gonadal Inferior mesenteric Common iliac Radial Ulnar Internal iliac External iliac Palmar arches Deep femoral Femoral © 2012 Pearson Education, Inc. Figure 21-21 An Overview of the Major Systemic Arteries Femoral Popliteal Descending genicular Posterior tibial Anterior tibial Fibular Dorsalis pedis Plantar arch © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The Aorta • The ascending aorta • Rises from the left ventricle • Curves to form aortic arch • Turns downward to become descending aorta © 2012 Pearson Education, Inc. Figure 21-22a Arteries of the Chest and Upper Limb Suprascapular Thyrocervical trunk Right subclavian Thoracoacromial Axillary Right common carotid Left common carotid Vertebral Brachiocephalic trunk Left subclavian Lateral thoracic Anterior humeral circumflex Aortic arch Ascending aorta Thoracic aorta Posterior humeral circumflex Subscapular Heart Deep brachial Intercostal arteries Internal thoracic Brachial Ulnar collateral arteries Abdominal aorta Ulnar recurrent arteries Arteries of the chest and upper limb, a diagrammatic view © 2012 Pearson Education, Inc. Figure 21-22b Arteries of the Chest and Upper Limb Right common carotid Right vertebral Spinal cord, cervical vertebrae (right side); fuses with left vertebral, forming basilar artery after entering cranium via foramen magnum Left common carotid Left vertebral Right thyrocervical trunk Muscles, skin, tissues of neck, thyroid gland, shoulders, and upper back (right side) Right axillary Muscles of the right pectoral region and axilla Brachiocephalic trunk Right subclavian Right internal thoracic Skin and muscles of chest and abdomen, mammary gland (right side), pericardium Right brachial To structures of the arm Left internal thoracic THORACIC AORTA (see Fig. 21−25) Forearm, ulnar side Connected by anastomoses of palmar arches that supply digital arteries AORTIC ARCH ASCENDING AORTA Right radial Right ulnar Forearm, radial side Left subclavian LEFT VENTRICLE ABDOMINAL AORTA (see Fig. 21−26) A flowchart of the arteries of the chest and upper limb © 2012 Pearson Education, Inc. Left thyrocervical trunk Left axillary Left brachial Left ulnar Left radial 21-7 The Systemic Circuit • Branches of the Aortic Arch • Deliver blood to head, neck, shoulders, and upper limbs 1. Brachiocephalic trunk 2. Left common carotid artery 3. Left subclavian artery © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The Subclavian Arteries • Leaving the thoracic cavity: • Become axillary artery in arm • And brachial artery distally © 2012 Pearson Education, Inc. Figure 21-22a Arteries of the Chest and Upper Limb Suprascapular Thyrocervical trunk Right subclavian Thoracoacromial Axillary Right common carotid Left common carotid Vertebral Brachiocephalic trunk Left subclavian Lateral thoracic Anterior humeral circumflex Aortic arch Ascending aorta Thoracic aorta Posterior humeral circumflex Subscapular Heart Deep brachial Intercostal arteries Internal thoracic Brachial Ulnar collateral arteries Abdominal aorta Ulnar recurrent arteries Arteries of the chest and upper limb, a diagrammatic view © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The Brachial Artery • Divides at coronoid fossa of humerus • Into radial artery and ulnar artery • Fuse at wrist to form: • Superficial and deep palmar arches • Which supply digital arteries © 2012 Pearson Education, Inc. Figure 21-22a Arteries of the Chest and Upper Limb Radial Anterior crural interosseous Ulnar Deep palmar arch Superficial palmar arch Digital arteries © 2012 Pearson Education, Inc. Arteries of the chest and upper limb, a diagrammatic view 21-7 The Systemic Circuit • The Common Carotid Arteries • Each common carotid divides into: • External carotid artery - supplies blood to structures of the neck, lower jaw, and face • Internal carotid artery - enters skull and delivers blood to brain • Divides into three branches 1. Ophthalmic artery 2. Anterior cerebral artery 3. Middle cerebral artery © 2012 Pearson Education, Inc. Figure 21-23 Arteries of the Neck and Head Anterior cerebral Middle cerebral Ophthalmic Cerebral arterial circle Carotid canal Posterior cerebral Basilar Internal carotid Carotid sinus Vertebral Inferior thyroid Thyrocervical trunk Transverse cervical Suprascapular Subclavian Axillary Internal thoracic Second rib © 2012 Pearson Education, Inc. Clav ic Firs t r ib le Figure 21-23 Arteries of the Neck and Head Branches of the External Carotid Superficial temporal Maxillary Occipital Facial Lingual External carotid Common carotid Clav i Firs t © 2012 Pearson Education, Inc. rib c le Brachiocephalic trunk 21-7 The Systemic Circuit • The Vertebral Arteries • Also supply brain with blood • Left and right vertebral arteries • Arise from subclavian arteries • Enter cranium through foramen magnum • Fuse to form basilar artery • Branches to form posterior cerebral arteries • Posterior cerebral arteries • Become posterior communicating arteries © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Anastomoses • The cerebral arterial circle (or circle of Willis) interconnects: • The internal carotid arteries • And the basilar artery © 2012 Pearson Education, Inc. Figure 21-24a Arteries of the Brain Cerebral Arterial Circle Anterior cerebral Anterior communicating Anterior cerebral Ophthalmic Internal carotid (cut) Posterior communicating Posterior cerebral Middle cerebral Pituitary gland Posterior cerebral Basilar Vertebral Cerebellar Inferior surface © 2012 Pearson Education, Inc. Figure 21-24b Arteries of the Brain Middle cerebral Posterior cerebral Basilar Vertebral Ophthalmic Cerebral arterial circle Internal carotid Lateral view © 2012 Pearson Education, Inc. Anterior cerebral 21-7 The Systemic Circuit • The Descending Aorta • Thoracic aorta • Supplies organs of the chest • Bronchial arteries • Pericardial arteries • Esophageal arteries • Mediastinal arteries • Supplies chest wall • Intercostal arteries • Superior phrenic arteries © 2012 Pearson Education, Inc. Figure 21-25a Major Arteries of the Trunk Aortic arch Internal thoracic Thoracic aorta Somatic Branches of the Thoracic Aorta Intercostal arteries Superior phrenic Inferior phrenic A diagrammatic view, with most of the thoracic and abdominal organs removed © 2012 Pearson Education, Inc. Figure 21-25a Major Arteries of the Trunk Visceral Branches of the Thoracic Aorta Bronchial arteries Esophageal arteries Mediastinal arteries Pericardial arteries A diagrammatic view, with most of the thoracic and abdominal organs removed © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The Descending Aorta • Abdominal Aorta • Divides at terminal segment of the aorta into: • Left common iliac artery • Right common iliac artery • Unpaired branches • Major branches to visceral organs • Paired branches • To body wall • Kidneys • Urinary bladder • Structures outside abdominopelvic cavity © 2012 Pearson Education, Inc. Figure 21-25a Major Arteries of the Trunk Diaphragm Adrenal Renal Gonadal Lumbar Terminal segment of the aorta Common iliac Median sacral A diagrammatic view, with most of the thoracic and abdominal organs removed © 2012 Pearson Education, Inc. Figure 21-25a Major Arteries of the Trunk Celiac Trunk Left gastric Splenic Common hepatic Superior mesenteric Abdominal aorta Inferior mesenteric A diagrammatic view, with most of the thoracic and abdominal organs removed © 2012 Pearson Education, Inc. Figure 21-26 Arteries Supplying the Abdominopelvic Organs Branches of the Common Hepatic Artery Hepatic artery proper (liver) Gastroduodenal (stomach and duodenum) Cystic (gallbladder) Liver Right gastric (stomach) Right gastroepiploid (stomach and duodenum) Superior pancreaticoduodenal (duodenum) Ascending colon Pancreas Superior Mesenteric Artery Inferior pancreaticoduodenal (pancreas and duodenum) Middle colic (cut) (large intestine) Right colic (large intestine) Ileocolic (large intestine) Small intestine Intestinal arteries (small intestine) Rectum © 2012 Pearson Education, Inc. Figure 21-26 Arteries Supplying the Abdominopelvic Organs The Celiac Trunk Common hepatic Left gastric Splenic Spleen Stomach Pancreas Branches of the Splenic Artery Left gastroepiploic (stomach) Pancreatic (pancreas) Inferior Mesenteric Artery Left colic (colon) Sigmoid (colon) Rectal (rectum) Small intestine Sigmoid colon Rectum © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Arteries of the Pelvis and Lower Limbs • Femoral artery • Deep femoral artery • Becomes popliteal artery • Posterior to knee • Branches to form: • Posterior and anterior tibial arteries • Posterior gives rise to fibular artery © 2012 Pearson Education, Inc. Figure 21-25b Major Arteries of the Trunk Right common iliac Right external iliac Pelvis and right lower limb Pelvic muscles, skin, Left common iliac Right viscera of pelvis (urinary and reproductive organs), internal perineum, gluteal region, iliac and medial thigh Superior gluteal Hip muscles, hip joint Obturator Ilium, hip and thigh muscles, hip joint and femoral head Left internal iliac Lateral rotators of Internal hip; rectum, anus, muscles, pudendalperineal external genitalia Lateral sacral Skin and muscles of sacrum A flowchart showing major arteries of the trunk © 2012 Pearson Education, Inc. Pelvis and left lower limb Left external iliac Figure 21-27a Arteries of the Lower Limb Common iliac External iliac Superior gluteal Inguinal ligament Internal iliac Lateral sacral Internal pudendal Obturator Deep femoral Medial femoral circumflex Lateral femoral circumflex Femoral Descending genicular © 2012 Pearson Education, Inc. Anterior view Figure 21-27a Arteries of the Lower Limb Popliteal Anterior tibial Posterior tibial Fibular Dorsalis pedis Medial plantar Lateral plantar Dorsal arch Plantar arch © 2012 Pearson Education, Inc. Anterior view Figure 21-27b Arteries of the Lower Limb Superior gluteal Internal pudendal Obturator Deep femoral Medial femoral circumflex Femoral Descending genicular © 2012 Pearson Education, Inc. Right external iliac Posterior view Lateral femoral circumflex Figure 21-27b Arteries of the Lower Limb Popliteal Anterior tibial Posterior tibial Fibular © 2012 Pearson Education, Inc. Posterior view Figure 21-27c Arteries of the Lower Limb EXTERNAL ILIAC Femoral Thigh Descending genicular Deep femoral Skin of leg, knee joint Hip joint, femoral head, deep muscles of the thigh Medial femoral circumflex Adductor muscles, obturator muscles, hip joint Fibular Lateral femoral circumflex Quadriceps muscles Posterior tibial Popliteal Leg and foot Anterior tibial Connected by anastomoses of dorsalis pedis, dorsal arch, and plantar arch, which supply distal portions of the foot and the toes © 2012 Pearson Education, Inc. A flowchart of blood flow to a lower limb 21-7 The Systemic Circuit • Systemic Veins • Complementary Arteries and Veins • Run side by side • Branching patterns of peripheral veins are more variable • In neck and limbs • One set of arteries (deep) • Two sets of veins (one deep, one superficial) • Venous system controls body temperature © 2012 Pearson Education, Inc. Figure 21-28 An Overview of the Major Systemic Veins KEY Superficial veins Deep veins Vertebral External jugular Subclavian Axillary Brachial Internal jugular Brachiocephalic Superior vena cava Intercostal veins Basilic Hepatic veins Median cubital Inferior vena cava Renal Gonadal Radial Lumbar veins Median antebrachial Left and right common iliac External iliac Internal iliac Ulnar Palmar venous arches Digital veins Deep femoral Femoral © 2012 Pearson Education, Inc. Figure 21-28 An Overview of the Major Systemic Veins Femoral Great saphenous Popliteal Small saphenous Posterior tibial Anterior tibial Fibular KEY Plantar venous arch Dorsal venous arch © 2012 Pearson Education, Inc. Superficial veins Deep veins 21-7 The Systemic Circuit • The Superior Vena Cava (SVC) • Receives blood from the tissues and organs of: • Head • Neck • Chest • Shoulders • Upper limbs © 2012 Pearson Education, Inc. Figure 21-29c Major Veins of the Head, Neck, and Brain Superior sagittal sinus Superficial cerebral veins Temporal Deep cerebral Cavernous sinus Maxillary Inferior sagittal sinus Great cerebral Straight sinus Petrosal sinuses Right transverse sinus Facial Occipital sinus Sigmoid sinus Occipital Vertebral External jugular Internal jugular Right subclavian Clavicle Right brachiocephalic Axillary Left brachiocephalic Firs t © 2012 Pearson Education, Inc. ri b Superior vena cava Internal thoracic Veins draining the brain and the superficial and deep portions of the head and neck. 21-7 The Systemic Circuit • The Dural Sinuses • Superficial cerebral veins and small veins of the brain stem • Empty into network of dural sinuses • Superior and inferior sagittal sinuses • Petrosal sinuses • Occipital sinus • Left and right transverse sinuses • Straight sinus © 2012 Pearson Education, Inc. Figure 21-29b Major Veins of the Head, Neck, and Brain Inferior sagittal Superior sagittal sinus sinus Great cerebral vein Straight sinus Occipital sinus Cavernous sinus Petrosal sinuses Internal jugular Vertebral vein Right transverse sinus Right sigmoid sinus © 2012 Pearson Education, Inc. A lateral view of the brain showing the venous distribution. 21-7 The Systemic Circuit • Cerebral Veins • Great cerebral vein • Drains to straight sinus • Other cerebral veins • Drain to cavernous sinus • Which drains to petrosal sinus • Vertebral Veins • Empty into brachiocephalic veins of chest © 2012 Pearson Education, Inc. Figure 21-29a Major Veins of the Head, Neck, and Brain Superior sagittal, sinus (cut) Cavernous sinus Cerebral veins Petrosal sinus Internal jugular Sigmoid sinus Cerebellar veins Transverse sinus Straight sinus Occipital sinus An inferior view of the brain, showing the venous distribution. © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Superficial Veins of the Head and Neck • Converge to form: • Temporal, facial, and maxillary veins • Temporal and maxillary veins • Drain to external jugular vein • Facial vein • Drains to internal jugular vein © 2012 Pearson Education, Inc. Figure 21-29c Major Veins of the Head, Neck, and Brain Superior sagittal sinus Superficial cerebral veins Temporal Deep cerebral Cavernous sinus Maxillary Inferior sagittal sinus Great cerebral Straight sinus Petrosal sinuses Right transverse sinus Facial Occipital sinus Sigmoid sinus Occipital Vertebral External jugular Internal jugular Right subclavian Clavicle Right brachiocephalic Axillary Left brachiocephalic Firs t © 2012 Pearson Education, Inc. ri b Superior vena cava Internal thoracic Veins draining the brain and the superficial and deep portions of the head and neck. 21-7 The Systemic Circuit • Veins of the Hand • Digital veins • Empty into superficial and deep palmar veins • Which interconnect to form palmar venous arches © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Veins of the Hand • Superficial arch empties into: • Cephalic vein • Median antebrachial vein • Basilic vein • Median cubital vein • Deep palmar veins drain into: • Radial and ulnar veins • Which fuse above elbow to form brachial vein © 2012 Pearson Education, Inc. Figure 21-30 The Venous Drainage of the Abdomen and Chest Median cubital Cephalic Anterior crural interosseous Basilic Ulnar Palmar venous arches Digital veins KEY Superficial veins Deep veins © 2012 Pearson Education, Inc. Radial Median antebrachial 21-7 The Systemic Circuit • The Brachial Vein • Merges with basilic vein • To become axillary vein • Cephalic vein joins axillary vein • To form subclavian vein • Merges with external and internal jugular veins • To form brachiocephalic vein • Which enters thoracic cavity © 2012 Pearson Education, Inc. Figure 21-30 The Venous Drainage of the Abdomen and Chest Vertebral Internal jugular External jugular Subclavian Highest intercostal Brachiocephalic Axillary Cephalic Accessory hemiazygos Hemiazygos Brachial Intercostal veins INFERIOR VENA CAVA Basilic Phrenic veins Adrenal veins KEY Superficial veins Deep veins © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Veins of the Thoracic Cavity • Brachiocephalic vein receives blood from: • Vertebral vein • Internal thoracic vein • The Left and Right Brachiocephalic Veins • Merge to form the superior vena cava (SVC) © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Tributaries of the Superior Vena Cava • Azygos vein and hemiazygos vein, which receive blood from: 1. Intercostal veins 2. Esophageal veins 3. Veins of other mediastinal structures © 2012 Pearson Education, Inc. Figure 21-30 The Venous Drainage of the Abdomen and Chest SUPERIOR VENA CAVA Mediastinal veins Esophageal veins Azygos Internal thoracic Hepatic veins Renal veins Gonadal veins Lumbar veins Common iliac KEY Superficial veins Deep veins © 2012 Pearson Education, Inc. Internal iliac External iliac Medial sacral Figure 21-31a Flowcharts of Circulation to the Superior and Inferior Venae Cavae Left vertebral Right vertebral Right external jugular Right subclavian Right internal jugular Right brachiocephalic Left internal jugular Left and right internal thoracic veins Collects blood from cranium, face, and neck Collect blood from structures of anterior thoracic wall Right axillary Veins of the right upper limb Right intercostal veins Mediastinal veins Collect blood from the mediastinum SUPERIOR VENA CAVA Left brachiocephalic Through highest intercostal vein RIGHT ATRIUM Collect blood from vertebrae and body wall Azygos KEY Superficial veins Deep veins Esophageal veins Hemiazygos Collect blood from the eophagus Tributaries of the superior vena cava © 2012 Pearson Education, Inc. Collects blood from cranium, spinal cord, vertebrae Left intercostal veins Collect blood from vertebrae and body wall Figure 21-31a Flowcharts of Circulation to the Superior and Inferior Venae Cavae Left external jugular Left brachiocephalic Collects blood from neck, face, salivary glands, scalp Left subclavian Left axillary Left cephalic Collects blood from lateral surface of upper limb KEY Superficial veins Deep veins Left brachial Collects blood from forearm, wrist, and hand Left basilic Collects blood from medial surface of upper limb Interconnected by median cubital vein and median antebrachial network Left radial Radial side of forearm Left ulnar Ulnar side of forearm Venous network of wrist and hand Tributaries of the superior vena cava © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The Inferior Vena Cava (IVC) • Collects blood from organs inferior to the diaphragm © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Veins of the Foot • Capillaries of the sole • Drain into a network of plantar veins • Which supply the plantar venous arch • Drain into deep veins of leg: • Anterior tibial vein • Posterior tibial vein • Fibular vein • All three join to become popliteal vein © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The Dorsal Venous Arch • Collects blood from: • Superior surface of foot • Digital veins • Drains into two superficial veins 1. Great saphenous vein (drains into femoral vein) 2. Small saphenous vein (drains into popliteal vein) © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The Popliteal Vein • Becomes the femoral vein • Before entering abdominal wall, receives blood from: • Great saphenous vein • Deep femoral vein • Femoral circumflex vein • Inside the pelvic cavity • Becomes the external iliac vein © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The External Iliac Veins • Are joined by internal iliac veins • To form right and left common iliac veins • The right and left common iliac veins • Merge to form the inferior vena cava © 2012 Pearson Education, Inc. Figure 21-32a Venous Drainage from the Lower Limb External iliac Common iliac Internal iliac Gluteal Internal pudendal Lateral sacral Obturator Femoral Femoral circumflex Deep femoral Femoral Great saphenous Popliteal Small saphenous Anterior tibial Posterior tibial Fibular Dorsal venous arch Plantar venous arch Digital © 2012 Pearson Education, Inc. An anterior view Figure 21-32b Venous Drainage from the Lower Limb External iliac Gluteal Internal pudendal Obturator Femoral Femoral circumflex Deep femoral Femoral Great saphenous Popliteal Small saphenous Anterior tibial Posterior tibial Fibular © 2012 Pearson Education, Inc. A posterior view Figure 21-32c Venous Drainage from the Lower Limb EXTERNAL ILIAC Deep femoral Small saphenous Collects blood from the thigh Femoral Collects blood from superficial veins of the leg and foot Collects blood from the superficial veins of the lower limb KEY Popliteal Fibular Great saphenous Posterior tibial Superficial veins Deep veins Anterior tibial Extensive anastomoses interconnect veins of the ankle and foot A flowchart of venous circulation from a lower limb © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Major Tributaries of the Abdominal Inferior Vena Cava 1. Lumbar veins 2. Gonadal veins 3. Hepatic veins 4. Renal veins 5. Adrenal veins 6. Phrenic veins © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • The Hepatic Portal System • Connects two capillary beds • Delivers nutrient-laden blood • From capillaries of digestive organs • To liver sinusoids for processing © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit Tributaries of the Hepatic Portal Vein 1. Inferior mesenteric vein • Drains part of large intestine 1. Splenic vein • Drains spleen, part of stomach, and pancreas 3. Superior mesenteric vein • Drains part of stomach, small intestine, and part of large intestine 4. Left and right gastric veins • Drain part of stomach 4. Cystic vein • Drains gallbladder © 2012 Pearson Education, Inc. 21-7 The Systemic Circuit • Blood Processed in Liver • After processing in liver sinusoids (exchange vessels): • Blood collects in hepatic veins and empties into inferior vena cava © 2012 Pearson Education, Inc. Figure 21-33 The Hepatic Portal System Inferior vena cava Hepatic Liver Cystic Hepatic portal Superior Mesenteric Vein and Its Tributaries Pancreaticoduodenal Middle colic (from transverse colon) Right colic (ascending colon) Ileocolic (Ileum and ascending colon) Intestinal (small intestine) © 2012 Pearson Education, Inc. Pancreas Figure 21-33 The Hepatic Portal System Left gastric Right gastric Splenic Vein and Its Tributaries Stomach Spleen Pancreas Left gastroepiploic (stomach) Right gastroepiploic (stomach) Pancreatic Descending colon Inferior Mesenteric Vein and Its Tributaries Left colic (descending colon) Sigmoid (sigmoid colon) Superior rectal (rectum) © 2012 Pearson Education, Inc. Figure 21-31b Flowcharts of Circulation to the Superior and Inferior Venae Cavae KEY RIGHT ATRIUM Superficial veins Deep veins INFERIOR VENA CAVA Hepatic veins Collect blood from the liver Gonadal veins Collect blood from the gonads (testes or ovaries) Lumbar veins Collect blood from the spinal cord and body wall Right common iliac Right external iliac Blood from veins in right lower limb Right internal iliac Phrenic veins Collect blood from the diaphragm Adrenal veins Collect blood from the adrenal glands Renal veins Collect blood from the kidneys Left common iliac Left internal iliac Collect blood from the pelvic muscles, skin, urinary and reproductive organs of pelvic cavity Left external iliac Blood from veins in left lower limb Superior Internal Obturator Lateral sacral gluteal pudendal veins veins veins veins © 2012 Pearson Education, Inc. Tributaries of the inferior vena cava 21-8 Fetal and Maternal Circulation • Fetal and Maternal Cardiovascular Systems Promote the Exchange of Materials • Embryonic lungs and digestive tract nonfunctional • Respiratory functions and nutrition provided by placenta © 2012 Pearson Education, Inc. 21-8 Fetal and Maternal Circulation • Placental Blood Supply • Blood flows to the placenta • Through a pair of umbilical arteries that arise from internal iliac arteries • Enters umbilical cord • Blood returns from placenta • In a single umbilical vein that drains into ductus venosus • Ductus venosus • Empties into inferior vena cava © 2012 Pearson Education, Inc. 21-8 Fetal and Maternal Circulation • Before Birth • Fetal lungs are collapsed • O2 provided by placental circulation © 2012 Pearson Education, Inc. 21-8 Fetal and Maternal Circulation • Fetal Pulmonary Circulation Bypasses • Foramen ovale • Interatrial opening • Covered by valve-like flap • Directs blood from right to left atrium • Ductus arteriosus • Short vessel • Connects pulmonary and aortic trunks © 2012 Pearson Education, Inc. 21-8 Fetal and Maternal Circulation • Cardiovascular Changes at Birth • Newborn breathes air • Lungs expand • Pulmonary vessels expand • Reduced resistance allows blood flow • Rising O2 causes ductus arteriosus constriction • Rising left atrium pressure closes foramen ovale • Pulmonary circulation provides O2 © 2012 Pearson Education, Inc. Figure 21-34a Fetal Circulation Aorta Foramen ovale (open) Ductus arteriosus (open) Pulmonary trunk Umbilical vein Liver Placenta Umbilical cord Umbilical arteries Blood flow to and from the placenta in full-term fetus (before birth) © 2012 Pearson Education, Inc. Inferior vena cava Ductus venosus Figure 21-34b Fetal Circulation Ductus arteriosus (closed) Pulmonary trunk Left atrium Foramen ovale (closed) Right atrium Left ventricle Inferior vena cava Right ventricle Blood flow through the neonatal (newborn) heart after delivery © 2012 Pearson Education, Inc. Figure 21-35 Congenital Heart Problems Normal Heart Structure Most heart problems reflect deviations from the normal formation of the heart and its connections to the great vessels. © 2012 Pearson Education, Inc. 21-8 Fetal and Maternal Circulation • Patent Foramen Ovale and Patent Ductus Arteriosus • In patent (open) foramen ovale blood recirculates through pulmonary circuit instead of entering left ventricle • The movement, driven by relatively high systemic pressure, is a “left-to-right shunt” • Arterial oxygen content is normal, but left ventricle must work much harder than usual to provide adequate blood flow through systemic circuit © 2012 Pearson Education, Inc. 21-8 Fetal and Maternal Circulation • Patent Foramen Ovale and Patent Ductus Arteriosus • Pressures rise in the pulmonary circuit • If pulmonary pressures rise enough, they may force blood into systemic circuit through ductus arteriosus • A patent ductus arteriosus creates a “right-to-left shunt” • Because circulating blood is not adequately oxygenated, it develops deep red color • Skin develops blue tones typical of cyanosis and infant is known as a “blue baby” © 2012 Pearson Education, Inc. Figure 21-35 Congenital Heart Problems Patent ductus arteriosus Patent foramen ovale Patent Foramen Ovale and Patent Ductus Arteriosus If the foramen ovale remains open, or patent, blood recirculates through the pulmonary circuit instead of entering the left ventricle. The movement, driven by the relatively high systemic pressure, is called a “left-to-right shunt.” Arterial oxygen content is normal, but the left ventricle must work much harder than usual to provide adequate blood flow through © 2012 Pearson Education, Inc. the systemic circuit. Hence, pressures rise in the pulmonary circuit. If the pulmonary pressures rise enough, they may force blood into the systemic circuit through the ductus arteriosus. This condition—a patent ductus arteriosus— creates a “right-to-left shunt.” Because the circulating blood is not adequately oxygenated, it develops a deep red color. The skin then develops the blue tones typical of cyanosis and the infant is known as a “blue baby.” 21-8 Fetal and Maternal Circulation • Tetralogy of Fallot • Complex group of heart and circulatory defects that affect 0.10 percent of newborn infants 1. Pulmonary trunk is abnormally narrow (pulmonary stenosis) 2. Interventricular septum is incomplete 3. Aorta originates where interventricular septum normally ends 4. Right ventricle is enlarged and both ventricles thicken in response to increased workload © 2012 Pearson Education, Inc. Figure 21-35 Congenital Heart Problems Patent ductus arteriosus Pulmonary stenosis Ventricular septal defect Enlarged right ventricle Tetralogy of Fallot © 2012 Pearson Education, Inc. The tetralogy of Fallot (fa-LO)¯is a complex ventricle is enlarged and both ventricles group of heart and circulatory defects that thicken in response to the increased workload. affect 0.10 percent of newborn infants. In this condition, (1) the pulmonary trunk is abnormally narrow (pulmonary stenosis), (2) the interventricular septum is incomplete, (3) the aorta originates where the interventricular septum normally ends, and (4) the right 21-8 Fetal and Maternal Circulation • Ventricular Septal Defect • Openings in interventricular septum that separate right and left ventricles • The most common congenital heart problems, affecting 0.12 percent of newborns • Opening between the two ventricles has an effect similar to a connection between the atria • When more powerful left ventricle beats, it ejects blood into right ventricle and pulmonary circuit © 2012 Pearson Education, Inc. Figure 21-35 Congenital Heart Problems Ventricular Septal Defect Ventricular septal defect Ventricular septum © 2012 Pearson Education, Inc. Ventricular septal defects are openings in the interventricular septum that separate the right and left ventricles. These defects are the most common congenital heart problems, affecting 0.12 percent of newborns. The opening between the two ventricles has an effect similar to a connection between the atria: When the more powerful left ventricle beats, it ejects blood into the right ventricle and pulmonary circuit. 21-8 Fetal and Maternal Circulation • Atrioventricular Septal Defect • Both the atria and ventricles are incompletely separated • Results are quite variable, depending on extent of defect and effects on atrioventricular valves • This type of defect most commonly affects infants with Down’s syndrome, a disorder caused by the presence of an extra copy of chromosome 21 © 2012 Pearson Education, Inc. Figure 21-35 Congenital Heart Problems Atrioventricular Septal Defect Atrial defect Ventricular defect © 2012 Pearson Education, Inc. In an atriovenricular septal defect, both the atria and ventricles are incompletely separated. The results are quite variable, depending on the extent of the defect and the effects on the atrioventricular valves. This type of defect most commonly affects infants with Down’s syndrome, a disorder caused by the presence of an extra copy of chromosome 21. 21-8 Fetal and Maternal Circulation • Transposition of Great Vessels • The aorta is connected to right ventricle instead of to left ventricle • The pulmonary artery is connected to left ventricle instead of right ventricle • This malformation affects 0.05 percent of newborn infants © 2012 Pearson Education, Inc. Figure 21-35 Congenital Heart Problems Transposition of the Great Vessels Patent ductus arteriosus Aorta Pulmonary trunk © 2012 Pearson Education, Inc. In the transposition of great vessels, the aorta is connected to the right ventricle instead of to the left ventricle, and the pulmonary artery is connected to the left ventricle instead of the right ventricle. This malformation affects 0.05 percent of newborn infants. 21-9 Effects of Aging and the Cardiovascular System • Cardiovascular Capabilities Decline with Age • Age-related changes occur in: • Blood • Heart • Blood vessels © 2012 Pearson Education, Inc. 21-9 Effects of Aging and the Cardiovascular System • Three Age-Related Changes in Blood 1. Decreased hematocrit 2. Peripheral blockage by blood clot (thrombus) 3. Pooling of blood in legs • Due to venous valve deterioration © 2012 Pearson Education, Inc. 21-9 Effects of Aging and the Cardiovascular System • Five Age-Related Changes in the Heart 1. Reduced maximum cardiac output 2. Changes in nodal and conducting cells 3. Reduced elasticity of cardiac (fibrous) skeleton 4. Progressive atherosclerosis 5. Replacement of damaged cardiac muscle cells by scar tissue © 2012 Pearson Education, Inc. 21-9 Effects of Aging and the Cardiovascular System • Three Age-Related Changes in Blood Vessels 1. Arteries become less elastic • Pressure change can cause aneurysm 1. Calcium deposits on vessel walls • Can cause stroke or infarction 1. Thrombi can form • At atherosclerotic plaques © 2012 Pearson Education, Inc. 21-9 Cardiovascular System Integration • Many Categories of Cardiovascular Disorders • Disorders may: • Affect all cells and systems • Be structural or functional • Result from disease or trauma © 2012 Pearson Education, Inc. Figure 21-36 System Integrator: The Cardiovascular System INTEGRATOR Controls patterns of circulation in peripheral tissues; modifies heart rate and regulates blood pressure; releases ADH Erythropoietin regulates production of RBCs; several hormones elevate blood pressure; epinephrine stimulates cardiac muscle, elevating heart rate and contractile force Endothelial cells maintain blood—brain barrier; helps generate CSF Distributes hormones throughout the body; heart secretes ANP and BNP Skeletal Page 275 Skeletal muscle contractions assist in moving blood through veins; protects superficial blood vessels, especially in neck and limbs Muscular Page 369 Skeletal Delivers oxygen and nutrients, removes carbon dioxide, lactic acid, and heat during skeletal muscle activity Muscular Transports calcium and phosphate for bone deposition; delivers EPO to red bone marrow, parathyroid hormone, and calcitonin to osteoblasts and osteoclasts Provides calcium needed for normal cardiac muscle contraction; protects blood cells developing in red bone marrow Nervous Delivers immune system cells to injury sites; clotting response seals breaks in skin surface; carries away toxins from sites of infection; provides heat Integumentary Page 165 Body System Nervous Page 543 Cardiovascular System Stimulation of mast cells produces localized changes in blood flow and capillary permeability Endocrine Integumentary Cardiovascular System Endocrine Page 632 SYSTEM Body System Respiratory Page 857 Digestive Page 910 Reproductive Page 1072 The most extensive communication occurs between the cardiovascular and lymphatic systems. Not only are the two systems physically interconnected, but cells of the lymphatic system also move from one part of the body to another within the vessels of the cardiovascular system. We examine the lymphatic system in detail, including its role in the immune response, in the next chapter. Urinary Page 992 The section on vessel distribution demonstrated the extent of the anatomical connections between the cardiovascular system and other organ systems. This figure summarizes some of the physiological relationships involved. Lymphatic Page 807 The CARDIOVASCULAR System © 2012 Pearson Education, Inc.
