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PowerPoint® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community Ninth Edition College Human Anatomy & Physiology CHAPTER 19 The Cardiovascular System: Blood Vessels © Annie Leibovitz/Contact Press Images © 2013 Pearson Education, Inc. Blood Vessels • Delivery system of dynamic structures that begins and ends at heart – Arteries: carry blood away from heart; oxygenated except for pulmonary circulation and umbilical vessels of fetus – Capillaries: contact tissue cells; directly serve cellular needs – Veins: carry blood toward heart © 2013 Pearson Education, Inc. Figure 19.1a Generalized structure of arteries, veins, and capillaries. Artery Vein © 2013 Pearson Education, Inc. Structure of Blood Vessel Walls • Lumen – Central blood-containing space • Three wall layers in arteries and veins – Tunica intima, tunica media, and tunica externa • Capillaries – Endothelium with sparse basal lamina © 2013 Pearson Education, Inc. Figure 19.1b Generalized structure of arteries, veins, and capillaries. Tunica intima • Endothelium • Subendothelial layer • Internal elastic membrane Tunica media (smooth muscle and elastic fibers) • External elastic membrane Valve Tunica externa (collagen fibers) • Vasa vasorum Lumen Lumen Artery Capillary network Vein Basement membrane Endothelial cells Capillary © 2013 Pearson Education, Inc. Tunics • Tunica intima – Endothelium lines lumen of all vessels • Continuous with endocardium • Slick surface reduces friction – Subendothelial layer in vessels larger than 1 mm; connective tissue basement membrane © 2013 Pearson Education, Inc. Tunics • Tunica media – Smooth muscle and sheets of elastin – Sympathetic vasomotor nerve fibers control vasoconstriction and vasodilation of vessels • Influence blood flow and blood pressure © 2013 Pearson Education, Inc. Tunics • Tunica externa (tunica adventitia) – Collagen fibers protect and reinforce; anchor to surrounding structures – Contains nerve fibers, lymphatic vessels – Vasa vasorum of larger vessels nourishes external layer © 2013 Pearson Education, Inc. Blood Vessels • Vessels vary in length, diameter, wall thickness, tissue makeup • See figure 19.2 for interaction with lymphatic vessels © 2013 Pearson Education, Inc. Figure 19.2 The relationship of blood vessels to each other and to lymphatic vessels. Venous system Large veins (capacitance vessels) Arterial system Heart Elastic arteries (conducting arteries) Large lymphatic vessels Lymph node Lymphatic system Small veins (capacitance vessels) Muscular arteries (distributing arteries) Arteriovenous anastomosis Lymphatic capillaries Sinusoid Arterioles (resistance vessels) Terminal arteriole Postcapillary venule © 2013 Pearson Education, Inc. Thoroughfare channel Capillaries (exchange vessels) Precapillary sphincter Metarteriole Arterial System: Elastic Arteries • Large thick-walled arteries with elastin in all three tunics • Aorta and its major branches • Large lumen offers low resistance • Inactive in vasoconstriction • Act as pressure reservoirs—expand and recoil as blood ejected from heart – Smooth pressure downstream © 2013 Pearson Education, Inc. Arterial System: Muscular Arteries • Distal to elastic arteries – Deliver blood to body organs • Thick tunica media with more smooth muscle • Active in vasoconstriction © 2013 Pearson Education, Inc. Arterial System: Arterioles • Smallest arteries • Lead to capillary beds • Control flow into capillary beds via vasodilation and vasoconstriction © 2013 Pearson Education, Inc. Table 19.1 Summary of Blood Vessel Anatomy (1 of 2) © 2013 Pearson Education, Inc. Capillaries • Microscopic blood vessels • Walls of thin tunica intima – In smallest one cell forms entire circumference • Pericytes help stabilize their walls and control permeability • Diameter allows only single RBC to pass at a time © 2013 Pearson Education, Inc. Capillaries • In all tissues except for cartilage, epithelia, cornea and lens of eye • Provide direct access to almost every cell • Functions – Exchange of gases, nutrients, wastes, hormones, etc., between blood and interstitial fluid © 2013 Pearson Education, Inc. Capillaries • Three structural types 1. Continuous capillaries 2. Fenestrated capillaries 3. Sinusoid capillaries (sinusoids) © 2013 Pearson Education, Inc. Continuous Capillaries • Abundant in skin and muscles – Tight junctions connect endothelial cells – Intercellular clefts allow passage of fluids and small solutes • Continuous capillaries of brain unique – Tight junctions complete, forming blood brain barrier © 2013 Pearson Education, Inc. Figure 19.3a Capillary structure. Pericyte Red blood cell in lumen Intercellular cleft Endothelial cell Basement membrane Tight junction Endothelial nucleus Pinocytotic vesicles Continuous capillary. Least permeable, and most common (e.g., skin, muscle). © 2013 Pearson Education, Inc. Fenestrated Capillaries • Some endothelial cells contain pores (fenestrations) • More permeable than continuous capillaries • Function in absorption or filtrate formation (small intestines, endocrine glands, and kidneys) © 2013 Pearson Education, Inc. Figure 19.3b Capillary structure. Pinocytotic vesicles Red blood cell in lumen Fenestrations (pores) Endothelial nucleus Basement membrane Tight junction Intercellular cleft Endothelial cell Fenestrated capillary. Large fenestrations (pores) increase permeability. Occurs in areas of active absorption or filtration (e.g., kidney, small intestine). © 2013 Pearson Education, Inc. Sinusoid Capillaries • Fewer tight junctions; usually fenestrated; larger intercellular clefts; large lumens • Blood flow sluggish – allows modification – Large molecules and blood cells pass between blood and surrounding tissues • Found only in the liver, bone marrow, spleen, adrenal medulla • Macrophages in lining to destroy bacteria © 2013 Pearson Education, Inc. Figure 19.3c Capillary structure. Endothelial cell Red blood cell in lumen Large intercellular cleft Tight junction Incomplete basement membrane Nucleus of endothelial cell Sinusoid capillary. Most permeable. Occurs in special locations (e.g., liver, bone marrow, spleen). © 2013 Pearson Education, Inc. Capillary Beds • Microcirculation – Interwoven networks of capillaries between arterioles and venules – Terminal arteriole metarteriole – Metarteriole continuous with thoroughfare channel (intermediate between capillary and venule) – Thoroughfare channel postcapillary venule that drains bed © 2013 Pearson Education, Inc. Capillary Beds: Two Types of Vessels • Vascular shunt (metarteriole— thoroughfare channel) – Directly connects terminal arteriole and postcapillary venule • True capillaries – 10 to 100 exchange vessels per capillary bed – Branch off metarteriole or terminal arteriole © 2013 Pearson Education, Inc. Blood Flow Through Capillary Beds • True capillaries normally branch from metarteriole and return to thoroughfare channel • Precapillary sphincters regulate blood flow into true capillaries – Blood may go into true capillaries or to shunt • Regulated by local chemical conditions and vasomotor nerves © 2013 Pearson Education, Inc. Figure 19.4 Anatomy of a capillary bed. Precapillary sphincters Vascular shunt Metarteriole Thoroughfare channel True capillaries Terminal arteriole Postcapillary venule Sphincters open—blood flows through true capillaries. Terminal arteriole Postcapillary venule Sphincters closed—blood flows through metarteriole – thoroughfare channel and bypasses true capillaries. © 2013 Pearson Education, Inc. Venous System: Venules • Formed when capillary beds unite – Smallest postcapillary venules – Very porous; allow fluids and WBCs into tissues – Consist of endothelium and a few pericytes • Larger venules have one or two layers of smooth muscle cells © 2013 Pearson Education, Inc. Veins • Formed when venules converge • Have thinner walls, larger lumens compared with corresponding arteries • Blood pressure lower than in arteries • Thin tunica media; thick tunica externa of collagen fibers and elastic networks • Called capacitance vessels (blood reservoirs); contain up to 65% of blood supply © 2013 Pearson Education, Inc. Figure 19.5 Relative proportion of blood volume throughout the cardiovascular system. Pulmonary blood vessels 12% Systemic arteries and arterioles 15% Heart 8% Capillaries 5% Systemic veins and venules 60% © 2013 Pearson Education, Inc. Veins • Adaptations ensure return of blood to heart despite low pressure – Large-diameter lumens offer little resistance – Venous valves prevent backflow of blood • Most abundant in veins of limbs – Venous sinuses: flattened veins with extremely thin walls (e.g., coronary sinus of the heart and dural sinuses of the brain) © 2013 Pearson Education, Inc. Table 19.1 Summary of Blood Vessel Anatomy (2 of 2) © 2013 Pearson Education, Inc. Figure 19.1a Generalized structure of arteries, veins, and capillaries. Artery Vein © 2013 Pearson Education, Inc. Vascular Anastomoses • Interconnections of blood vessels • Arterial anastomoses provide alternate pathways (collateral channels) to given body region – Common at joints, in abdominal organs, brain, and heart; none in retina, kidneys, spleen • Vascular shunts of capillaries are examples of arteriovenous anastomoses • Venous anastomoses are common © 2013 Pearson Education, Inc. Physiology of Circulation: Definition of Terms • Blood flow – Volume of blood flowing through vessel, organ, or entire circulation in given period • Measured as ml/min • Equivalent to cardiac output (CO) for entire vascular system • Relatively constant when at rest • Varies widely through individual organs, based on needs © 2013 Pearson Education, Inc. Physiology of Circulation: Definition of Terms • Blood pressure (BP) – Force per unit area exerted on wall of blood vessel by blood • Expressed in mm Hg • Measured as systemic arterial BP in large arteries near heart – Pressure gradient provides driving force that keeps blood moving from higher to lower pressure areas © 2013 Pearson Education, Inc. Physiology of Circulation: Definition of Terms • Resistance (peripheral resistance) – Opposition to flow – Measure of amount of friction blood encounters with vessel walls, generally in peripheral (systemic) circulation • Three important sources of resistance – Blood viscosity – Total blood vessel length – Blood vessel diameter © 2013 Pearson Education, Inc. Resistance • Factors that remain relatively constant: – Blood viscosity • The "stickiness" of blood due to formed elements and plasma proteins • Increased viscosity = increased resistance – Blood vessel length • Longer vessel = greater resistance encountered © 2013 Pearson Education, Inc. Resistance • Blood vessel diameter – Greatest influence on resistance • Frequent changes alter peripheral resistance • Varies inversely with fourth power of vessel radius – E.g., if radius is doubled, the resistance is 1/16 as much – E.g., Vasoconstriction increased resistance © 2013 Pearson Education, Inc. Resistance • Small-diameter arterioles major determinants of peripheral resistance • Abrupt changes in diameter or fatty plaques from atherosclerosis dramatically increase resistance – Disrupt laminar flow and cause turbulent flow • Irregular fluid motion increased resistance © 2013 Pearson Education, Inc. Relationship Between Blood Flow, Blood Pressure, and Resistance • Blood flow (F) directly proportional to blood pressure gradient ( P) – If P increases, blood flow speeds up • Blood flow inversely proportional to peripheral resistance (R) – If R increases, blood flow decreases: F = P/R • R more important in influencing local blood flow because easily changed by altering blood vessel diameter © 2013 Pearson Education, Inc. Systemic Blood Pressure • Pumping action of heart generates blood flow • Pressure results when flow is opposed by resistance • Systemic pressure – Highest in aorta – Declines throughout pathway – 0 mm Hg in right atrium • Steepest drop occurs in arterioles © 2013 Pearson Education, Inc. Figure 19.6 Blood pressure in various blood vessels of the systemic circulation. 120 Systolic pressure 100 Mean pressure 80 60 40 Diastolic pressure 20 0 © 2013 Pearson Education, Inc. Arterial Blood Pressure • Reflects two factors of arteries close to heart – Elasticity (compliance or distensibility) – Volume of blood forced into them at any time • Blood pressure near heart is pulsatile © 2013 Pearson Education, Inc. Arterial Blood Pressure • Systolic pressure: pressure exerted in aorta during ventricular contraction – Averages 120 mm Hg in normal adult • Diastolic pressure: lowest level of aortic pressure • Pulse pressure = difference between systolic and diastolic pressure – Throbbing of arteries (pulse) © 2013 Pearson Education, Inc. Arterial Blood Pressure • Mean arterial pressure (MAP): pressure that propels blood to tissues • MAP = diastolic pressure + 1/3 pulse pressure • Pulse pressure and MAP both decline with increasing distance from heart • Ex. BP = 120/80; MAP = 93 mm Hg © 2013 Pearson Education, Inc. Capillary Blood Pressure • Ranges from 17 to 35 mm Hg • Low capillary pressure is desirable – High BP would rupture fragile, thin-walled capillaries – Most very permeable, so low pressure forces filtrate into interstitial spaces © 2013 Pearson Education, Inc. Venous Blood Pressure • Changes little during cardiac cycle • Small pressure gradient; about 15 mm Hg • Low pressure due to cumulative effects of peripheral resistance – Energy of blood pressure lost as heat during each circuit © 2013 Pearson Education, Inc. Factors Aiding Venous Return 1. Muscular pump: contraction of skeletal muscles "milks" blood toward heart; valves prevent backflow 2. Respiratory pump: pressure changes during breathing move blood toward heart by squeezing abdominal veins as thoracic veins expand 3. Venoconstriction under sympathetic control pushes blood toward heart © 2013 Pearson Education, Inc. Figure 19.7 The muscular pump. Venous valve (open) Contracted skeletal muscle Venous valve (closed) Vein Direction of blood flow © 2013 Pearson Education, Inc. Maintaining Blood Pressure • Requires – Cooperation of heart, blood vessels, and kidneys – Supervision by brain • Main factors influencing blood pressure – Cardiac output (CO) – Peripheral resistance (PR) – Blood volume © 2013 Pearson Education, Inc. Maintaining Blood Pressure • F = P/R; CO = P/R; P = CO × R • Blood pressure = CO × PR (and CO depends on blood volume) • Blood pressure varies directly with CO, PR, and blood volume • Changes in one variable quickly compensated for by changes in other variables © 2013 Pearson Education, Inc. Cardiac Output (CO) • CO = SV × HR; normal = 5.0-5.5 L/min • Determined by venous return, and neural and hormonal controls • Resting heart rate maintained by cardioinhibitory center via parasympathetic vagus nerves • Stroke volume controlled by venous return (EDV) © 2013 Pearson Education, Inc. Cardiac Output (CO) • During stress, cardioacceleratory center increases heart rate and stroke volume via sympathetic stimulation – ESV decreases and MAP increases © 2013 Pearson Education, Inc. Figure 19.8 Major factors enhancing cardiac output. Exercise BP activates cardiac centers in medulla Activity of respiratory pump (ventral body cavity pressure) Sympathetic activity Parasympathetic activity Activity of muscular pump (skeletal muscles) Epinephrine in blood Sympathetic venoconstriction Venous return Contractility of cardiac muscle ESV EDV Stroke volume (SV) Heart rate (HR) Initial stimulus Physiological response Result © 2013 Pearson Education, Inc. Cardiac output (CO = SV x HR) Control of Blood Pressure • Short-term neural and hormonal controls – Counteract fluctuations in blood pressure by altering peripheral resistance and CO • Long-term renal regulation – Counteracts fluctuations in blood pressure by altering blood volume © 2013 Pearson Education, Inc. Short-term Mechanisms: Neural Controls • Neural controls of peripheral resistance – Maintain MAP by altering blood vessel diameter • If low blood volume all vessels constricted except those to heart and brain – Alter blood distribution to organs in response to specific demands © 2013 Pearson Education, Inc. Short-term Mechanisms: Neural Controls • Neural controls operate via reflex arcs that involve – Baroreceptors – Cardiovascular center of medulla – Vasomotor fibers to heart and vascular smooth muscle – Sometimes input from chemoreceptors and higher brain centers © 2013 Pearson Education, Inc. The Cardiovascular Center • Clusters of sympathetic neurons in medulla oversee changes in CO and blood vessel diameter • Consists of cardiac centers and vasomotor center • Vasomotor center sends steady impulses via sympathetic efferents to blood vessels moderate constriction called vasomotor tone • Receives inputs from baroreceptors, chemoreceptors, and higher brain centers © 2013 Pearson Education, Inc. Short-term Mechanisms: Baroreceptor Reflexes • Baroreceptors located in – Carotid sinuses – Aortic arch – Walls of large arteries of neck and thorax © 2013 Pearson Education, Inc. Short-term Mechanisms: Baroreceptor Reflexes • Increased blood pressure stimulates baroreceptors to increase input to vasomotor center – Inhibits vasomotor and cardioacceleratory centers, causing arteriolar dilation and venodilation – Stimulates cardioinhibitory center – decreased blood pressure © 2013 Pearson Education, Inc. Short-term Mechanisms: Baroreceptor Reflexes • Decrease in blood pressure due to – Arteriolar vasodilation – Venodilation – Decreased cardiac output © 2013 Pearson Education, Inc. Short-term Mechanisms: Baroreceptor Reflexes • If MAP low – Reflex vasoconstriction increased CO increased blood pressure – Ex. Upon standing baroreceptors of carotid sinus reflex protect blood to brain; in systemic circuit as whole aortic reflex maintains blood pressure • Baroreceptors ineffective if altered blood pressure sustained © 2013 Pearson Education, Inc. Figure 19.9 Baroreceptor reflexes that help maintain blood pressure homeostasis. 3 Impulses from baroreceptors stimulate cardioinhibitory center (and inhibit cardioacceleratory center) and inhibit vasomotor center. 4a Sympathetic impulses to heart cause HR, contractility, and CO. 2 Baroreceptors in carotid sinuses and aortic arch are stimulated. 4b Rate of vasomotor impulses allows vasodilation, causing R. 1 Stimulus: Blood pressure (arterial blood pressure rises above normal range). 5 CO and R return blood pressure to homeostatic range. 1 Stimulus: 5 CO and R return blood pressure to homeostatic range. Blood pressure (arterial blood pressure falls below normal range). 4b Vasomotor fibers stimulate vasoconstriction, causing R. 2 Baroreceptors in carotid sinuses and aortic arch are inhibited. 4a Sympathetic impulses to heart cause HR, contractility, and CO. © 2013 Pearson Education, Inc. 3 Impulses from baroreceptors activate cardioacceleratory center (and inhibit cardioinhibitory center) and stimulate vasomotor center. Slide 1 Short-term Mechanisms: Chemoreceptor Reflexes • Chemoreceptors in aortic arch and large arteries of neck detect increase in CO2, or drop in pH or O2 • Cause increased blood pressure by – Signaling cardioacceleratory center increase CO – Signaling vasomotor center increase vasoconstriction © 2013 Pearson Education, Inc. Short-term Mechanisms: Influence of Higher Brain Centers • Reflexes in medulla • Hypothalamus and cerebral cortex can modify arterial pressure via relays to medulla • Hypothalamus increases blood pressure during stress • Hypothalamus mediates redistribution of blood flow during exercise and changes in body temperature © 2013 Pearson Education, Inc. Short-term Mechanisms: Hormonal Controls • Short term regulation via changes in peripheral resistance • Long term regulation via changes in blood volume © 2013 Pearson Education, Inc. Short-term Mechanisms: Hormonal Controls • Cause increased blood pressure – Epinephrine and norepinephrine from adrenal gland increased CO and vasoconstriction – Angiotensin II stimulates vasoconstriction – High ADH levels cause vasoconstriction • Cause lowered blood pressure – Atrial natriuretic peptide causes decreased blood volume by antagonizing aldosterone © 2013 Pearson Education, Inc. Figure 19.10 Direct and indirect (hormonal) mechanisms for renal control of blood pressure. Direct renal mechanism Arterial pressure Indirect renal mechanism (renin-angiotensin-aldosterone) Initial stimulus Arterial pressure Physiological response Result Inhibits baroreceptors Sympathetic nervous system activity Filtration by kidneys Angiotensinogen Renin release from kidneys Angiotensin I Angiotensin converting enzyme (ACE) Angiotensin II Urine formation Adrenal cortex ADH release by posterior pituitary Thirst via hypothalamus Secretes Aldosterone Blood volume Sodium reabsorption by kidneys Water reabsorption by kidneys Water intake Blood volume Mean arterial pressure © 2013 Pearson Education, Inc. Mean arterial pressure Vasoconstriction; peripheral resistance Long-term Mechanisms: Renal Regulation • • • Baroreceptors quickly adapt to chronic high or low BP so are ineffective Long-term mechanisms control BP by altering blood volume via kidneys Kidneys regulate arterial blood pressure 1. Direct renal mechanism 2. Indirect renal (renin-angiotensin-aldosterone) mechanism © 2013 Pearson Education, Inc. Direct Renal Mechanism • Alters blood volume independently of hormones – Increased BP or blood volume causes elimination of more urine, thus reducing BP – Decreased BP or blood volume causes kidneys to conserve water, and BP rises © 2013 Pearson Education, Inc. Indirect Mechanism • The renin-angiotensin-aldosterone mechanism – Arterial blood pressure release of renin – Renin catalyzes conversion of angiotensinogen from liver to angiotensin I – Angiotensin converting enzyme, especially from lungs, converts angiotensin I to angiotensin II © 2013 Pearson Education, Inc. Functions of Angiotensin II • Increases blood volume – Stimulates aldosterone secretion – Causes ADH release – Triggers hypothalamic thirst center • Causes vasoconstriction directly increasing blood pressure © 2013 Pearson Education, Inc. Figure 19.10 Direct and indirect (hormonal) mechanisms for renal control of blood pressure. Direct renal mechanism Arterial pressure Indirect renal mechanism (renin-angiotensin-aldosterone) Initial stimulus Arterial pressure Physiological response Result Inhibits baroreceptors Sympathetic nervous system activity Filtration by kidneys Angiotensinogen Renin release from kidneys Angiotensin I Angiotensin converting enzyme (ACE) Angiotensin II Urine formation Adrenal cortex ADH release by posterior pituitary Thirst via hypothalamus Secretes Aldosterone Blood volume Sodium reabsorption by kidneys Water reabsorption by kidneys Water intake Blood volume Mean arterial pressure © 2013 Pearson Education, Inc. Mean arterial pressure Vasoconstriction; peripheral resistance Figure 19.11 Factors that increase MAP. Activity of muscular pump and respiratory pump Release of ANP Fluid loss from hemorrhage, excessive sweating Crisis stressors: exercise, trauma, body temperature Conservation of Na+ and water by kidneys Blood volume Blood pressure Blood pH O2 CO2 Blood volume Baroreceptors Chemoreceptors Venous return Activation of vasomotor and cardioacceleratory centers in brain stem Stroke volume Heart rate Vasomotor tone; bloodborne chemicals (epinephrine, NE, ADH, angiotensin II) Diameter of blood vessels Cardiac output Physiological response © 2013 Pearson Education, Inc. Blood viscosity Body size Blood vessel length Peripheral resistance Initial stimulus Result Dehydration, high hematocrit Mean arterial pressure (MAP) Monitoring Circulatory Efficiency • Vital signs: pulse and blood pressure, along with respiratory rate and body temperature • Pulse: pressure wave caused by expansion and recoil of arteries • Radial pulse (taken at the wrist) routinely used • Pressure points where arteries close to body surface – Can be compressed to stop blood flow © 2013 Pearson Education, Inc. Figure 19.12 Body sites where the pulse is most easily palpated. Superficial temporal artery Facial artery Common carotid artery Brachial artery Radial artery Femoral artery Popliteal artery Posterior tibial artery © 2013 Pearson Education, Inc. Dorsalis pedis artery Measuring Blood Pressure • Systemic arterial BP – Measured indirectly by auscultatory method using a sphygmomanometer – Pressure increased in cuff until it exceeds systolic pressure in brachial artery – Pressure released slowly and examiner listens for sounds of Korotkoff with a stethoscope © 2013 Pearson Education, Inc. Measuring Blood Pressure • Systolic pressure, normally less than 120 mm Hg, is pressure when sounds first occur as blood starts to spurt through artery • Diastolic pressure, normally less than 80 mm Hg, is pressure when sounds disappear because artery no longer constricted; blood flowing freely © 2013 Pearson Education, Inc. Variations in Blood Pressure • Transient elevations occur during changes in posture, physical exertion, emotional upset, fever. • Age, sex, weight, race, mood, and posture may cause BP to vary © 2013 Pearson Education, Inc. Alterations in Blood Pressure • Hypertension: high blood pressure – Sustained elevated arterial pressure of 140/90 or higher – Prehypertension if values elevated but not yet in hypertension range • May be transient adaptations during fever, physical exertion, and emotional upset • Often persistent in obese people © 2013 Pearson Education, Inc. Homeostatic Imbalance: Hypertension • Prolonged hypertension major cause of heart failure, vascular disease, renal failure, and stroke – Heart must work harder myocardium enlarges, weakens, becomes flabby – Also accelerates atherosclerosis © 2013 Pearson Education, Inc. Primary or Essential Hypertension • 90% of hypertensive conditions • No underlying cause identified – Risk factors include heredity, diet, obesity, age, diabetes mellitus, stress, and smoking • No cure but can be controlled – Restrict salt, fat, cholesterol intake – Increase exercise, lose weight, stop smoking – Antihypertensive drugs © 2013 Pearson Education, Inc. Homeostatic Imbalance: Hypertension • Secondary hypertension less common – Due to identifiable disorders including obstructed renal arteries, kidney disease, and endocrine disorders such as hyperthyroidism and Cushing's syndrome – Treatment focuses on correcting underlying cause © 2013 Pearson Education, Inc. Alterations in Blood Pressure • Hypotension: low blood pressure – Blood pressure below 90/60 mm Hg – Usually not a concern • Only if leads to inadequate blood flow to tissues – Often associated with long life and lack of cardiovascular illness © 2013 Pearson Education, Inc. Homeostatic Imbalance: Hypotension • Orthostatic hypotension: temporary low BP and dizziness when suddenly rising from sitting or reclining position • Chronic hypotension: hint of poor nutrition and warning sign for Addison's disease or hypothyroidism • Acute hypotension: important sign of circulatory shock; threat for surgical patients and those in ICU © 2013 Pearson Education, Inc. Blood Flow Through Body Tissues • Tissue perfusion involved in – Delivery of O2 and nutrients to, and removal of wastes from, tissue cells – Gas exchange (lungs) – Absorption of nutrients (digestive tract) – Urine formation (kidneys) • Rate of flow is precisely right amount to provide proper function © 2013 Pearson Education, Inc. Figure 19.13 Distribution of blood flow at rest and during strenuous exercise. 750 750 Brain 750 Heart 250 12,500 1200 Skeletal muscles 500 Skin Kidneys 1100 Abdomen 1400 1900 Other 600 Total blood flow at rest 5800 ml/min 600 600 400 © 2013 Pearson Education, Inc. Total blood flow during strenuous exercise 17,500 ml/min Velocity of Blood Flow • Changes as travels through systemic circulation • Inversely related to total cross-sectional area • Fastest in aorta; slowest in capillaries; increases in veins • Slow capillary flow allows adequate time for exchange between blood and tissues © 2013 Pearson Education, Inc. Figure 19.14 Blood flow velocity and total cross-sectional area of vessels. Relative crosssectional area of different vessels of the vascular bed 5000 4000 Total area (cm2) of the 3000 vascular 2000 bed 1000 0 Velocity of blood flow (cm/s) © 2013 Pearson Education, Inc. 50 40 30 20 10 0 Autoregulation • Automatic adjustment of blood flow to each tissue relative to its varying requirements • Controlled intrinsically by modifying diameter of local arterioles feeding capillaries – Independent of MAP, which is controlled as needed to maintain constant pressure • Organs regulate own blood flow by varying resistance of own arterioles © 2013 Pearson Education, Inc. Autoregulation • Two types of autoregulation – Metabolic controls – Myogenic controls • Both determine final autoregulatory response © 2013 Pearson Education, Inc. Metabolic Controls • Vasodilation of arterioles and relaxation of precapillary sphincters occur in response to – Declining tissue O2 – Substances from metabolically active tissues (H+, K+, adenosine, and prostaglandins) and inflammatory chemicals © 2013 Pearson Education, Inc. Metabolic Controls • Effects – Relaxation of vascular smooth muscle – Release of NO (powerful vasodilator) by endothelial cells • Endothelins released from endothelium are potent vasoconstrictors • NO and endothelins balanced unless blood flow inadequate, then NO wins • Inflammatory chemicals also cause vasodilation © 2013 Pearson Education, Inc. Myogenic Controls • Myogenic responses keep tissue perfusion constant despite most fluctuations in systemic pressure • Vascular smooth muscle responds to stretch – Passive stretch (increased intravascular pressure) promotes increased tone and vasoconstriction – Reduced stretch promotes vasodilation and increases blood flow to the tissue © 2013 Pearson Education, Inc. Figure 19.15 Intrinsic and extrinsic control of arteriolar smooth muscle in the systemic circulation. Vasodilators Metabolic O2 CO2 H+ K+ • Prostaglandins • Adenosine • Nitric oxide Neuronal Sympathetic tone Hormonal • Atrial natriuretic peptide Extrinsic mechanisms Intrinsic mechanisms (autoregulation) Vasoconstrictors • Metabolic or myogenic controls • Distribute blood flow to individual organs and tissues as needed Myogenic • Stretch © 2013 Pearson Education, Inc. Neuronal Sympathetic tone Metabolic Hormonal • Endothelins • Angiotensin II • Antidiuretic hormone • Epinephrine • Norepinephrine • Neuronal or hormonal controls • Maintain mean arterial pressure (MAP) • Redistribute blood during exercise and thermoregulation Long-term Autoregulation • Occurs when short-term autoregulation cannot meet tissue nutrient requirements • Angiogenesis – Number of vessels to region increases and existing vessels enlarge – Common in heart when coronary vessel occluded, or throughout body in people in high-altitude areas © 2013 Pearson Education, Inc. Blood Flow: Skeletal Muscles • Varies with fiber type and activity – At rest, myogenic and general neural mechanisms predominate - maintain ~ 1L /minute – During muscle activity • Active or exercise hyperemia - blood flow increases in direct proportion to metabolic activity • Local controls override sympathetic vasoconstriction • Muscle blood flow can increase 10 © 2013 Pearson Education, Inc. Blood Flow: Brain • Blood flow to brain constant as neurons intolerant of ischemia; averages 750 ml/min • Metabolic controls – Decreased pH of increased carbon dioxide cause marked vasodilation • Myogenic controls – Decreased MAP causes cerebral vessels to dilate – Increased MAP causes cerebral vessels to constrict © 2013 Pearson Education, Inc. Blood Flow: Brain • Brain vulnerable under extreme systemic pressure changes – MAP below 60 mm Hg can cause syncope (fainting) – MAP above 160 can result in cerebral edema © 2013 Pearson Education, Inc. Blood Flow: Skin • Blood flow through skin – Supplies nutrients to cells (autoregulation in response to O2 need) – Helps regulate body temperature (neurally controlled) – primary function – Provides a blood reservoir (neurally controlled) © 2013 Pearson Education, Inc. Blood Flow: Skin • Blood flow to venous plexuses below skin surface regulates body temperature – Varies from 50 ml/min to 2500 ml/min, depending on body temperature – Controlled by sympathetic nervous system reflexes initiated by temperature receptors and central nervous system © 2013 Pearson Education, Inc. Temperature Regulation • As temperature rises (e.g., heat exposure, fever, vigorous exercise) – Hypothalamic signals reduce vasomotor stimulation of skin vessels – Warm blood flushes into capillary beds – Heat radiates from skin © 2013 Pearson Education, Inc. Temperature Regulation • Sweat also causes vasodilation via bradykinin in perspiration – Bradykinin stimulates NO release • As temperature decreases, blood is shunted to deeper, more vital organs © 2013 Pearson Education, Inc. Blood Flow: Lungs • Pulmonary circuit unusual – Pathway short – Arteries/arterioles more like veins/venules (thin walled, with large lumens) – Arterial resistance and pressure are low (24/10 mm Hg) © 2013 Pearson Education, Inc. Blood Flow: Lungs • Autoregulatory mechanism opposite that in most tissues – Low O2 levels cause vasoconstriction; high levels promote vasodilation • Allows blood flow to O2-rich areas of lung © 2013 Pearson Education, Inc. Blood Flow: Heart • During ventricular systole – Coronary vessels are compressed • Myocardial blood flow ceases • Stored myoglobin supplies sufficient oxygen • During diastole high aortic pressure forces blood through coronary circulation • At rest ~ 250 ml/min; control probably myogenic © 2013 Pearson Education, Inc. Blood Flow: Heart • During strenuous exercise – Coronary vessels dilate in response to local accumulation of vasodilators – Blood flow may increase three to four times • Important–cardiac cells use 65% of O2 delivered so increased blood flow provides more O2 © 2013 Pearson Education, Inc. Blood Flow Through Capillaries • Vasomotion – Slow, intermittent flow – Reflects on/off opening and closing of precapillary sphincters © 2013 Pearson Education, Inc. Capillary Exchange of Respiratory Gases and Nutrients • Diffusion down concentration gradients – O2 and nutrients from blood to tissues – CO2 and metabolic wastes from tissues to blood • Lipid-soluble molecules diffuse directly through endothelial membranes • Water-soluble solutes pass through clefts and fenestrations • Larger molecules, such as proteins, are actively transported in pinocytotic vesicles or caveolae © 2013 Pearson Education, Inc. Figure 19.16 Capillary transport mechanisms. (1 of 2) Pinocytotic vesicles Red blood cell in lumen Endothelial cell Fenestration (pore) Endothelial cell nucleus Basement membrane © 2013 Pearson Education, Inc. Tight junction Intercellular cleft Figure 19.16 Capillary transport mechanisms. (2 of 2) Lumen Caveolae Pinocytotic vesicles Intercellular cleft Endothelial fenestration (pore) Basement membrane 1 Diffusion through membrane (lipid-soluble substances) © 2013 Pearson Education, Inc. 2 Movement through intercellular clefts (watersoluble substances) 4 Transport via vesicles or caveolae (large substances) 3 Movement through fenestrations (water-soluble substances) Fluid Movements: Bulk Flow • Fluid leaves capillaries at arterial end; most returns to blood at venous end – Extremely important in determining relative fluid volumes in blood and interstitial space • Direction and amount of fluid flow depend on two opposing forces: hydrostatic and colloid osmotic pressures © 2013 Pearson Education, Inc. Hydrostatic Pressures • Capillary hydrostatic pressure (HPc) (capillary blood pressure) – Tends to force fluids through capillary walls – Greater at arterial end (35 mm Hg) of bed than at venule end (17 mm Hg) • Interstitial fluid hydrostatic pressure (HPif) – Pressure that would push fluid into vessel – Usually assumed to be zero because of lymphatic vessels © 2013 Pearson Education, Inc. Colloid Osmotic Pressures • Capillary colloid osmotic pressure (oncotic pressure) (OPc) – Created by nondiffusible plasma proteins, which draw water toward themselves – ~26 mm Hg • Interstitial fluid osmotic pressure (OPif) – Low (~1 mm Hg) due to low protein content © 2013 Pearson Education, Inc. Hydrostatic-osmotic Pressure Interactions: Net Filtration Pressure (NFP) • NFP—comprises all forces acting on capillary bed – NFP = (HPc + OPif) – (HPif + OPc) • Net fluid flow out at arterial end • Net fluid flow in at venous end • More leaves than is returned – Excess fluid returned to blood via lymphatic system © 2013 Pearson Education, Inc. Figure 19.17 Bulk fluid flow across capillary walls causes continuous mixing of fluid between the plasma and the interstitial fluid compartments, and maintains the interstitial environment. (1 of 5) The big picture Fluid filters from capillaries at their arteriolar end and flows through the interstitial space. Most is reabsorbed at the venous end. Arteriole Fluid moves through the interstitial space. For all capillary beds, 20 L of fluid is filtered out per day—almost 7 times the total plasma volume! Net filtration pressure (NFP) determines the direction of fluid movement. Two kinds of pressure drive fluid flow: Hydrostatic pressure (HP) • Due to fluid pressing against a boundary • HP “pushes” fluid across the boundary • In blood vessels, is due to blood pressure Osmotic pressure (OP) • Due to nondiffusible solutes that cannot cross the boundary • OP “pulls” fluid across the boundary • In blood vessels, is due to plasma proteins Piston Boundary “Pushes” Solute molecules (proteins) 17 L of fluid per day is reabsorbed into the capillaries at the venous end. Boundary “Pulls” Venule © 2013 Pearson Education, Inc. About 3 L per day of fluid (and any leaked proteins) are removed by the lymphatic system (see Chapter 20). Lymphatic capillary Figure 19.17 Bulk fluid flow across capillary walls causes continuous mixing of fluid between the plasma and the interstitial fluid compartments, and maintains the interstitial environment. (3 of 5) Net filtration pressure (NFP) determines the direction of fluid movement. Two kinds of pressure drive fluid flow: Hydrostatic pressure (HP) Osmotic pressure (OP) • Due to fluid pressing against a boundary • HP “pushes” fluid across the boundary • In blood vessels, is due to blood pressure • Due to nondiffusible solutes that cannot cross the boundary • OP “pulls” fluid across the boundary • In blood vessels, is due to plasma proteins Piston Solute molecules (proteins) Boundary “Pushes” © 2013 Pearson Education, Inc. “Pulls” Boundary Figure 19.17 Bulk fluid flow across capillary walls causes continuous mixing of fluid between the plasma and the interstitial fluid compartments, and maintains the interstitial environment. (4 of 5) How do the pressures drive fluid flow across a capillary? Net filtration occurs at the arteriolar end of a capillary. Capillary Hydrostatic pressure in capillary “pushes” fluid out of capillary. Osmotic pressure in capillary “pulls” fluid into capillary. Boundary (capillary wall) HPc = 35 mm Hg OPc = 26 mm Hg HPif = 0 mm Hg OPif = 1 mm Hg NFP = 10 mm Hg © 2013 Pearson Education, Inc. Interstitial fluid Hydrostatic pressure in interstitial fluid “pushes” fluid into capillary. Osmotic pressure in interstitial fluid “pulls” fluid out of capillary. To determine the pressure driving the fluid out of the capillary at any given point, we calculate the net filtration pressure (NFP)––the outward pressures (HPc and OPif) minus the inward pressures (HPif and OPc). So, NFP = (HPc + OPif) – (HPif + OPc) = (35 + 1) – (0 + 26) = 10 mm Hg (net outward pressure) As a result, fluid moves from the capillary into the interstitial space. Figure 19.17 Bulk fluid flow across capillary walls causes continuous mixing of fluid between the plasma and the interstitial fluid compartments, and maintains the interstitial environment. (5 of 5) Net reabsorption occurs at the venous end of a capillary. Boundary (capillary wall) Capillary Interstitial fluid Hydrostatic pressure in capillary HPc = 17 mm Hg “pushes” fluid out of capillary. The pressure has dropped because of resistance encountered along the capillaries. Osmotic pressure in capillary “pulls” fluid into capillary. OPc = 26 mm Hg HPif = 0 mm Hg Hydrostatic pressure in interstitial fluid “pushes” fluid into capillary. OPif = 1 mm Hg Osmotic pressure in interstitial fluid “pulls” fluid out of capillary. NFP= –8 mm Hg © 2013 Pearson Education, Inc. Again, we calculate the NFP: NFP = (HPc + OPif) – (HPif + OPc) = (17 + 1) – (0 + 26) = –8 mm Hg (net inward pressure) Notice that the NFP at the venous end is a negative number. This means that reabsorption, not filtration, is occurring and so fluid moves from the interstitial space into the capillary. Circulatory Shock • Any condition in which – Blood vessels inadequately filled – Blood cannot circulate normally • Results in inadequate blood flow to meet tissue needs © 2013 Pearson Education, Inc. Circulatory Shock • Hypovolemic shock: results from largescale blood loss • Vascular shock: results from extreme vasodilation and decreased peripheral resistance • Cardiogenic shock results when an inefficient heart cannot sustain adequate circulation © 2013 Pearson Education, Inc. Figure 19.18 Events and signs of hypovolemic shock. Acute bleeding (or other events that reduce blood volume) leads to: 1. Inadequate tissue perfusion resulting in O2 and nutrients to cells Initial stimulus Physiological response Signs and symptoms Result 2. Anaerobic metabolism by cells, so lactic acid accumulates 3. Movement of interstitial fluid into blood, so tissues dehydrate Chemoreceptors activated (by in blood pH) Baroreceptor firing reduced (by blood volume and pressure) Hypothalamus activated (by blood pressure) Brain Minor effect Major effect Respiratory centers activated Cardioacceleratory and vasomotor centers activated Heart rate Sympathetic nervous system activated ADH released Neurons depressed by pH Intense vasoconstriction (only heart and brain spared) Central nervous system depressed Kidneys Renal blood flow Adrenal cortex Renin released Angiotensin II produced in blood Aldosterone released Rate and depth of breathing CO2 blown off; blood pH rises © 2013 Pearson Education, Inc. Tachycardia; weak, thready pulse Kidneys retain salt and water Skin becomes cold, clammy, and cyanotic Blood pressure maintained; if fluid volume continues to decrease, BP ultimately drops. BP is a late sign. Water retention Urine output Thirst Restlessness (early sign) Coma (late sign) Circulatory Pathways: Blood Vessels of the Body • Two main circulations – Pulmonary circulation: short loop that runs from heart to lungs and back to heart – Systemic circulation: long loop to all parts of body and back to heart © 2013 Pearson Education, Inc. Figure 19.19a Pulmonary circulation. Pulmonary capillaries of the R. lung R. pulmonary artery Pulmonary capillaries of the L. lung L. pulmonary artery To systemic circulation Pulmonary trunk R. pulmonary veins From systemic circulation LA RA L. pulmonary veins RV © 2013 Pearson Education, Inc. Schematic flowchart. LV Figure 19.19 Pulmonary circulation. Pulmonary capillaries of the R. lung Pulmonary capillaries of the L. lung R. pulmonary L. pulmonary artery artery To systemic circulation Pulmonary trunk R. pulmonary veins From systemic circulation RA LA RV LV L. pulmonary veins Schematic flowchart. Left pulmonary artery Air-filled alveolus of lung Aortic arch Pulmonary trunk Right pulmonary artery Three lobar arteries to right lung Pulmonary capillary Gas exchange Two lobar arteries to left lung Pulmonary veins Pulmonary veins Right atrium Left atrium Right ventricle Left ventricle Illustration. The pulmonary arterial system is shown in blue to indicate that the blood it carries is oxygen-poor. The pulmonary venous drainage is shown in red to indicate that the blood it transports is oxygen-rich. © 2013 Pearson Education, Inc. Figure 19.20 Schematic flowchart showing an overview of the systemic circulation. Common carotid arteries to head and subclavian arteries to upper limbs Capillary beds of head and upper limbs Superior vena cava Aortic arch Aorta RA LA RV LV Azygos system Venous drainage Inferior vena cava Thoracic aorta Arterial blood Capillary beds of mediastinal structures and thorax walls Diaphragm Abdominal aorta Inferior vena cava © 2013 Pearson Education, Inc. Capillary beds of digestive viscera, spleen, pancreas, kidneys Capillary beds of gonads, pelvis, and lower limbs Differences Between Arteries and Veins Arteries Veins Delivery Blood pumped into single systemic artery—the aorta Blood returns via superior and interior venae cavae and the coronary sinus Location Deep, and protected by tissues Both deep and superficial Pathways Fairly distinct Numerous interconnections Supply/drainage Predictable supply Usually similar to arteries, except dural sinuses and hepatic portal circulation © 2013 Pearson Education, Inc. Developmental Aspects • Endothelial lining arises from mesodermal cells in blood islands • Blood islands form rudimentary vascular tubes, guided by cues • Vascular endothelial growth factor determines whether vessel becomes artery or vein • The heart pumps blood by the 4th week of development © 2013 Pearson Education, Inc. Developmental Aspects • Fetal shunts (foramen ovale and ductus arteriosus) bypass nonfunctional lungs • Ductus venosus bypasses liver • Umbilical vein and arteries circulate blood to and from placenta • Congenital vascular problems rare © 2013 Pearson Education, Inc. Developmental Aspects • Vessel formation occurs – To support body growth – For wound healing – To rebuild vessels lost during menstrual cycles • With aging, varicose veins, atherosclerosis, and increased blood pressure may arise © 2013 Pearson Education, Inc. Figure 19.21a Major arteries of the systemic circulation. R. internal carotid artery R. external carotid artery R. common carotid – right side of head and neck R. vertebral R. axillary R. subclavian – neck and R. upper limb Brachiocephalic – head, neck, and R. upper limb Arteries of R. upper limb L. external carotid artery L. internal carotid artery L. common carotid – left side of head and neck L. vertebral L. subclavian – neck and L. upper limb Aortic arch L. axillary Arteries of L. upper limb Ascending aorta – L. ventricle to sternal angle Thoracic aorta T5–T12 (diaphragm) L. and R. coronary arteries L. ventricle of heart Visceral branches Mediastinal – posterior mediastinum Esophageal – esophagus Bronchial – lungs and bronchi Parietal branches Pericardial – pericardium Posterior intercostals – intercostal muscles, spinal cord, vertebrae, pleurae, skin Superior phrenics – posterior and superior diaphragm Diaphragm Abdominal aorta T12 (diaphragm)–L4 Visceral branches Gonadal – testes or ovaries Suprarenal – adrenal glands and Renal – kidneys Superior and inferior mesenterics – small intestine – colon Parietal branches Celiac trunk – liver – gallbladder – spleen – stomach – esophagus – duodenum R. common iliac – pelvis and R. lower limb Arteries of R. lower limb Schematic flowchart © 2013 Pearson Education, Inc. Inferior phrenics – inferior diaphragm Lumbars – posterior abdominal wall Median sacral – sacrum – coccyx L. common iliac – pelvis and L. lower limb Arteries of L. lower limb Figure 19.21b Major arteries of the systemic circulation. Arteries of the head and trunk Internal carotid artery External carotid artery Common carotid arteries Vertebral artery Subclavian artery Brachiocephalic trunk Arteries that supply the upper limb Subclavian artery Axillary artery Brachial artery Aortic arch Ascending aorta Coronary artery Celiac trunk Abdominal aorta Superior mesenteric artery Renal artery Gonadal artery Radial artery Ulnar artery Deep palmar arch Superficial palmar arch Digital arteries Arteries that supply the lower limb External iliac artery Inferior mesenteric artery Femoral artery Common iliac artery Popliteal artery Internal iliac artery Anterior tibial artery Posterior tibial artery Illustration, anterior view © 2013 Pearson Education, Inc. Arcuate artery Figure 19.22a Arteries of the head, neck, and brain. R. and L. anterior cerebral arteries R. Middle cerebral artery Anterior communicating artery Cerebral arterial circle R. and L. Posterior communicating arteries Ophthalmic artery Superficial temporal artery R. posterior cerebral artery Basilar artery R. and L. vertebral arteries Maxillary artery Occipital artery R. and L. internal carotid arteries Facial artery Lingual artery R. and L. external carotid arteries Superior thyroid artery R. and L. common carotid arteries R. and L. subclavian arteries Brachiocephalic trunk Aortic arch © 2013 Pearson Education, Inc. Schematic flowchart Figure 19.22b Arteries of the head, neck, and brain. Ophthalmic artery Basilar artery Vertebral artery Internal carotid artery External carotid artery Common carotid artery Thyrocervical trunk Costocervical trunk Subclavian artery Axillary artery Arteries of the head and neck, right aspect © 2013 Pearson Education, Inc. Branches of the external carotid artery • Superficial temporal artery • Maxillary artery • Occipital artery • Facial artery • Lingual artery • Superior thyroid artery Larynx Thyroid gland (overlying trachea) Clavicle (cut) Brachiocephalic trunk Internal thoracic artery Figure 19.22c Arteries of the head, neck, and brain. © 2013 Pearson Education, Inc. Colorized arteriograph of the arterial supply of the brain Figure 19.22d Arteries of the head, neck, and brain. Anterior Cerebral arterial circle (circle of Willis) Frontal lobe Optic chiasma • Anterior communicating artery Middle cerebral artery • Anterior cerebral artery Internal carotid artery • Posterior communicating artery Mammillary body • Posterior cerebral artery Basilar artery Temporal lobe Vertebral artery Pons Occipital lobe Cerebellum Posterior Major arteries serving the brain (inferior view, right side of cerebellum and part of right temporal lobe removed) © 2013 Pearson Education, Inc. Figure 19.23a Arteries of the right upper limb and thorax. R. vertebral artery R. common carotid artery L. common carotid artery Thyrocervical trunk L. vertebral artery L. subclavian artery Suprascapular artery R. subclavian artery. Axillary artery Thoracoacromial artery Thoracoacromial artery (pectoral branch) Aortic arch Anterior and posterior circumflex humeral arteries Brachial artery Deep artery of arm Brachiocephalic trunk Internal thoracic artery Anterior intercostal arteries Lateral thoracic artery Subscapular artery Anastomosis Common interosseus artery Radial artery Deep palmar arch Ulnar artery Metacarpal arteries Superficial palmar arch Digital arteries © 2013 Pearson Education, Inc. Schematic flowchart Costocervical trunk Thoracic aorta Posterior intercostal arteries Figure 19.23b Arteries of the right upper limb and thorax. Vertebral artery Thyrocervical trunk Costocervical trunk Suprascapular artery Thoracoacromial artery Axillary artery Subscapular artery Posterior circumflex humeral artery Anterior circumflex humeral artery Common carotid arteries Right subclavian artery Left subclavian artery Brachiocephalic trunk Posterior intercostal arteries Anterior intercostal artery Internal thoracic artery Brachial artery Deep artery of arm Lateral thoracic artery Thoracic aorta Common interosseous artery Radial artery Ulnar artery Deep palmar arch Superficial palmar arch Digital arteries Illustration, anterior view © 2013 Pearson Education, Inc. Figure 19.24a Arteries of the abdomen. Diaphragm Abdominal aorta Inferior phrenic arteries L. gastric artery R. gastric artery Common hepatic artery Hepatic artery proper L Splenic artery Gastroduodenal artery R Celiac trunk R. gastroepiploic artery Middle suprarenal arteries L. gastroepiploic artery Intestinal arteries Middle colic artery Superior mesenteric artery R. colic artery Renal arteries Gonadal arteries Ileocolic artery Sigmoidal arteries Inferior mesenteric artery Lumbar arteries L. colic artery Superior rectal artery Median sacral artery Common iliac arteries Schematic flowchart. © 2013 Pearson Education, Inc. Figure 19.24b Arteries of the abdomen. Liver (cut) Inferior vena cava Celiac trunk Common hepatic artery Hepatic artery proper Gastroduodenal artery Right gastric artery Diaphragm Esophagus Left gastric artery Stomach Splenic artery Left gastroepiploic artery Spleen Gallbladder Pancreas (major portion lies posterior to stomach) Right gastroepiploic artery Duodenum Abdominal aorta Superior mesenteric artery The celiac trunk and its major branches. The left half of the liver has been removed. © 2013 Pearson Education, Inc. Figure 19.24c Arteries of the abdomen. Hiatus (opening) for inferior vena cava Hiatus (opening) for esophagus Diaphragm Inferior phrenic artery Adrenal (suprarenal) gland Middle suprarenal artery Celiac trunk Renal artery Kidney Superior mesenteric artery Abdominal aorta Lumbar arteries Ureter Median sacral artery Major branches of the abdominal aorta. © 2013 Pearson Education, Inc. Gonadal (testicular or ovarian) artery Inferior mesenteric artery Common iliac artery Figure 19.24d Arteries of the abdomen. Celiac trunk Superior mesenteric artery Branches of the superior mesenteric artery • Middle colic artery • Intestinal arteries • Right colic artery • Ileocolic artery Ascending colon Right common iliac artery Ileum Transverse colon Aorta Inferior mesenteric artery Branches of the inferior mesenteric artery • Left colic artery • Sigmoidal arteries • Superior rectal artery Descending colon Cecum Appendix Distribution of the superior and inferior mesenteric arteries. The transverse colon has been pulled superiorly. © 2013 Pearson Education, Inc. Sigmoid colon Rectum Figure 19.25a Arteries of the right pelvis and lower limb. Abdominal aorta Superior gluteal artery Internal iliac artery Inferior gluteal artery Internal pudendal Common iliac artery Obturator artery Deep artery of thigh Medial circumflex femoral artery Lateral circumflex femoral artery External iliac artery Femoral artery Adductor hiatus Arterial anastomosis Popliteal artery Anterior tibial artery Posterior tibial artery Fibular (peroneal) artery Dorsalis pedis artery Lateral plantar artery Lateral plantar artery Medial plantar artery Arcuate artery Plantar arch Dorsal metatarsal arteries Schematic flowchart © 2013 Pearson Education, Inc. Plantar metatarsal arteries Figure 19.25b Arteries of the right pelvis and lower limb. Common iliac artery Internal iliac artery Superior gluteal artery External iliac artery Deep artery of thigh Lateral circumflex femoral artery Medial circumflex femoral artery Obturator artery Femoral artery Adductor hiatus Popliteal artery Anterior tibial artery Posterior tibial artery Fibular artery Dorsalis pedis artery Arcuate artery Dorsal metatarsal arteries © 2013 Pearson Education, Inc. Anterior view Figure 19.25c Arteries of the right pelvis and lower limb. Popliteal artery Anterior tibial artery Posterior tibial artery Lateral plantar artery Medial plantar artery © 2013 Pearson Education, Inc. Posterior view Fibular artery Dorsalis pedis artery (from top of foot) Plantar arch Figure 19.26a Major veins of the systemic circulation. Veins of R. upper limb R. axillary R. external jugular – superficial head and neck R. vertebral – cervical spinal cord and vertebrae Intracranial dural venous sinuses R. internal jugular – dural venous sinuses of the brain R. subclavian – R. head, neck, and upper limb Same as R. brachiocephalic R. brachiocephalic – R. side of head and R. upper limb L. brachiocephalic – L. side of head and L. upper limb Superior vena cava – runs from union of brachiocephalic veins behind manubrium to R. atrium Azygos system – drains much of thorax R. atrium of heart Diaphragm Inferior vena cava – runs from junction of common iliac veins at L5 to R. atrium of heart R. suprarenal (L. suprarenal drains into L. renal vein) – adrenal glands R. gonadal (L. gonadal drains into L. renal vein) – testis or ovary R. common iliac – pelvis and R. lower limb Veins of R. lower limb © 2013 Pearson Education, Inc. Schematic flowchart. L., R., and middle hepatic veins – liver L. and R. renal veins – kidneys Lumbar veins (several pairs) – posterior abdominal wall L. common iliac – pelvis and L. lower limb Veins of L. lower limb Figure 19.26b Major veins of the systemic circulation. Veins of the head and trunk Dural venous sinuses External jugular vein Vertebral vein Internal jugular vein Right and left brachiocephalic veins Superior vena cava Great cardiac vein Hepatic veins Splenic vein Hepatic portal vein Renal vein Superior mesenteric vein Inferior mesenteric vein Inferior vena cava Common iliac vein Internal iliac vein Veins that drain the upper limb Subclavian vein Axillary vein Cephalic vein Brachial vein Basilic vein Median cubital vein Ulnar vein Radial vein Digital veins Veins that drain the lower limb External iliac vein Femoral vein Great saphenous vein Popliteal vein Posterior tibial vein Anterior tibial vein Small saphenous vein Dorsal venous arch Dorsal metatarsal veins Illustration, anterior view. The vessels of the pulmonary circulation are not shown. © 2013 Pearson Education, Inc. Figure 19.27a Venous drainage of the head, neck, and brain. Superior sagittal sinus Inferior sagittal sinus Occipital vein Superficial temporal vein Straight sinus Transverse sinus Ophthalmic vein Cavernous sinus Facial vein Posterior auricular vein Sigmoid sinus Internal jugular vein External jugular vein Superior thyroid vein Vertebral vein Middle thyroid vein Brachiocephalic veins Subclavian vein Superior vena cava Schematic flowchart © 2013 Pearson Education, Inc. Figure 19.27b Venous drainage of the head, neck, and brain. Ophthalmic vein Superficial temporal vein Facial vein Occipital vein Posterior auricular vein External jugular vein Vertebral vein Internal jugular vein Superior and middle thyroid veins Brachiocephalic vein Subclavian vein Superior vena cava Veins of the head and neck, right superficial aspect © 2013 Pearson Education, Inc. Figure 19.27c Venous drainage of the head, neck, and brain. Superior sagittal sinus Falx cerebri Inferior sagittal sinus Straight sinus Cavernous sinus Transverse sinuses Sigmoid sinus Jugular foramen Right internal jugular vein Dural venous sinuses of the brain © 2013 Pearson Education, Inc. Figure 19.28a Veins of the thorax and right upper limb. Internal Subclavian jugular vein vein External Brachiocephalic jugular vein veins Axillary vein Superior vena cava Accessory hemiazygos vein Median cubital vein Azygos vein Brachial vein Hemiazygos vein Right and left posterior intercostal veins Cephalic vein Median antebrachial vein Radial vein Basilic vein Ulnar vein Deep venous palmar arch Metacarpal veins Superficial venous palmar arch Digital veins Schematic flowchart © 2013 Pearson Education, Inc. Figure 19.28b Veins of the thorax and right upper limb. Brachiocephalic veins Right subclavian vein Axillary vein Brachial vein Cephalic vein Basilic vein Internal jugular vein External jugular vein Left subclavian vein Superior vena cava Azygos vein Accessory hemiazygos vein Hemiazygos vein Posterior intercostals Inferior vena cava Ascending lumbar vein Median cubital vein Median antebrachial vein Cephalic vein Radial vein Anterior view © 2013 Pearson Education, Inc. Basilic vein Ulnar vein Deep venous palmar arch Superficial venous palmar arch Digital veins Figure 19.29a Veins of the abdomen. Inferior vena cava Cystic vein Hepatic portal system Inferior phrenic veins Hepatic veins Hepatic portal vein Superior mesenteric vein Splenic vein Suprarenal veins Renal veins Inferior mesenteric vein Gonadal veins Lumbar veins R. ascending lumbar vein L. ascending lumbar vein Common iliac veins External iliac vein Internal iliac veins Schematic flowchart. © 2013 Pearson Education, Inc. Figure 19.29b Veins of the abdomen. Hepatic veins Inferior phrenic vein Inferior vena cava Right suprarenal vein Left suprarenal vein Renal veins Right gonadal vein External iliac vein Left ascending lumbar vein Lumbar veins Left gonadal vein Common iliac vein Internal iliac vein Tributaries of the inferior vena cava. Venous drainage of abdominal organs not drained by the hepatic portal vein. © 2013 Pearson Education, Inc. Figure 19.29c Veins of the abdomen. Hepatic veins Liver Hepatic portal vein Gastric veins Spleen Inferior vena cava Splenic vein Right gastroepiploic vein Inferior mesenteric vein Superior mesenteric vein Small intestine Large intestine Rectum The hepatic portal circulation. © 2013 Pearson Education, Inc. Figure 19.30a Veins of the right lower limb. Internal iliac vein Inferior vena cava Common iliac vein External iliac vein Femoral vein Great saphenous vein Femoral vein Popliteal vein Small saphenous vein Small saphenous vein Anterior tibial vein Fibular (peroneal) vein Fibular (peroneal) vein Posterior tibial vein Plantar veins Dorsalis pedis vein Dorsal venous arch Deep plantar arch Dorsal metatarsal veins Digital veins Anterior Posterior Schematic flowchart of the anterior and posterior veins © 2013 Pearson Education, Inc. Figure 19.30b Veins of the right lower limb. Common iliac vein Internal iliac vein External iliac vein Inguinal ligament Femoral vein Great saphenous vein (superficial) Popliteal vein Small saphenous vein Fibular vein Anterior tibial vein Dorsalis pedis vein Dorsal venous arch Dorsal metatarsal veins © 2013 Pearson Education, Inc. Anterior view Figure 19.30c Veins of the right lower limb. Great saphenous vein Popliteal vein Anterior tibial vein Fibular vein Small saphenous vein (superficial) Posterior tibial vein Plantar veins Deep plantar arch Digital veins © 2013 Pearson Education, Inc. Posterior view