An Introduction to Blood Vessels and Circulation

An Introduction to Blood Vessels and Circulation
Are classified by size and histological organization Are instrumental in overall cardiovascular regulation © 2015 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 © 2015 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 © 2015 Pearson Education, Inc.

21-1 Blood Vessels The Smallest Blood Vessels Capillaries
Have small diameter and thin walls Chemicals and gases diffuse across walls © 2015 Pearson Education, Inc.

21-1 Blood Vessels The Structure of Vessel Walls
Walls have three layers Tunica intima Tunica media Tunica externa © 2015 Pearson Education, Inc.

Tunica externa Tunica media Tunica intima Smooth muscle Lumen of vein
Figure 21-1 Comparisons of a Typical Artery and a Typical Vein (Part 1 of 2). Tunica externa Tunica media Tunica intima Smooth muscle Lumen of vein Internal elastic membrane External elastic membrane Lumen of artery Endothelium Elastic fiber ARTERY Artery and vein LM × 60

Tunica externa Tunica media Tunica intima Lumen of vein Smooth muscle
Figure 21-1 Comparisons of a Typical Artery and a Typical Vein (Part 2 of 2). Tunica externa Tunica media Tunica intima Lumen of vein Smooth muscle Lumen of artery Endothelium Artery and vein LM × 60 VEIN

21-1 Structure and Function of Arteries
Vasoconstriction and Vasodilation Affect: Afterload on heart (pressure against which the heart must work to eject blood during systole). Peripheral blood pressure Capillary blood flow © 2015 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 © 2015 Pearson Education, Inc.

Figure 21-2 Histological Structure of Blood Vessels.
Veins Arteries Large Vein Elastic Artery Tunica externa Internal elastic membrane Tunica intima Tunica media Endothelium Endothelium Tunica media Tunica intima Tunica externa Medium-sized Vein Muscular Artery Tunica externa Tunica externa Tunica media Tunica media Endothelium Endothelium Tunica intima Tunica intima Venule Arteriole Smooth muscle cells (tunica media) Tunica externa Endothelium Endothelium Basement membrane Fenestrated Capillary Capillaries Continuous Capillary Pores Endothelial cells Endothelial cells Basement membrane Basement membrane

21-1 Structure and Function of 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 © 2015 Pearson Education, Inc.

Figure 21-3 Capillary Structure.
Basement membrane Endothelial cell Nucleus Endosomes Endosomes Fenestrations, or pores Boundary between endothelial cells Boundary between endothelial cells Basement membrane Gap between adjacent cells Basement membrane a Continuous capillary b Fenestrated capillary c Sinusoid

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 © 2015 Pearson Education, Inc.

Figure 21-4a The Organization of a Capillary Bed.
Vein Collateral arteries Smooth muscle cells Venule Arteriole Thoroughfare channel Metarterioles Capillaries Section of precapillary sphincter Small venule Precapillary sphincters KEY Arteriovenous anastomosis Consistent blood flow Variable blood flow a A typical capillary bed. Solid arrows indicate consistent blood flow; dashed arrows indicate variable or pulsating blood flow.

Case Study – Blood Pressure
© 2015 Pearson Education, Inc. Case Study – Blood Pressure William, a 5'6", 210 lb., 64-year-old male business executive had a physical exam prior to his retirement from corporate work. His blood pressure was >180/115 on three separate days. Further examination showed normal to low plasma renin activity, elevated peripheral resistance (PR), cardiac output (CO) of 7.2 L/min (normal approx 5L/min), x-ray evidence of left ventricular hypertrophy, retinal hemorrhages, and mild polyuria. Recommended therapy was weight reduction to his ideal level, a low-salt diet (<2 gm/day sodium), prudent exercise, and a reduction in alcohol consumption (<3 oz whiskey/day). This change in lifestyle did little to change the condition. Medication was initiated in the form of an oral diuretic and progressed to a beta-blocker; eventually a vasodilator was included to reduce the blood pressure to <140/90.

Mean Arterial Pressure can be defined as the average arterial pressure during a single cardiac cycle.

© 2015 Pearson Education, Inc.
Pressure is generated as blood is pumped out of the left ventricle into the aorta and distributing arteries. Mean Aterial Pressure (MAP) MAP = CO x PR (SVP-Systemic Vascular Resistance) Cardiac Output (CO) * The amount of blood pumped by HEART per minute (ml/min) ( 5 L/m rest; up to 21 L/min) * CO=SV x HR (e.g 70 ml/beat x 71 BPM = 4,970 ml/min) SV: Stroke volume of blood pumped w/ each heart beat HR: Heart rate or number of times heart beats per minute * CO changes w/ stress, anxiety, drugs, heart disease or  body temp Peripheral Resistance (PR) * Opposition to flow through BLOOD VESSELS. It is an Index of friction or drag * Determined by: blood vessels diameter (the most significant regulator of blood flow) blood viscosity (doesn’t change much from moment to moment)  viscosity with anemia, hypoproteinemia  viscosity with polycythemia , dehydration blood vessel length (doesn’t change much from moment to moment) CVP – Central Venous Pressure Which is usually 0

Cardiovascular Regulation
© 2015 Pearson Education, Inc. Controlling Cardiac Output, Peripheral Resistance and, therefore, Blood Pressure Autoregulation Causes immediate, localized homeostatic adjustments Neural mechanisms Respond quickly to changes at specific sites Endocrine mechanisms Direct long-term changes Cardiovascular Regulation Controlling Cardiac Output, Peripheral Resistance and, therefore, Blood Pressure Autoregulation Causes immediate, localized homeostatic adjustments Neural mechanisms Respond quickly to changes at specific sites Endocrine mechanisms Direct long-term changes © 2015 Pearson Education, Inc.

Start Autoregulation HOMEOSTASIS
Autoregulation involves changes in the pattern of blood flow within capillary beds as precapillary sphincters open and close in response to chemical changes in the interstitial fluid. Factors that promote the dilation of blood vessels are called vasodilators. Local vasodilators such as lactic acid accelerate blood flow through their tissue of origin. HOMEOSTASIS RESTORED Local decrease in resistance and increase in blood flow HOMEOSTASIS Normal blood pressure and volume 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) • Increased tissue activity Start

Central Regulation Central regulation involves both
neural and endocrine mechanisms. Activation of the cardiovascular center involves both the cardioacceleratory center (which stimulates the heart) and the vasomotor center (which controls the degree of peripheral vasoconstriction). Neural mechanisms elevate cardiac output and reduce blood flow to nonessential or inactive tissues. The primary vasoconstrictor involved in neural regulation is norepinephrine (NE). Endocrine mechanisms involve long-term increases in blood volume and blood pressure. Stimulation of receptors sensitive to changes in systemic blood pressure or chemistry Short-term elevation of blood pressure by sympathetic stimulation of the heart and peripheral vasoconstriction Activation of cardiovascular center Neural mechanisms Stimulation of endocrine response Long-term increase in blood volume and blood pressure Endocrine mechanisms If autoregulation is ineffective HOMEOSTASIS RESTORED

© 2015 Pearson Education, Inc. 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) released by endothelium cells of blood vessels causes relaxation of smooth muscle High K+ or H+ concentrations Chemicals released by inflammation (histamine) Elevated local temperature 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) released by endothelium cells of blood vessels causes relaxation of smooth muscle High K+ or H+ concentrations Chemicals released by inflammation (histamine) Elevated local temperature

© 2015 Pearson Education, Inc. Autoregulation of Blood Flow within Tissues Adjusted by peripheral resistance while cardiac output stays the same Local vasoconstrictors Examples: endothelins (peptides that constrict blood vessels and raise blood pressure) Clotting factors released by damaged tissues Constrict precapillary sphincters Affect a single capillary bed Cardiovascular Regulation Autoregulation of Blood Flow within Tissues Adjusted by peripheral resistance while cardiac output stays the same Local vasoconstrictors Examples: endothelins (peptides that constrict blood vessels and raise blood pressure) Clotting factors released by damaged tissues Constrict precapillary sphincters Affect a single capillary bed

© 2015 Pearson Education, Inc. Neural Mechanisms Cardiovascular (CV) centers of the medulla oblongata Cardiac centers Cardioacceleratory center increases cardiac output Cardioinhibitory center reduces cardiac output Cardiovascular Regulation Neural Mechanisms Cardiovascular (CV) centers of the medulla oblongata Cardiac centers Cardioacceleratory center increases cardiac output Cardioinhibitory center reduces cardiac output

© 2015 Pearson Education, Inc. Vasomotor Center in Medulla Control of vasoconstriction Controlled by adrenergic nerves (NE) Stimulates smooth muscle contraction in arteriole walls Control of vasodilation Controlled by cholinergic nerves Relaxes smooth muscle Cardiovascular Regulation Vasomotor Center in Medulla Control of vasoconstriction Controlled by adrenergic nerves (NE) Stimulates smooth muscle contraction in arteriole walls Control of vasodilation Controlled by cholinergic nerves Relaxes smooth muscle

© 2015 Pearson Education, Inc. 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 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

© 2015 Pearson Education, Inc. Baroreceptor Reflexes Stretch receptors in walls of: Carotid sinuses (maintain blood flow to brain) Aortic sinuses (monitor start of systemic circuit) Right atrium (monitors end of systemic circuit) Cardiovascular Regulation Baroreceptor Reflexes Stretch receptors in walls of: Carotid sinuses (maintain blood flow to brain) Aortic sinuses (monitor start of systemic circuit) Right atrium (monitors end of systemic circuit)

Baroreceptor Reflexes of the Carotid and Aortic Sinuses (Part 1 of 2).
Cardioinhibitory center stimulated Cardioacceleratory center inhibited Decreased cardiac output Responses to Increased Baroreceptor Stimulation Vasomotor center inhibited Baroreceptors stimulated Vasodilation occurs HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Increasing blood pressure Blood pressure decreases Start HOMEOSTASIS Normal range of blood pressure

Baroreceptor Reflexes of the Carotid and Aortic Sinuses (Part 2 of 2).
HOMEOSTASIS Normal range of blood pressure Start HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Decreasing blood pressure Blood pressure increases Vasoconstriction occurs Baroreceptors inhibited Vasomotor center stimulated Increased cardiac output Responses to Decreased Baroreceptor Stimulation Cardioacceleratory center stimulated Cardioinhibitory center inhibited

© 2015 Pearson Education, Inc. Chemoreceptor Reflexes Peripheral chemoreceptors in carotid bodies and aortic bodies monitor blood Cardiovascular Regulation Chemoreceptor Reflexes Peripheral chemoreceptors in carotid bodies and aortic bodies monitor blood

© 2015 Pearson Education, Inc. Chemoreceptor Reflexes Changes in pH, O2, and CO2 concentrations Produced by coordinating cardiovascular and respiratory activities Cardiovascular Regulation Chemoreceptor Reflexes Changes in pH, O2, and CO2 concentrations Produced by coordinating cardiovascular and respiratory activities

The Chemoreceptor Reflexes.
Respiratory centers in the medulla oblongata stimulated Respiratory Response Respiratory rate increases Increasing CO2 levels, decreasing pH and O2 levels Effects on Cardiovascular Center Cardiovascular Responses Cardioacceleratory center stimulated Reflex Response Increased cardiac output and blood pressure Chemoreceptors stimulated Cardioinhibitory center inhibited Vasomotor center stimulated Vasoconstriction occurs Start HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Increased 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

© 2015 Pearson Education, Inc. 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 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

© 2015 Pearson Education, Inc. 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 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

© 2015 Pearson Education, Inc. Angiotensin II Responds to fall in renal blood pressure Stimulates: Aldosterone production ADH production Thirst Cardiac output and peripheral vasoconstriction Cardiovascular Regulation Angiotensin II Responds to fall in renal blood pressure Stimulates: Aldosterone (reabsorption of sodium in kidneys) production ADH production Thirst Cardiac output and peripheral vasoconstriction

© 2015 Pearson Education, Inc. Erythropoietin (EPO) Released at kidneys Responds to low blood pressure, low O2 content in blood Stimulates red blood cell production Cardiovascular Regulation Erythropoietin (EPO) Released at kidneys Responds to low blood pressure, low O2 content in blood Stimulates red blood cell production

The Hormonal Regulation of Blood Pressure and Blood Volume.
HOMEOSTASIS Normal blood pressure and volume HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Start Blood pressure and volume decrease Blood pressure and volume increase Decreasing blood pressure and volume Short-term Long-term Combined Short-Term and Long-Term Effects Sympathetic activation and release of adrenal hormones E and NE Increased blood pressure Increased blood volume Endocrine Response of Kidneys Increased cardiac output and peripheral vasoconstriction Renin release leads to angiotensin II activation Erythropoietin (EPO) is released Angiotensin II Effects Antidiuretic hormone released Aldosterone secreted Thirst stimulated Factors that compensate for decreased blood pressure and volume a Increased red blood cell formation

© 2015 Pearson Education, Inc. 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 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

The Hormonal Regulation of Blood Pressure and Blood Volume.
Responses to ANP and BNP Increased Na loss in urine + Increased water loss in urine Decreased thirst Combined Effects Natriuretic peptides released by the heart Inhibition of ADH, aldosterone, epinephrine, and norepinephrine release Decreased blood volume Peripheral vasodilation HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Increasing blood pressure and volume Decreasing blood pressure and volume HOMEOSTASIS Increasing blood pressure and volume Normal blood pressure and volume b Factors that compensate for increased blood pressure and volume

Case Study – Blood Pressure William, a 5'6", 210 lb., 64-year-old male business executive had a physical exam prior to his retirement from corporate work. His blood pressure was >180/115 on three separate days. Further examination showed normal to low plasma renin activity, elevated total peripheral resistance (TPR), cardiac output (CO) of 7.2 L/min (normal approx 5L/min), x-ray evidence of left ventricular hypertrophy, retinal hemorrhages, and mild polyuria (hypertension causes excessive kidney filtration). Recommended therapy was weight reduction to his ideal level, a low-salt diet (<2 gm/day sodium), prudent exercise, and a reduction in alcohol consumption (<3 oz whiskey/day). This change in lifestyle did little to change the condition. Medication was initiated in the form of an oral diuretic (excess water excretion and lower blood volume) and progressed to a beta-blocker (blocks receptors for epinephrine and norepinephrine which slows down your heart rate and reduce the force of heart contraction, also blocks kidneys from producing a angiotensin II, reducing the amount of angiotensin so blood vessels relax and widen, making it easier for blood to flow through; eventually a vasodilator was included to reduce the blood pressure to <140/90.

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Figure 21-5 The Function of Valves in the Venous System.
closed Valve opens superior to contracting muscle Valve closed Valve closes inferior to contracting muscle

21-2 Pressure and Resistance
Total Capillary Blood Flow Equals cardiac output Is determined by: Pressure (P) and resistance (R) in the cardiovascular system © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Measuring Pressure Blood pressure (BP) Arterial pressure (mm Hg) Capillary hydrostatic pressure (CHP) Pressure within the capillary beds Venous pressure Pressure in the venous system © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Figure 21-7 Factors Affecting Friction and Vascular Resistance.
Factors Affecting Vascular Resistance Friction and Vessel Length Resistance to flow = 1 Internal surface area = 1 Flow = 1 Resistance to flow = 2 Internal surface area = 2 Flow = 1 2 Friction and Vessel Diameter Greatest resistance near surfaces, slowest flow Least resistance at center greatest flow Vessel Length versus Vessel Diameter Diameter = 2 cm Resistance to flow = 1 Diameter = 1 cm Resistance to flow = 16 Turbulence Plaque deposit Turbulence

Table 21-1 Key Terms and Relationships Pertaining to Blood Circulation (Part 1 of 3).

Vessel diameter 3 2 Vessel diameter (cm) 1 Aorta a Elastic arteries
Figure 21-8a Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and Blood Velocity within the Systemic Circuit. 3 2 Vessel diameter (cm) 1 Elastic arteries Muscular arteries Arterioles Capillaries Venules Veins Venae cavae Aorta Vessel diameter a

Total cross-sectional area of vessels
Figure 21-8b Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and Blood Velocity within the Systemic Circuit. 5000 4000 Cross- sectional area (cm2) 3000 2000 1000 Elastic arteries Muscular arteries Arterioles Capillaries Venules Veins Venae cavae Aorta Total cross-sectional area of vessels b

Average blood pressure
Figure 21-8c Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and Blood Velocity within the Systemic Circuit. 120 100 80 Average blood pressure (mm Hg) 60 40 20 Elastic arteries Muscular arteries Arterioles Capillaries Venules Veins Venae cavae Aorta Average blood pressure c

Velocity of blood flow 35 28 Velocity of blood flow 21 (cm/sec) 14 7
Figure 21-8d Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and Blood Velocity within the Systemic Circuit. 35 28 Velocity of blood flow (cm/sec) 21 14 7 Elastic arteries Muscular arteries Arterioles Capillaries Venules Veins Venae cavae Aorta Velocity of blood flow d

Arterial Blood Pressure Pulse pressure Difference between systolic pressure and diastolic pressure Mean arterial pressure (MAP) MAP = diastolic pressure + 1/3 pulse pressure © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Figure 21-9 Pressures within the Systemic Circuit.
Systolic 120 Pulse pressure 100 Mean arterial pressure 80 Diastolic 60 mm Hg 40 20 Aorta Elastic arteries Muscular arteries Arterioles Capillaries Venules Medium- sized veins Large veins Venae cavae

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 © 2015 Pearson Education, Inc.

Diffusion Routes Water, ions, and small molecules such as glucose Diffuse between adjacent endothelial cells Or through fenestrated capillaries Some ions (Na+, K+, Ca2+, Cl−) Diffuse through channels in plasma membranes © 2015 Pearson Education, Inc.

Diffusion Routes Large, water-soluble compounds Pass through fenestrated capillaries Lipids and lipid-soluble materials such as O2 and CO2 Diffuse through endothelial plasma membranes Plasma proteins Cross endothelial lining in sinusoids © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Figure 21-10 Capillary Filtration.
hydrostatic pressure (CHP) Amino acid Blood protein Glucose Ions Interstitial fluid Small solutes Hydrogen bond Water molecule Endothelial cell 1 Endothelial cell 2

Interplay between Filtration and Reabsorption Ensures that plasma and interstitial fluid are in constant communication and mutual exchange Accelerates distribution of: Nutrients, hormones, and dissolved gases throughout tissues © 2015 Pearson Education, Inc.

Interplay between Filtration and Reabsorption Assists in the transport of: Insoluble lipids and tissue proteins that cannot enter bloodstream by crossing capillary walls Has a flushing action that carries bacterial toxins and other chemical stimuli to: Lymphatic tissues and organs responsible for providing immunity to disease © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Factors that Contribute to Net Hydrostatic Pressure Capillary hydrostatic pressure (CHP) Interstitial fluid hydrostatic pressure (IHP) Net capillary hydrostatic pressure tends to push water and solutes: Out of capillaries Into interstitial fluid © 2015 Pearson Education, Inc.

Net Capillary Colloid Osmotic Pressure Is the difference between: Blood colloid osmotic pressure (BCOP) and Interstitial fluid colloid osmotic pressure (ICOP) Pulls water and solutes: Into a capillary From interstitial fluid © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Figure 21-11 Forces Acting across Capillary Walls.
Return to circulation 3.6 L/day flows into lymphatic vessels Arteriole KEY Venule CHP (Capillary hydrostatic pressure) Filtration Reabsorption BOP (Blood osmotic pressure) No net fluid movement 24 L/day 20.4 L/day 35 mm Hg 25 mm Hg 25 mm Hg 25 mm Hg 18 mm Hg 25 mm Hg NFP (Net filtration pressure) NFP = +10 mm Hg NFP = 0 NFP = 7 mm Hg CHP > BCOP Fluid forced out of capillary CHP = BCOP No net movement of fluid BCOP > CHP Fluid moves into capillary

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 declines Fluid moves out of blood Builds up in peripheral tissues (edema) © 2015 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: Cardiac output Peripheral resistance Blood pressure © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Start Autoregulation HOMEOSTASIS
Figure Short-Term and Long-Term Cardiovascular Responses (Part 2 of 2). Autoregulation Autoregulation involves changes in the pattern of blood flow within capillary beds as precapillary sphincters open and close in response to chemical changes in the interstitial fluid. Factors that promote the dilation of blood vessels are called vasodilators. Local vasodilators such as lactic acid accelerate blood flow through their tissue of origin. HOMEOSTASIS RESTORED Local decrease in resistance and increase in blood flow HOMEOSTASIS Normal blood pressure and volume 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 Start

Figure 21-12 Short-Term and Long-Term Cardiovascular Responses (Part 1 of 2).
Central Regulation Central regulation involves both neural and endocrine mechanisms. Activation of the cardiovascular center involves both the cardioacceleratory center (which stimulates the heart) and the vasomotor center (which controls the degree of peripheral vasoconstriction). Neural mechanisms elevate cardiac output and reduce blood flow to nonessential or inactive tissues. The primary vasoconstrictor involved in neural regulation is norepinephrine (NE). Endocrine mechanisms involve long-term increases in blood volume and blood pressure. Stimulation of receptors sensitive to changes in systemic blood pressure or chemistry Short-term elevation of blood pressure by sympathetic stimulation of the heart and peripheral vasoconstriction Activation of cardiovascular center Neural mechanisms Stimulation of endocrine response Long-term increase in blood volume and blood pressure Endocrine mechanisms If autoregulation is ineffective HOMEOSTASIS RESTORED

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Neural Mechanisms Cardiovascular (CV) centers of the medulla oblongata Cardiac centers Cardioacceleratory center increases cardiac output Cardioinhibitory center reduces cardiac output © 2015 Pearson Education, Inc.

Vasomotor Center Control of vasoconstriction Controlled by adrenergic nerves (NE) Stimulates smooth muscle contraction in arteriole walls Control of vasodilation Controlled by cholinergic nerves (NO) Relaxes smooth muscle Vasomotor Tone Produced by constant action of sympathetic vasoconstrictor nerves © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Baroreceptor Reflexes Stretch receptors in walls of: Carotid sinuses (maintain blood flow to brain) Aortic sinuses (monitor start of systemic circuit) Right atrium (monitors end of systemic circuit) © 2015 Pearson Education, Inc.

Baroreceptor Reflexes When blood pressure rises, CV centers: Decrease cardiac output Cause peripheral vasodilation When blood pressure falls, CV centers: Increase cardiac output Cause peripheral vasoconstriction © 2015 Pearson Education, Inc.

Responses to Increased Baroreceptor Stimulation HOMEOSTASIS DISTURBED
Figure Baroreceptor Reflexes of the Carotid and Aortic Sinuses (Part 1 of 2). Cardioinhibitory center stimulated Cardioacceleratory center inhibited Decreased cardiac output Responses to Increased Baroreceptor Stimulation Vasomotor center inhibited Baroreceptors stimulated Vasodilation occurs HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Increasing blood pressure Blood pressure decreases Start HOMEOSTASIS Normal range of blood pressure

HOMEOSTASIS DISTURBED Responses to Decreased Baroreceptor Stimulation
Figure Baroreceptor Reflexes of the Carotid and Aortic Sinuses (Part 2 of 2). HOMEOSTASIS Normal range of blood pressure Start HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Decreasing blood pressure Blood pressure increases Vasoconstriction occurs Baroreceptors inhibited Vasomotor center stimulated Increased cardiac output Responses to Decreased Baroreceptor Stimulation Cardioacceleratory center stimulated Cardioinhibitory center inhibited

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 © 2015 Pearson Education, Inc.

Figure 21-14 The Chemoreceptor Reflexes.
Respiratory centers in the medulla oblongata stimulated Respiratory Response Respiratory rate increases Increasing CO2 levels, decreasing pH and O2 levels Effects on Cardiovascular Center Cardiovascular Responses Cardioacceleratory center stimulated Reflex Response Increased cardiac output and blood pressure Chemoreceptors stimulated Cardioinhibitory center inhibited Vasomotor center stimulated Vasoconstriction occurs Start HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Increased 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

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Factors that compensate for decreased blood pressure and volume
Figure 21-15a The Hormonal Regulation of Blood Pressure and Blood Volume. HOMEOSTASIS Normal blood pressure and volume HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Start Blood pressure and volume decrease Blood pressure and volume increase Decreasing blood pressure and volume Short-term Long-term Combined Short-Term and Long-Term Effects Sympathetic activation and release of adrenal hormones E and NE Increased blood pressure Increased blood volume Endocrine Response of Kidneys Increased cardiac output and peripheral vasoconstriction Renin release leads to angiotensin II activation Erythropoietin (EPO) is released Angiotensin II Effects Antidiuretic hormone released Aldosterone secreted Thirst stimulated Factors that compensate for decreased blood pressure and volume a Increased red blood cell formation

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 © 2015 Pearson Education, Inc.

+ Factors that compensate for increased blood pressure and volume
Figure 21-15b The Hormonal Regulation of Blood Pressure and Blood Volume. Responses to ANP and BNP Increased Na loss in urine + Increased water loss in urine Decreased thirst Combined Effects Natriuretic peptides released by the heart Inhibition of ADH, aldosterone, epinephrine, and norepinephrine release Decreased blood volume Peripheral vasodilation HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Increasing blood pressure and volume Decreasing blood pressure and volume HOMEOSTASIS Increasing blood pressure and volume Normal blood pressure and volume b Factors that compensate for increased 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 © 2015 Pearson Education, Inc.

The Cardiovascular Response to Exercise Light Exercise Extensive vasodilation occurs, increasing circulation Venous return increases with muscle contractions Cardiac output rises Venous return (Frank–Starling principle) Atrial stretching © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Table 21-2 Changes in Blood Distribution during Exercise.

Table 21-3 Effects of Training on Cardiovascular Performance.

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Figure 21-16 Cardiovascular Responses to Blood Loss.
HOMEOSTASIS Normal blood pressure and volume HOMEOSTASIS RESTORED HOMEOSTASIS DISTURBED Blood pressure and volume increase Extensive bleeding decreases blood pressure and volume Decreasing blood pressure and volume Responses coordinated by the endocrine system Increase in blood volume Responses directed by the nervous system Long-Term Hormonal Response Cardiovascular Responses ADH, angiotensin II, aldosterone, and EPO released Peripheral vasoconstriction; mobilization of venous reserve Increased cardiac output Stimulation of baroreceptors and chemoreceptors Pain, stress, anxiety, fear Higher Centers Stimulation of cardiovascular center General sympathetic activation

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 © 2015 Pearson Education, Inc.

21-5 Pulmonary and Systemic Patterns
Three General Functional Patterns Peripheral artery and vein distribution is the same on right and left, except near the heart The same vessel may have different names in different locations Tissues and organs usually have multiple arteries and veins Vessels may be interconnected with anastomoses © 2015 Pearson Education, Inc.

Figure 21-17 A Schematic Overview of the Pattern of Circulation (Part 1 of 2).
Brain Upper limbs Pulmonary circuit (veins) Lungs LA Systemic circuit (arteries) Left ventricle Kidneys Spleen Digestive organs Liver Gonads Lower limbs

Figure 21-17 A Schematic Overview of the Pattern of Circulation (Part 2 of 2).
Brain Upper limbs Pulmonary circuit (arteries) Lungs RA Right ventricle Systemic circuit (veins) Kidneys Digestive organs Liver Gonads Lower limbs

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 © 2015 Pearson Education, Inc.

Pulmonary Vessels Pulmonary arteries Carry deoxygenated blood Pulmonary trunk Branches to left and right pulmonary arteries Branch into pulmonary arterioles Pulmonary arterioles Branch into capillary networks that surround alveoli © 2015 Pearson Education, Inc.

Pulmonary Vessels Pulmonary veins Carry oxygenated blood Capillary networks around alveoli Join to form venules Venules Join to form four pulmonary veins Empty into left atrium © 2015 Pearson Education, Inc.

Figure 21-18 The Pulmonary Circuit (Part 1 of 2).
Ascending aorta Superior vena cava Right lung Right pulmonary arteries Right pulmonary veins Inferior vena cava Descending aorta

Figure 21-18 The Pulmonary Circuit (Part 2 of 2).
Aortic arch Pulmonary trunk Left lung Left pulmonary arteries Left pulmonary veins Alveolus Capillary O2 CO2 Inferior vena cava Descending aorta

21-7 The Systemic Circuit The Systemic Circuit
Contains 84 percent of blood volume Supplies entire body Except for pulmonary circuit © 2015 Pearson Education, Inc.

21-7 The Systemic Circuit Systemic Arteries
Blood moves from left ventricle Into ascending aorta Coronary arteries Branch from aortic sinus © 2015 Pearson Education, Inc.

Figure 21-19 An Overview of the Major Systemic Arteries (Part 1 of 2).
Vertebral Right subclavian Right common carotid Left common carotid Brachiocephalic trunk Left subclavian Aortic arch Axillary Pulmonary trunk Ascending aorta Descending aorta Celiac trunk Diaphragm Superior mesenteric Brachial Renal Gonadal Inferior mesenteric Radial Common iliac Internal iliac Ulnar External iliac Palmar arches Deep femoral Femoral

Figure 21-19 An Overview of the Major Systemic Arteries (Part 2 of 2).
Femoral Descending genicular Popliteal Posterior tibial Anterior tibial Fibular Dorsalis pedis Plantar arch

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 © 2015 Pearson Education, Inc.

Figure 21-20 Arteries of the Chest and Upper Limb.
Right thyrocervical trunk Right vertebral Supplies muscles, skin, tissues of neck, thyroid gland, shoulders, and upper back (right side) Supplies spinal cord, cervical vertebrae (right side); fuses with left vertebral, forming basilar artery after entering cranium through foramen magnum Right common carotid Left common carotid Left subclavian (see Figure 21–21) Right subclavian Brachiocephalic trunk Right thyrocervical trunk Right common carotid Right internal thoracic Right vertebral Left common carotid Supplies skin and muscles of chest and abdomen, mammary gland (right side), pericardium Aortic arch Thoracoacromial Right axillary Left subclavian Supplies muscles of the right pectoral region and axilla Lateral thoracic Ascending aorta Anterior humeral circumflex Posterior humeral circumflex Thoracic aorta LEFT VENTRICLE Subscapular Deep brachial Intercostals Thoracic aorta (see Figure 21–23) Right brachial Supplies structures of the arm Ulnar collateral arteries Abdominal aorta Right radial Right ulnar Anterior ulnar recurrent Supplies forearm, radial side Supplies forearm, ulnar side Posterior ulnar recurrent Anterior crural interosseous The radial and ulnar arteries are connected by anastomoses of palmar arches that supply digital arteries Deep palmar arch Superficial palmar arch Digital arteries

21-7 The Systemic Circuit Branches of the Aortic Arch
Deliver blood to head, neck, shoulders, and upper limbs Brachiocephalic trunk Left common carotid artery Left subclavian artery © 2015 Pearson Education, Inc.

21-7 The Systemic Circuit The Subclavian Arteries
Leaving the thoracic cavity: Become axillary artery in arm And brachial artery distally © 2015 Pearson Education, Inc.

Figure 21-20 Arteries of the Chest and Upper Limb (Part 1 of 2).

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 © 2015 Pearson Education, Inc.

Figure 21-20 Arteries of the Chest and Upper Limb (Part 2 of 2).

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 Ophthalmic artery Anterior cerebral artery Middle cerebral artery © 2015 Pearson Education, Inc.

Figure 21-21 Arteries of the Neck and Head (Part 1 of 2).
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 Clavicle Internal thoracic First rib Second rib

Figure 21-21 Arteries of the Neck and Head (Part 2 of 2).
Branches of the External Carotid Superficial temporal Maxillary Occipital Facial Lingual External carotid Common carotid Brachiocephalic trunk Clavicle First rib

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 © 2015 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 © 2015 Pearson Education, Inc.

Figure 21-22a Arteries of the Brain.
Cerebral Arterial Circle Anterior cerebral Anterior communicating Ophthalmic Anterior cerebral Internal carotid (cut) Posterior communicating Middle cerebral Posterior cerebral Pituitary gland Basilar Posterior cerebral Vertebral Cerebellar a Inferior surface

Figure 21-22b Arteries of the Brain.
Middle cerebral Anterior cerebral Posterior cerebral Ophthalmic Cerebral arterial circle Basilar Vertebral Internal carotid b Lateral view

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 © 2015 Pearson Education, Inc.

Figure 21-23a Major Arteries of the Trunk (Part 1 of 4).
Aortic arch Internal thoracic Thoracic aorta Somatic Branches of the Thoracic Aorta Intercostal arteries Superior phrenic Inferior phrenic a A diagrammatic view, with most of the thoracic and abdominal organs removed

Visceral Branches of the Thoracic Aorta Bronchial arteries Esophageal arteries Mediastinal artery Pericardial artery a A diagrammatic view, with most of the thoracic and abdominal organs removed

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 © 2015 Pearson Education, Inc.

Diaphragm Adrenal Renal Gonadal Lumbar Terminal segment of the aorta Common iliac Median sacral a A diagrammatic view, with most of the thoracic and abdominal organs removed

Celiac Trunk Left gastric Splenic Common hepatic Superior mesenteric Abdominal aorta Inferior mesenteric a A diagrammatic view, with most of the thoracic and abdominal organs removed

Hepatic artery proper (liver)
Figure Arteries Supplying the Abdominopelvic Organs (Part 1 of 2). Branches of the Common Hepatic Artery Hepatic artery proper (liver) Gastroduodenal (stomach and duodenum) Liver Cystic (gallbladder) Right gastric (stomach) Right gastroepiploic (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

Pancreatic (pancreas)
Figure Arteries Supplying the Abdominopelvic Organs (Part 2 of 2). The Celiac Trunk Common hepatic Left gastric Splenic Spleen Stomach Branches of the Splenic Artery Left gastroepiploic (stomach) Pancreatic (pancreas) Pancreas Inferior Mesenteric Artery Left colic (colon) Sigmoid (colon) Rectal (rectum) Small intestine Sigmoid colon Rectum

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 © 2015 Pearson Education, Inc.

Figure 21-23b Major Arteries of the Trunk (Part 2 of 2).
Right common iliac Left common iliac Pelvis and right lower limb Pelvis and left lower limb Right external Iliac (see Figure 21–25) Right internal iliac Left internal iliac Left external iliac Pelvic muscles, skin, urinary and reproductive organs, perineum, gluteal, region, and medial thigh Superior gluteal Internal pudendal Hip muscles and joint Lateral rotators of hip; rectum, anus, perineal muscles, external genitalia Obturator Ilium, hip and thigh muscles, hip joint and femoral head Lateral sacral Skin and muscles of sacrum b A flowchart showing major arteries of the trunk

Figure 21-25a Arteries of the Lower Limb (Part 1 of 2).
Common iliac External iliac Internal iliac Superior gluteal Inguinal ligament Lateral sacral Internal pudendal Obturator Deep femoral Medial femoral circumflex Lateral femoral circumflex Femoral Descending genicular a Anterior view

Figure 21-25a Arteries of the Lower Limb (Part 2 of 2).
Popliteal Anterior tibial Posterior tibial Fibular Dorsalis pedis Medial plantar Lateral plantar Dorsal arch Plantar arch a Anterior view

Figure 21-25b Arteries of the Lower Limb (Part 1 of 2).
Superior gluteal Right external iliac Internal pudendal Femoral Obturator Deep femoral Lateral femoral circumflex Femoral Medial femoral circumflex Descending genicular b Posterior view

Figure 21-25b Arteries of the Lower Limb (Part 2 of 2).
Popliteal Anterior tibial Posterior tibial Fibular Posterior tibial b Posterior view

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 © 2015 Pearson Education, Inc.

Figure 21-26 An Overview of the Major Systemic Veins (Part 1 of 2).
KEY Superficial veins Deep veins Vertebral External jugular Internal jugular Subclavian Axillary Brachiocephalic Cephalic Superior vena cava Brachial Intercostal veins Basilic Inferior vena cava Hepatic veins Renal Median cubital Gonadal Radial Lumbar veins Median antebrachial Left and right common iliac Ulnar External iliac Palmar venous arches Internal iliac Digital veins Deep femoral Femoral

Figure 21-26 An Overview of the Major Systemic Veins (Part 2 of 2).
Great saphenous Femoral Popliteal Posterior tibial Small saphenous Anterior tibial Fibular KEY Superficial veins Plantar venous arch Deep veins Dorsal venous arch

21-7 The Systemic Circuit The Superior Vena Cava (SVC)
Receives blood from the tissues and organs of: Head Neck Chest Shoulders Upper limbs © 2015 Pearson Education, Inc.

Figure 21-27c Major Veins of the Head, Neck, and Brain.
Superior sagittal sinus Superficial cerebral veins Temporal Inferior sagittal sinus Deep cerebral Great cerebral Cavernous sinus Straight sinus Maxillary Petrosal sinuses Right transverse sinus Occipital sinus Facial Sigmoid sinus Occipital Vertebral External jugular Internal jugular Right subclavian Clavicle Right brachiocephalic Axillary Left brachiocephalic Superior vena cava First rib Internal thoracic c 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 © 2015 Pearson Education, Inc.

Figure 21-27b Major Veins of the Head, Neck, and Brain.
Inferior sagittal sinus Superior sagittal sinus Great cerebral vein Straight sinus Occipital sinus Cavernous sinus Petrosal sinuses Right transverse sinus Internal jugular Vertebral vein Right sigmoid sinus b A lateral view of the brain showing the venous distribution.

21-7 The Systemic Circuit Cerebral Veins Vertebral 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 © 2015 Pearson Education, Inc.

Figure 21-27a 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 a An inferior view of the brain, showing the venous distribution. For the relationship of these veins to meningeal layers, see Figure 14–3, p. 466.

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 © 2015 Pearson Education, Inc.

Figure 21-27c Major Veins of the Head, Neck, and Brain.
Superior sagittal sinus Superficial cerebral veins Temporal Inferior sagittal sinus Deep cerebral Great cerebral Cavernous sinus Straight sinus Maxillary Petrosal sinuses Right transverse sinus Occipital sinus Facial Sigmoid sinus Occipital Vertebral External jugular Internal jugular Right subclavian Clavicle Right brachiocephalic Axillary Left brachiocephalic Superior vena cava First rib Internal thoracic c 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 © 2015 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 © 2015 Pearson Education, Inc.

Median cubital Cephalic Superficial veins Anterior crural Deep veins
Figure The Venous Drainage of the Abdomen and Chest (Part 3 of 3). Median cubital KEY Cephalic Superficial veins Anterior crural interosseous Deep veins Radial Basilic Median antebrachial Ulnar Palmar venous arches Digital veins © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Vertebral Internal jugular External jugular Subclavian
Figure The Venous Drainage of the Abdomen and Chest (Part 2 of 3). 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 Medial sacral © 2015 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) © 2015 Pearson Education, Inc.

21-7 The Systemic Circuit Tributaries of the Superior Vena Cava
Azygos vein and hemiazygos vein, which receive blood from: Intercostal veins Esophageal veins Veins of other mediastinal structures © 2015 Pearson Education, Inc.

Figure The Venous Drainage of the Abdomen and Chest (Part 1 of 3). Superior vena cava Mediastinal veins Esophageal veins Azygos Internal thoracic Hepatic veins Renal veins Gonadal veins Lumbar veins Common iliac Internal iliac External iliac KEY Superficial veins Deep veins © 2015 Pearson Education, Inc.

Right brachiocephalic Left brachiocephalic
Figure Flowchart of Circulation to the Superior and Inferior Venae Cavae (Part 1 of 2). Right external jugular Right vertebral Right internal jugular Left internal jugular Left vertebral Left external jugular Collects blood from neck, face, salivary glands, scalp Collects blood from cranium, spinal cord, vertebrae Collects blood from cranium, face, and neck Right brachiocephalic Left brachiocephalic Through highest intercostal vein KEY Right subclavian Right internal thoracic Mediastinal veins Superior vena cava Left internal thoracic Left subclavian Superficial veins Deep veins Collects blood from structures of anterior thoracic wall Collect blood from the mediastinum RIGHT ATRIUM Right axillary Left axillary Right brachial Right cephalic Right basilic Azygos Hemiazygos Collects blood from veins of the left upper limb Collects blood from forearm, wrist, and hand Collects blood from lateral surface of upper limb Collects blood from medial surface of upper limb Right intercostal veins Esophageal veins Left intercostal veins Collect blood from vertebrae and body wall Collect blood from the esophagus Collect blood from vertebrae and body wall Interconnected by median cubital vein and median antebrachial network Right radial Right ulnar Radial side of forearm Ulnar side of forearm Inferior vena cava Venous network of wrist and hand

21-7 The Systemic Circuit The Inferior Vena Cava (IVC)
Collects blood from organs inferior to the diaphragm © 2015 Pearson Education, Inc.

spinal cord and body wall Collect blood from the kidneys
Figure Flowchart of Circulation to the Superior and Inferior Venae Cavae (Part 2 of 2). Inferior vena cava KEY Hepatic veins Phrenic veins Superficial veins Collect blood from the liver Collect blood from the diaphragm Deep veins Gonadal veins Adrenal veins Collect blood from the gonads Collect blood from the adrenal glands Lumbar veins Renal veins Collect blood from the spinal cord and body wall Collect blood from the kidneys Right common iliac Left common iliac Right external Iliac (see Figure 21–30) Right internal iliac Left internal iliac Left external iliac Gluteal veins Internal pudendal vein Obturator vein Lateral sacral vein Collects blood from the left gluteal, internal pudendal, obturator, and lateral sacral veins Collect blood from the pelvic muscles, skin, and urinary and reproductive organs of the right side of the pelvis Collects blood from veins of the right lower limb Collects blood from veins of the left lower limb

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 © 2015 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 Great saphenous vein (drains into femoral vein) Small saphenous vein (drains into popliteal vein) © 2015 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 © 2015 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 © 2015 Pearson Education, Inc.

Figure 21-30a Venous Drainage from the Lower Limb.
Common iliac Internal iliac Superior gluteal External iliac Inferior gluteal Lateral sacral Internal pudendal Obturator Femoral circumflex Femoral Deep femoral Femoral Collects blood from the thigh Great saphenous Great saphenous Collects blood from the superficial veins of the lower limb Small saphenous Collects blood from superficial veins of the leg and foot Popliteal Small saphenous Posterior tibial Fibular Anterior tibial Fibular The dorsal and plantar venous arches collect blood from the foot and toes Dorsal venous arch KEY Superficial veins Plantar venous arch Deep veins Digital a Anterior view

Figure 21-30b Venous Drainage from the Lower Limb.
Common iliac External iliac Superior gluteal Internal pudendal Inferior gluteal Obturator Femoral Femoral circumflex Deep femoral Deep femoral Collects blood from the thigh Femoral Great saphenous Collects blood from the superficial veins of the lower limb Small saphenous Collects blood from superficial veins of the leg and foot Popliteal Small saphenous Anterior tibial Posterior tibial Anterior tibial Fibular The dorsal and plantar venous arches collect blood from the foot and toes Dorsal venous arch KEY Superficial veins Plantar venous arch Deep veins Digital b Posterior view

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 © 2015 Pearson Education, Inc.

21-7 The Systemic Circuit Tributaries of the Hepatic Portal Vein
Inferior mesenteric vein Drains part of large intestine Splenic vein Drains spleen, part of stomach, and pancreas Superior mesenteric vein Drains part of stomach, small intestine, and part of large intestine Left and right gastric veins Drain part of stomach Cystic vein Drains gallbladder © 2015 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 © 2015 Pearson Education, Inc.

Figure 21-31 The Hepatic Portal System (Part 1 of 2).
Inferior vena cava Hepatic Liver Cystic Hepatic portal Superior Mesenteric Vein and Its Tributaries Pancreas Pancreaticoduodenal Middle colic (from transverse colon) Right colic (ascending colon) Ileocolic (Ileum and ascending colon) Intestinal (small intestine)

Figure 21-31 The Hepatic Portal System (Part 2 of 2).
Left gastric Right gastric Stomach Splenic Vein and Its Tributaries Left gastroepiploic (stomach) Spleen Right gastroepiploic (stomach) Pancreatic Pancreas Descending colon Inferior Mesenteric Vein and Its Tributaries Left colic (descending colon) Sigmoid (sigmoid colon) Superior rectal (rectum)

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

Figure 21-32a Fetal Circulation.
Aorta Foramen ovale (open) Ductuc arteriosis (open) Pulmonary trunk Liver Umbilical vein Inferior vena cava Ductus venosus Placenta Umbilical arteries Umbilical cord a Blood flow to and from the placenta in full-term fetus (before birth)

Figure 21-32b Fetal Circulation.
Ductus arteriosus (closed) Pulmonary trunk Left atrium Foramen ovale (closed) Right atrium Left ventricle Inferior vena cava Right ventricle b Blood flow through the neonatal (newborn) heart after delivery

Figure 21-33 Congenital Heart Problems (Part 6 of 6).
Normal Heart Structure Most congenital heart problems result from abnormal formation of the heart or problems with the connections between the heart and the great vessels.

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 © 2015 Pearson Education, Inc.

Patent Foramen Ovale and Patent Ductus Arteriosus 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 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.” Patent foramen ovale

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” © 2015 Pearson Education, Inc.

Tetralogy of Fallot Patent ductus arteriosus The tetralogy of Fallot (fa-LŌ) is a complex group of heart and circulatory defects that affect 0.10% 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 ventricle is enlarged and both ventricles thicken in response to the increased workload. Pulmonary stenosis Ventricular septal defect Enlarged right ventricle

Tetralogy of Fallot Complex group of heart and circulatory defects that affect percent of newborn infants Pulmonary trunk is abnormally narrow (pulmonary stenosis) Interventricular septum is incomplete Aorta originates where interventricular septum normally ends Right ventricle is enlarged and both ventricles thicken in response to increased workload © 2015 Pearson Education, Inc.

Ventricular Septal Defect A ventricular septal defect is an abnormal opening in the wall (septum) between the left and right ventricles. It affects 0.12% 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. Ventricular septal defect Interventricular septum

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 © 2015 Pearson Education, Inc.

Atrioventricular Septal Defect In an atrioventricular 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. Atrial defect Ventricular defect

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 © 2015 Pearson Education, Inc.

Transposition of the Great Vessels Patent ductus arteriosus In the transposition of the 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% of newborn infants. Aorta Pulmonary trunk

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 © 2015 Pearson Education, Inc.

21-9 Effects of Aging and the Cardiovascular System
Cardiovascular Capabilities Decline with Age Age-related changes occur in: Blood Heart Blood vessels © 2015 Pearson Education, Inc.

Five Age-Related Changes in the Heart Reduced maximum cardiac output Changes in nodal and conducting cells Reduced elasticity of cardiac (fibrous) skeleton Progressive atherosclerosis Replacement of damaged cardiac muscle cells by scar tissue © 2015 Pearson Education, Inc.

Three Age-Related Changes in Blood Vessels Arteries become less elastic Pressure change can cause aneurysm Calcium deposits on vessel walls Can cause stroke or infarction Thrombi can form At atherosclerotic plaques © 2015 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 © 2015 Pearson Education, Inc.

Figure diagrams the functional relationships between the cardiovascular system and the other body systems we have studied so far. SYSTEM INTEGRATOR Body System Cardivascular System Cardivascular System Body System Stimulation of mast cells produces localized changes in blood flow and capillary permeability Delivers immune system cells to injury sites; clotting response seals breaks in skin surface; carries away toxins from sites of infection; provides heat Integumentary Integumentary Page 174 Provides calcium needed for normal cardiac muscle contraction; protects blood cells developing in red bone marrow Transports calcium and phosphate for bone deposition; delivers EPO to red bone marrow, parathyroid hormone, and calcitonin to osteoblasts and osteoclasts Skeletal Skeletal Page 285 Skeletal muscle contractions assist in moving blood through veins; protects superficial blood vessels, especially in neck and limbs Delivers oxygen and nutrients, removes carbon dioxide, lactic acid, and heat during skeletal muscle activity Muscular Page 380 Controls patterns of circulation in peripheral tissues; modifies heart rate and regulates blood pressure; releases ADH Endothelial cells maintain blood– brain barrier; helps generate CSF Nervous Nervous Page 558 Erythropoietin regulates production of RBCs; several hormones elevate blood pressure; epinephrine stimulates cardiac muscle, elevating heart rate and contractile force Distributes hormones throughout the body; heart secretes ANP and BNP Endocrine Endocrine Page 647 The CARDIOVASCULAR System 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 824 Respiratory 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. Page 874 Digestive Page 929 Urinary Page 1010 Reproductive Page 1090

An Introduction to Blood Vessels and Circulation

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An Introduction to Blood Vessels and Circulation

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