blood vessels and circulation - dr. daniels websitejdaniels.huntingdon.edu/315/biol315 chapter...
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Blood Vessels and Circulation
Chapter 21
Five General Classes of Blood Vessels
• Arteries, which carry blood away from the heart
• Aterioles, the smallest arterial branches, that communicate with
• Capillaries, where diffusion (exchange) between blood and interstitial fluids occurs
• Venules, which carry blood from the capillary beds
• Veins, larger vessels that return blood to the heart
Anatomy of Blood Vessels• The walls of arteries and veins contain 3
distinct layers– The tunica intima, or tunica interna, consists of the
innermost endothelial layer and an underlying layer of connective tissuey
– The tunica media, contains concentric sheets of smooth muscle in a framework of loose connective tissues, commonly the thickest layer in arteries
– Tunica externa, or tunica adventitia, is the outermost layer and forms a connective tissue sheath around the vessel, that stabilizes and anchors the blood vessel
Differences between Arteries and Veins
• In general, the walls of arteries are thicker than those of veins, principally due to the thickness of the smooth muscle and elastic fibers in the tunica media
• When not opposed by blood pressure, the walls of pp y parteries constrict the lumen to a narrow diameter. Veins, on the other hand, tend to collapse and appear flattened in cross section
• The endothelial lining of an artery folds when an artery contracts, veins do not form folds
Arteries
• The contractile nature of the arterial wall gives arteries the ability to actively change diameter
• These changes in diameter are primarily under the control of the sympathetic division of the autonomic y pnervous system
• Vasoconstriction is the process by which the smooth muscle in arteries contract when stimulated and the diameter of the blood vessel decreases
• Vasodilation increases the diameter of the lumen and results from relaxation of the smooth muscle layer
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Arteries• Vasoconstriction and vasodilation affect
– The afterload of the heart
– Peripheral blood pressure
– & capillary bloodflow
• Arteries are classified, based on size, as either; elasticArteries are classified, based on size, as either; elastic (aka conducting), up to 2.5cm in diameter, or muscular (aka distribution or medium sized arteries) with a diameter of 0.5 to 4.0 mm
• Small arteries (generally with an internal diameter of 30 µm or less) are called arterioles
• See fig 21-2 on p711
• Structurally capillaries are an endothelial tube inside a basal lamina
• Capillaries are the only blood vessels permitting exchange between blood and surrounding tissues
Capillaries
• Because of this capillaries:– Surround muscle fibers
– Radiate through connective tissue
– & weave throughout all active tissues
• There are two major types of capillaries– Continuous capillaries with a complete endothelial
lining
– Fenestrated capillaries which contain pores spanning the endothelial lining
Capillaries
the endothelial lining• These pores (fenestrations) allow for much more rapid
movement of water and solutes between blood plasma and the interstitial fluids
• Sinusoids are a type of fenestrated capillary with flattened and irregular gaps between endothelial cells permitting a free exchange of water and solutes as large as plasma proteins
Figure 21-4 Capillary Structure
Basementmembrane
Nucleus
Endothelial cell
Endosomes
Boundarybetween
endothelialcells
Fenestrations,or pores
Boundarybetween
endothelialcells
Basementmembrane
Endosomes
Basementmembrane
Gap betweenadjacent cells
SinusoidFenestrated capillaryContinuous capillary
• Capillary beds are an interconnected network of vessels consisting of– The collateral arteries feeding an arteriole
M t t i l ( bl f t ti )
Capillary Beds
– Metarterioles (capable of contraction)
– Capillaries
– Arteriovenous anastomoses (joining of artery & vein)
– Venules
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• Each capillary bed – connects one arteriole to one venule
– & contains precapillary sphincters that regulates blood flow through the bed
Capillary Beds
blood flow through the bed
Veins
• Veins collect blood from all tissues and organs and return it to the heart
• Veins are also classified according to size V l ll t f ill b d– Venules - collect from capillary beds
– Medium-sized veins
– Large veins
• Venules and medium-sized veins contain valves which prevent the backflow of blood
Figure 21-6 The Function of Valves in the Venous System
Valve closed
Valve opens abovecontracting muscle
Valve closed
Valve closes belowcontracting muscle
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The Distribution of Blood
• Our blood volume is unevenly distributed among arteries, veins, and capillaries
• The heart, arteries, and capillaries normally contain about 30-35% of the blood volumeTh i h• The venous system contains the rest
• Veins, with their thinner walls, are much more distensible than arteries, as a result veins act as reservoir for blood volume and are termed capacitance vessels (arteries, with their contractile muscular walls are considered a reserve of pressure)
Figure 21-7 The Distribution of Blood in the Cardiovascular System
Large venousnetworks (liver,
bone marrow, skin)21%
Large veins18%
Venules andmedium-sized veins
25%
Cardiovascular Physiology
Cardiovascular Physiology
• The goal of cardiovascular regulation is the maintenance of adequate blood flow through the capillary beds in peripheral tissues and organs
• Under normal circumstances, this means that blood flow is equal to cardiac output
• When cardiac output increases, so does blood flow through the capillary beds…and vice versa
• Factors affecting blood flow and cardiac output fall under the broad topic: cardiovascular physiology
Blood flow
• Blood flow is determined by the interplay between pressure (P) and resistance (R) in the cardiovascular network.
• In order for blood to flow the heart must generate sufficient pressure to overcome the peripheral resistance in the pulmonary and systemic circuits
• As pressure (P) increases flow increases and as resistance (R) decreases flow increases
Blood flow
• Absolute pressure (the size of the number) is less important than the pressure gradient – the difference in pressure from one end of the vessel to the other.
• In other words, blood will flow as long as the gpressure is greater at one end of the vessel versus the other.
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Cardiovascular Physiology
• In order to understand cardiovascular physiology we must understand circulatory pressure and resistance, as well as the mechanisms of capillary exchange thatmechanisms of capillary exchange that ultimately provide part of the feedback that regulates pressure and resistance.
Circulatory Pressure
• Circulatory pressure can be divided into three components
• Blood pressure (BP), really arterial pressure, around 100mm Hg at aorta to 35mm ataround 100mm Hg at aorta to 35mm at capillary bed
• Capillary hydrostatic pressure, pressure within the capillary beds 35-18 mm Hg
• Venous pressure around 18 mm Hg
• Resistance of the cardiovascular system opposes the movement of blood
• For blood to flow, the circulatory pressure must t t l i h l i t th
Resistance (R)
overcome total peripheral resistance; the resistance of the entire cardiovascular system
Peripheral Resistance
• Peripheral resistance has three major components– Vascular resistance: the resistance of the blood
vessels is the largest component of peripheral resistance, it is dependent upon the length and diameter of the blood vessels
– Viscosity is resistance to flow caused by blood components, blood viscosity is generally stable excepting specific disorders
– Turbulence seldom occurs in the smallest vessels and has little affect on resistance in larger vessels
Figure 21-9 Factors Affecting Friction and Vascular Resistance p719Friction and Vessel Length
Friction and Vessel Diameter
V l L th V l Di t
Internal surfacearea 1
Internal surface area 2
Resistance to flow 1Flow 1
Resistance to flow 2
Flow 21
Greatest resistance,slowest flow near surfaces
Leastresistance,greatest flowat center
Vessel Length versus Vessel Diameter
Factors Affecting Vascular Resistance
Diameter 2 cm
Diameter 1 cm
Resistance to flow 1
Resistance to flow 16
Plaque deposit Turbulence
Turbulence
Plaque deposit Turbulence
Turbulence
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• Arterial blood pressure– Maintains blood flow through capillary beds
– Rises during ventricular systole and falls during ventricular diastole
P l i h h i ill i h
Arterial blood pressure
• Pulse is a rhythmic pressure oscillation that accompanies each heartbeat– Pulse pressure = difference between systolic and
diastolic pressures
• Mean Arterial Pressure (MAP) is a weighted average of pulse pressure and diastolic pressure
Figure 21-11 Pressures within the Systemic Circuit
Systolic
Pulsepressure
Diastolic
Mean arterialpressure
mm Hg
Venous Pressure and Venous Return
• Venous pressure, though low, determines venous return
• Venous pressures in the vena cavae are around 2mm Hg2mm Hg
• Both muscular compression and the respiratory pump assist in propelling blood toward the heart
Muscular Compression
• The contraction of skeletal muscles near a vein compress it, helping push blood toward the heart
• Valves in the veins insure that blood flows in• Valves in the veins insure that blood flows in one direction only
• Normal standing and walking causes cycles of muscle contraction that assist venous return
Respiratory Pump
• As you inhale, the increase in thoracic cavity volume decreases pressure within the pleural cavity and pulls air into the lungs and also blood into the inferior vena cava and right atrium
• As you exhale, the increasing pressure pushes blood into the right atrium from the vena cavae
• This respiratory pump is important during heavy exercise when respiration is deep and frequent
Capillary Exchange
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Capillary Exchange
• Capillary exchange is the flow of water and solutes from capillaries to interstitial space
• Most of this material is reabsorbed, but some enters the lymphatic system which thenenters the lymphatic system, which then returns it to the bloodstream
• The most important processes that move materials across capillary walls are diffusion, filtration, and reabsorption
Diffusion
• Diffusion is the passive movement of ions or compounds from a region of high concentration to a region of low concentration
• Water, ions, and small organic molecules , , greadily diffuse across capillary boundaries
• Plasma proteins and blood cells are normally unable to cross the capillary boundaries except at sinusoids, where large gaps exist
Filtration• Filtration is the removal of solutes as a
solution flows across a porous membrane (fenestrated capillaries).
• The driving force in filtration is Capillary Hydrostatic Pressure (CHP) which forcesHydrostatic Pressure (CHP) which forces water and small ions across the capillary walls
• This leaves larger solutes, blood cells, and plasma proteins behind within the vessel where they maintain the osmotic potential (blood colloidal osmotic pressure) to drive reabsorption
Figure 21-12 Capillary Filtration
Capillaryhydrostatic
pressure(CHP) Amino acid
Blood protein
Glucose
Ions
Interstitialfluid
Small solutes
Hydrogenbond
Watermolecule
Endothelialcell 2
Endothelialcell 1
Reabsorption
• Reabsorption occurs as a result of blood colloidal osmotic pressure which draws water back into the capillaries via osmosis
• Remember:– hydrostatic pressure forces water and solutes out
of the blood vessel via filtration– Reabsorption pulls water back into the blood
vessel driven by the osmotic pressure of blood cells and plasma proteins remaining in the blood vessel
In Summary
• Blood entering the capillary bed has a capillary hydrostatic pressure (CHP) of 35 mm Hg
• the blood colloid osmotic pressure (pulling water back into the blood vessel) is a constantwater back into the blood vessel) is a constant across the capillary bed at 25 mm Hg
• Blood leaving capillary bed has a CHP of 18
• So what does that all mean?
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Figure 21-13 Forces Acting across Capillary Walls
KEY
Arteriole
Filtration
CHP (Capillaryhydrostatic pressure)
Venule
BCOP (Blood colloidosmotic pressure)
NFP (Net filtrationpressure)
24 L/day 20.4 L/dayNo net fluidmovement
Reabsorption
35mmHg
25mmHg
25mmHg
25mmHg
25mmHg
18mmHg
NFP 10 mm Hg NFP 0 NFP 7 mm Hg
CHP BCOPFluid forced
out of capillary
CHP BCOPNo net
movementof fluid
BCOP CHPFluid movesinto capillary
Cardiovascular Regulation
• Homeostatic mechanisms regulate cardiovascular activity to ensure that blood flow through tissues (perfusion) meets the demands for oxygen and nutrientsdemands for oxygen and nutrients
• Regulation of cardiovascular function is accomplished via autoregulation, neural mechanisms, and endocrine mechanisms
• Section 20.4 in openstax, Figure 21-12 in Martini (section 21-3)
Autoregulation
• The pattern of blood flow within capillary beds changes in response to chemical changes in interstitial fluids
• Autoregulation causes immediate localized• Autoregulation causes immediate, localized homeostatic adjustments
• If autoregulation fails to return the system to homeostasis, neural and endocrine factors are activated
Neural Mechanisms
• Neural mechanisms respond to changes in arterial pressure (baroreceptors) or blood gas levels (chemoreceptors) at specific sites
• Cardiovascular centers of the autonomic• Cardiovascular centers of the autonomic nervous system adjust cardiac output and peripheral resistance to maintain blood pressure and ensure adequate bloodflow
Endocrine Mechanisms
• Endocrine mechanisms cause the release of hormones to enhance short term adjustments or direct long-term changes
• E NE ADH Angiotensin II Erythropoetin• E, NE, ADH, Angiotensin II, Erythropoetin, and atrial natriuretic peptide are important in cardiovascular regulation
Figure 21-14 Short-Term and Long-Term Cardiovascular Responses
Central Regulation
Autoregulation
Stimulation ofreceptors sensitiveto changes insystemic bloodpressure orchemistry
Endocrine mechanisms
If autoregulation is ineffective
Neuralmechanisms
Activation ofcardiovascularcenters
Stimulationof endocrineresponse
Long-term increasein blood volumeand blood pressure
Short-term elevationof blood pressure bysympatheticstimulation of theheart and peripheralvasoconstriction
Central regulation involves bothneural and endocrine mechanisms.Activation of the cardiovascularcenters involves both thecardioacceleratory centers (whichstimulate the heart) and the vasomotorcenters (which control the degree ofperipheral vasoconstriction). Neuralmechanisms elevate cardiac outputand reduce blood flow to nonessentialor inactive tissues. The primaryvasoconstrictor involved in neuralregulation is norepinephrine (NE).Endocrine mechanisms involvelong-term increases in blood volumeand blood pressure.
Local vasodilatorsreleased
HOMEOSTASISRESTORED
HOMEOSTASIS DISTURBED
HOMEOSTASIS
HOMEOSTASISRESTORED
Local decreasein resistanceand increase inblood flow
Inadequatelocal bloodpressure andblood flow
Normalblood pressure
and volume
• Physical stress (trauma,high temperature)
• Chemical changes(decreased O2 or pH,increased CO2 orprostaglandins)
• Increased tissue activity
Start
Autoregulation involveschanges in the patten ofblood flow within capillarybeds as precapillarysphincters open and close inresponse to chemicalchanges in the interstitialfluid. Factors that promotethe dilation of blood vesselsare called vasodilators.Local vasodilators such aslactate accelerate blood flowthrough their tissue of origin.
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Patterns of Cardiovascular Responsee s o C d ov scu espo se
• Light exercise results in– Extensive vasodilation as oxygen consumption
increases– Increased venous return through the action of muscle
Exercise and the Cardiovascular System
gcontraction and respiratory pump
– A rise in cardiac output in response to increased venous return and atrial pressure
• Heavy exercise results in– Increased blood flow to skeletal muscles– Restriction of blood flow to nonessential organs
• Trained athletes have bigger hearts and greater stroke volumes than non-athletes
• An athletes cardiac output can be half again that of a non-athlete during exercise
• Regular moderate exercise can cut the risk of heart attack in half
• Only around 8% of US adults exercise at recommended levels
Cardiovascular response to hemorrhaging: short term
• Carotid and aortic reflexes increase cardiac ouput and peripheral vasoconstriction
• Sympathetic nervous system elevates blood• Sympathetic nervous system elevates blood pressure
• E and NE increase cardiac output and ADH enhances vasoconstriction
Cardiovascular response to hemorrhaging: long term
• Decline in capillary blood pressure recalls fluids from interstitial spaces
• Aldosterone and ADH promote fluid retentionp
• Increased thirst promotes water absorption across the digestive tract
• Erythropoietin ultimately increases blood volume and improves O2 delivery
Figure 21-18 Cardiovascular Responses to Hemorrhaging and Blood Loss
Normal bloodpressure and
volume
Extensive bleedingreduces bloodpressure andvolume
HOMEOSTASISDISTURBED
Responsescoordinated by theendocrine system
R
Falling bloodpressure and
volume
Blood pressureand volume rise
HOMEOSTASISRESTORED
Elevationof bloodvolume
HOMEOSTASIS
Responsesdirected by thenervous system Long-Term Hormonal Response
ADH, angiotensin II, aldosterone,and EPO released
Cardiovascular Responses
Peripheralvasoconstriction;mobilization ofvenous reserve
Increasedcardiacoutput
Stimulation ofbaroreceptors andchemoreceptorsPain, stress,
anxiety, fear
Higher Centers
Stimulation ofcardiovascularcenters
Generalsympatheticactivation
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Circulatory Shock
• Circulatory shock is marked by low blood pressure and inadequate peripheral bloodflow
• Symptoms appear after a loss of about 30% of total blood volume
• In mild cases, homeostatic mechanisms can cope withIn mild cases, homeostatic mechanisms can cope with the situation
• When blood volume drops by more than 35% homeostatic mechanisms cannot cope and low cardiac output results in damage to the myocardium
• In the absence of treatment, damage becomes irreversible and death ensues
• The brain – The brain has a very high oxygen demand and normally
receives about 12% of Cardiac output– Four arteries anastomose inside the cranium insuring constant
blood flow
Special circulation
• The heart – Coronary arteries arise from the ascending aorta
• The lungs – Pulmonary circuit, regulated by local responses to O2 levels
within the alveoli– The pulmonary circuit responds differently than other tissues
in that a decline in O2 levels causes vasoconstriction in the lung tissues and blood is shunted to the alveoli)
The distribution of blood: General functional patterns
• Peripheral distribution of arteries and veins is generally symmetrical, except near the heart where the largest vessels connect to the atria or ventriclesventricles
• Single vessels may have several names as they cross anatomical boundaries
• Arteries and corresponding veins usually travel together
Pulmonary circuit consists of pulmonary vessels
• The pulmonary trunk gives rise to the right and left pulmonary arteries which deliver blood to the lungs
• Capillary networks in the lungs surround alveoli where gas exchange occurs
• Four pulmonary veins, two from each lung deliver blood to the left atrium
The Systemic Circuit
• The systemic circuit supplies and drains the capillary beds in parts of the body not serviced by the pulmonary circuit
• The systemic circuit begins at the left• The systemic circuit begins at the left ventricle and ends at the right atrium
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Figure 21-21 An Overview of the Major Systemic Arteries
Vertebral
Right subclavian
Brachiocephalictrunk
Ascendingaorta
Aortic arch
Celiac trunkBrachial
Right common carotid
Left common carotid
Left subclavian
Axillary
Pulmonary trunk
Descending aorta
Diaphragm
Renal
Superior mesenteric
Gonadal
Inferior mesenteric
Common iliac
Internal iliac
Radial
UlnarExternal
iliac
Femoral
Palmararches Deep
femoral
Popliteal
Posterior tibial
Anterior tibial
Fibular
Plantar arch
Descendinggenicular
Dorsalis pedis
Ascending Aorta And Aortic Arch
• The right and left coronary arteries originate from base of aortic sinus at the base of the aortic arch
• The aortic arch connects the ascending and descending aortasg
• Three elastic arteries branch from the aortic arch; the brachiocephalic, left common carotid, and left subclavian
• The brachiocephalic ascends then branches to form the right subclavian and right common carotid arteries
Figure 21-22a Arteries of the Chest and Upper Limb (Part 1 of 2)
SuprascapularThyrocervical trunk
Right subclavian
Axillary
Lateral thoracicAnterior humeral
circumflex
Posterior humeralcircumflex
Subscapular
Deep brachial
Right common carotidLeft common carotidVertebral
Brachiocephalic trunk
Left subclavian
Aortic arch
Ascending aorta
Thoracic aorta
Heart
Thoracoacromial
Deep brachial
Intercostal arteries
Brachial
Ulnar recurrent arteries
Internal thoracic
Abdominal aortaUlnar collateral arteries
Arteries of the chest and upperlimb, a diagrammatic view
Figure 21-22b Arteries of the Chest and Upper Limb
Right vertebral Rightcommoncarotid
Leftcommoncarotid
Leftvertebral
Leftthyrocervical
trunkLeftsubclavian
Brachiocephalictrunk
Right thyrocervicaltrunk
Rightsubclavian
Right axillary
Right internalthoracic
Leftinternalthoracic Left
axillary
AORTICARCHMuscles of the right
pectoral region and
Skin and muscles ofchest and abdomen,mammary gland (right
Spinal cord, cervical vertebrae(right side); fuses with left vertebral,forming basilar artery after enteringcranium via foramen magnum
Muscles, skin, tissues of neck, thyroid gland, shoulders, and upper back (right side)
axillary
ASCENDINGAORTA
THORACICAORTA
(see Fig. 2125)
Leftbrachial
Leftulnar
Leftradial
ABDOMINALAORTA
(see Fig. 2126)
LEFTVENTRICLE
Right brachial
Right radial Right ulnar
Connected by anastomosesof palmar arches that supply
digital arteries
To structures of thearm
Forearm,radial side
Forearm,ulnar side
axilla side), pericardium
A flowchart of the arteries of the chest and upper limb
Figure 21-23 Arteries of the Neck and Head
Branches of theExternal Carotid
Superficialtemporal
Maxillary
Occipital
Facial
LingualI t l tid
Basilar
Posterior cerebral
Carotid canal
Cerebral arterial circle
OphthalmicMiddle cerebral
Anterior cerebral
gExternalcarotid
Common carotid
Brachiocephalictrunk
Second rib
Internal thoracicAxillary
Subclavian
SuprascapularTransverse cervical
Thyrocervicaltrunk
Carotid sinusVertebral
Internal carotid
Inferior thyroid
Descending Aorta
• The descending aorta is continuous with the aortic arch and is divided into the superior thoracic aorta and inferior abdominal aorta by the diaphragmthe diaphragm
12
Figure 21-25a Major Arteries of the Trunk
Aortic arch
Internal thoracic
Thoracic aorta
Somatic Branches ofthe Thoracic Aorta
Intercostal arteries
Superior phrenic
Inferior phrenic
Diaphragm
Visceral Branches ofthe Thoracic Aorta
Bronchial arteries
Esophageal arteries
Mediastinal arteries
Pericardial arteries
Adrenal
Renal
Gonadal
Lumbar
Terminal segmentof the aorta
Common iliac
Median sacral
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
Figure 21-27 Arteries of the Lower LimbCommon
iliac
Externaliliac
Superiorgluteal
Inguinalligament
Deepfemoral
Lateralfemoral
circumflex
Medialfemoral
circumflex
Femoral
Internaliliac
Lateralsacral
Internalpudendal
Obturator
Descendinggenicular
Superior gluteal
Right externaliliac
Deep femoral
Lateral femoralcircumflex
EXTERNAL ILIAC
Popliteal
Anterior tibial
Posteriortibial
Fibular
Dorsalis pedis
Medial plantar
Lateral plantar
Dorsal arch
Plantar arch
Anterior view Posterior view A flowchart of blood flow to a lower limb
Deepfemoral
Femoral
Descendinggenicular
Popliteal
Fibular Posteriortibial
Anteriortibial
Medialfemoral
circumflex
Lateralfemoral
circumflex
Thigh
Hip joint, femoral head, deepmuscles of the thigh
Skin of leg,knee joint
Leg andfoot
Quadricepsmuscles
Adductor muscles,obturator muscles,hip joint
Connected by anastomoses ofdorsalis pedis, dorsal arch, andplantar arch, which supply distalportions of the foot and the toes
• The superior vena cava drains blood from the head and neck
• The inferior vena cava drains blood from the remainder of the body
Systemic Veins
remainder of the body
Figure 21-28 An Overview of the Major Systemic Veins
VertebralExternal jugular Internal jugular
Brachiocephalic
Superior vena cava
Intercostal veins
Inferior vena cavaRenal
Gonadal
Subclavian
AxillaryCephalicBrachial
Basilic
Hepatic veins
Median cubital
Radial
Ulnar
Median antebrachial
Lumbar veins
Left and rightcommon iliac
External iliacInternal iliacPalmar venous arches
Digital veins
Internal iliac
Deepfemoral
Femoral
Posterior tibial
Anterior tibial
Great saphenous
Popliteal
Small saphenous
Fibular
Plantar venous archDorsal venous arch
Superficial veins
Deep veins
KEY
13
Figure 21-29a Major Veins of the Head, Neck, and Brain
Cerebral veins
Cavernous sinus
P t l i
Superior sagittal,sinus (cut)
An inferior view of the brain, showing the venous distribution. For the relationship of these veins to meningeal layers, see Figure 14-3, p. 453.
Occipital sinus
Straight sinus
Transverse sinus
Cerebellar veins
Sigmoid sinus
Internal jugular
Petrosal sinus
Figure 21-29c Major Veins of the Head, Neck, and Brain
Superior sagittal sinus
Superficial cerebral veins
Inferior sagittal sinus
Great cerebralStraight sinus
Petrosal sinusesRight transverse sinus
Occipital sinus
Sigmoid sinus
Occipital
TemporalDeep cerebral
Cavernous sinusMaxillary
Facial
Occipital
Vertebral
External jugular
Right subclavian
Axillary
Clavicle
Veins draining the brain and the superficialand deep portions of the head and neck.
Internal jugular
Right brachiocephalic
Left brachiocephalic
Superior vena cavaInternal thoracic
Figure 21-30 The Venous Drainage of the Abdomen and Chest
M di bi l
Adrenal veinsPhrenic veins
Basilic
INFERIOR VENA CAVA
Intercostal veins
HemiazygosAccessory hemiazygos
CephalicAxillaryBrachiocephalicHighest intercostalSubclavian
External jugularInternal jugularVertebral
Lumbar
Gonadalveins
Renal veins
Hepaticveins
Internalthoracic
Azygos
Esophagealveins
Mediastinalveins
SUPERIORVENA CAVA
Brachial
Palmar venousarches
Digital veins
Ulnar
Median antebrachial
Radial
Cephalic
Anterior cruralinterosseous
Medialsacral
Basilic
Median cubital
Deep veins
Superficial veinsKEY
External iliac
Internal iliac
Common iliac
Lumbarveins
Figure 21-32 Venous Drainage from the Lower Limb External iliacCommon iliac
Internal iliacGluteal
Internal pudendal
Lateral sacral
ObturatorFemoral
Femoral circumflex
Deep femoral
Femoral
Great saphenous
Popliteal
Smallsaphenous
Anterior tibial
Posterior tibial
Fibular
Dorsal venous arch
Plantar venous archDigital
An anterior view A posterior view
EXTERNAL ILIAC
Smallsaphenous
Femoral
Popliteal
FibularPosterior
tibialAnterior
tibial
Extensive anastomoses interconnectveins of the ankle and foot
Greatsaphenous
KEYSuperficial veins
Deep veins
Collects bloodfrom thesuperficial veinsof the lower limb
Collects bloodfrom the thigh
Collects bloodfrom superficialveins of the legand foot
A flowchart of venous circulation from a lower limb
Deepfemoral
14
The Hepatic Portal System
• Blood leaving capillaries supplied by the celiac, superior, and inferior mesenteric arteries flows into the hepatic portal system
• This blood contains substances absorbed by the stomach and intestinesstomach and intestines
• At the liver these compounds are stored, metabolized into other compounds or excreted
• After flowing through the sinusoids of the liver, blood collects in the hepatic portal vein and is discharged into the inferior vena cava
Figure 21-33 The Hepatic Portal System
Inferior vena cava
Hepatic
Cystic
Hepatic portal
Pancreaticoduodenal
Superior MesentericVein and Its Tributaries
Middle colic (fromtransverse colon)
Left gastric
Right gastric
Stomach
Spleen
Pancreas
Left gastroepiploic(stomach)
Right gastroepiploic(stomach)
Pancreatic
Descending colon
Splenic Vein and ItsTributaries
Inferior Mesenteric
Liver
transverse colon)
Right colic (ascendingcolon)
Ileocolic (Ileum andascending colon)
Intestinal (small intestine)
Vein and Its Tributaries
Left colic (descendingcolon)
Sigmoid(sigmoid colon)
Superior rectal (rectum)
• Fetal blood flow to the placenta is supplied via paired umbilical arteries
• A single umbilical vein drains from the placenta t th d t hi h ll t bl d f
Fetal Bloodflow
to the ductus venosus, which collects blood from both the umbilical vein and liver and empties into the inferior vena cava
Fetal Circulation of the Heart and Great Vessels
• There is no need for pulmonary function in the fetus
• Two shunts bypass the pulmonary circuit – Foramen ovale or interatrial opening allows blood to
flow from the right to left atrium
– Ductus arteriosus connects the pulmonary and aortic trunks
Cardiovascular Changes at Birth
• At birth the lungs and pulmonary vessels expand
• The ductus arteriosus constricts and becomes ligamentum arteriosum
• A valvular flap closes the foramen ovale
15
Figure 21-34a Fetal Circulation
AortaForamen ovale (open)
Ductus arteriosus (open)
Pulmonary trunk
Li
Placenta
Liver Inferiorvena cavaDuctusvenosus
Umbilicalvein
Umbilical cord
Blood flow to and from the placenta in full-term fetus (before birth)
Umbilicalarteries
Figure 21-34b Fetal Circulation
Right atrium
Foramen ovale(closed)
Left atrium
Pulmonary trunk
Ductus arteriosus(closed)
Blood flow through theneonatal (newborn) heartafter delivery
Inferiorvena cava
Right ventricle
Left ventricle