2Module 17.3: Red blood cell production and recycling RBC production and recyclingEvents occurring in red bone marrowBlood cell formation (erythropoiesis) occurs only in red bone marrow (myeloid tissue)Located in vertebrae, ribs, sternum, skull, scapulae, pelvis, and proximal limb bonesFatty yellow bone marrow can convert to red bone marrow in cases of severe, sustained blood lossDeveloping RBCs absorb amino acids and iron from bloodstream and synthesize Hb
3Module 17.3: Red blood cell production and recycling StagesProerythroblastsErythroblastsActively producing HbAfter four days becomes normoblastReticulocyte (80% of mature cell Hb)Ejects organelles including nucleusEnters bloodstream after two daysAfter 24 hours in circulation, is mature RBC
4Module 17.3: Red blood cell production and recycling Events occurring at macrophagesEngulf old RBCs before they rupture (hemolyze)Hemoglobin recyclingIronStored in phagocyteReleased into bloodstream attached to plasma protein (transferrin)Globular proteins disassembled into amino acids for other usesHeme biliverdin bilirubin bloodstreamHemoglobin not phagocytized breaks down into protein chains and eliminated in urine (hemoglobinuria)Excess of bilirubin =jaundice
5Module 17.3: Red blood cell production and recycling Events occurring at liverBilirubin excreted into bileAccumulating bile due to diseases or disorders can lead to yellowish discoloration of eyes and skin (jaundice)Events occurring at the large intestineBacteria convert bilirubin to urobilins and stercobilins which become part of fecesGive feces yellow-brown or brown coloration
6Module 17.3: Red blood cell production and recycling Events occurring at kidneysExcrete some hemoglobin and urobilinsGive urine its yellow colorPresence of intact RBCs in urine (hematuria)Only after urinary tract damage
7Fe2+ transported in circulation Events Occurring in the Red Bone MarrowStartDeveloping RBCs absorb aminoacids and Fe2+ from the bloodstreamand synthesize new Hb molecules.Cells destines to become RBCs firstdifferentiate into proerythroblasts.Proerythroblasts then differentiateinto various stages of cells callederythroblasts, which activelysynthesize hemoglobin.Erythroblasts are namedaccording to total size, amount ofhemoglobin present, and size andappearance of the nucleus.Events in the life cycle of RBCsEvents Occurring inMacrophagesMacrophages in liver,spleen, and bone marrowFe2+Fe2+ transported in circulationby transferrinRBCformationHemeAmino acidsAverage life span ofRBC is 120 days90%BiliverdinAfter roughly four days of differentiation, theerythroblast, now called a normoblast, shedsits nucleus and becomes a reticulocyte(re-TIK-ū-lō-sīt), which contains 80 percent ofthe Hb of mature RBC.Old anddamagedRBCsBilirubin10%In the bloodstream,the rupture of RBCsis called hemolysis.Ejection ofnucleusAfter two days in the bone marrow,reticulocytes enter the bloodstream. After 24hours in circulation, the reticulocytescomplete their maturation and becomeindistinguishable from other mature RBCs.Figure 17.3 Red blood cells are continuously produced and recycledBilirubin boundto albumin inbloodstreamHemoglobin that is not phagocytizedbreaks down, and the alpha and betachains are eliminated in urine. Whenabnormally large numbers of RBCsbreak down in the bloodstream, urinemay turn red or brown. This conditionis called hemoglobobinuria.New RBCsreleased intocirculationLiverBilirubinEvents Occurring in the KidneyExcretedin bileAbsorbed into the circulationHbEvents Occurring inthe LiverUrobilinsBilirubinUrobilins,sterconilinsEliminatedin fecesEliminatedin urineEvents Occurring in the Large IntestineFigure 17.37
8Module 17.3 Review a. Define hemolysis. b. Identify the products formed during the breakdown of heme.c. In what way would a liver disease affect the level of bilirubin in the blood?
9Module 17.4: Blood types Blood types Determined by presence or absence of cell surface markers (antigens)Are genetically determined glycoproteins or glycolipidsCan trigger a protective defense mechanism (immune response)Identify blood cells as “self” or “foreign” to immune systemMore than 50 blood cell surface antigens existThree particularly importantA, B, Rh (or D)
10Module 17.4: Blood types Four blood types (AB antigens) Type A (A surface antigens)Anti-B antibodies in plasmaType B (B surface antigens)Anti-A antibodies in plasmaType AB (Both A and B surface antigens)No anti-A or anti-B antibodies in plasmaType O (no A or B surface antigens)Both anti-A and anti-B antibodies in plasma
11The characteristics of blood for each of the four blood types Type AType BType ABType OType A blood has RBCswith surface antigen A only.Type B blood has RBCswith surface antigen B only.Type AB blood has RBCswith both A and B surfaceantigens.Type O blood has RBCslacking both A and Bsurface antigens.Surfaceantigen ASurfaceantigen BFigure Blood type is determined by the presence or absence of specific surface antigens on RBCsIf you have Type A blood,your plasma contains anti-Bantibodies, which will attackType B surface antigens.If you have Type B blood,your plasma contains anti-Aantibodies.If you have Type AB blood,your plasma has neitheranti-A nor anti-B antibodies.If you have Type O blood,your plasma contains bothanti-A and anti-B antibodies.Figure11
12Module 17.4: Blood types Rh surface antigens Separate antigen from A or BPresence or absence on RBC determines positive or negative blood type respectivelyExamples: AB+, O–
13Figure Blood type is determined by the presence or absence of specific surface antigens on RBCsFigure13
14Module 17.4 Reviewa. What is the function of surface antigens on RBCs?b. Which blood type(s) can be safely transfused into a person with Type O blood?
15CLINICAL MODULE 17.5: Newborn hemolytic disease Genetically determined antigens mean that a child can have a blood type different from either parentDuring pregnancy, the placenta restricts direct transport between maternal and infant bloodAnti-A and anti-B antibodies are too large to crossAnti-Rh antibodies can crossCan lead to mother’s antibodies attacking fetal RBCs
16CLINICAL MODULE 17.5: Newborn hemolytic disease First pregnancy with Rh– mother and Rh+ infantDuring pregnancy, few issues occur because no anti-Rh antibodies exist in maternal circulationDuring birth, hemorraging may expose maternal blood to fetal Rh+ cellsLeads to sensitization or activation of mother’s immune system to produce anti-Rh antibodies
17Rh–motherFirst Pregnancy of an Rh– Motherwith an Rh+ infantRh+fetusThe most common form of hemolytic disease ofthe newborn develops after an Rh– women hascarried an Rh+ fetus.During First PregnancyProblems seldom develop during afirst pregnancy, because very few fetalcells enter the maternal circulationthen, and thus the mother’s immunesystem is not stimulated to produceanti-Rh antibodies.Maternal blood supplyand tissuePlacentaFigure Hemolytic disease of the newborn is an RBC-related disorder caused by a cross-reaction between fetal and maternal blood typesFetal blood supplyand tissueExposure to fetal red blood cellantigens generally occurs duringdelivery, when bleeding takes place atthe placenta and uterus. Such mixingof fetal and maternal blood canstimulate the mother’s immune systemto produce anti-Rh antibodies, leadingto sensitization.Hemorrhaging at DeliveryMaternal blood supplyand tissueRh antigen onfetal red blood cellsFetal blood supplyand tissueRoughly 20 percent of Rh– motherswho carried Rh+ children becomesensitized within 6 months of delivery.Because the anti-Rh antibodies are notproduced in significant amounts untilafter delivery, a woman’s first infant isnot affected.Maternal Antibody ProductionMaternal blood supplyand tissueMaternal antibodiesto Rh antigenFigure 17.517
18CLINICAL MODULE 17.5: Newborn hemolytic disease Second pregnancy with Rh– mother and Rh+ infantSubsequent pregnancy with Rh+ infant can allow maternal anti-Rh antibodies to cross placental barrierAttack fetal RBCs and cause hemolysis and anemia= Erythroblastosis fetalisFull transfusion of fetal blood may be necessary to remove maternal anti-Rh antibodiesPreventionRhoGAM antibodies can be administered to maternal circulation at 26–28 weeks and before/after birthDestroys any fetal RBCs that cross placentaPrevents maternal sensitization
19Second Pregnancy of an Rh– Mother with an Rh+ Infant fetusIf a subsequent pregnancy involves an Rh+ fetus,maternal anti-Rh antibodies produced after thefirst delivery cross the placenta and enter thefetal bloodstream. These antibodies destroyfetal RBCs, producing a dangerous anemia.The fetal demand for blood cells increases,and they begin leaving the bone marrow andentering the bloodstream before completingtheir development. Because these immatureRBCs are erythroblasts, HDN is also knownas erythroblastosis fetalis. Fortunately, themother’s anti-Rh antibody production canbe prevented if such antibodies (availableunder the name RhoGAM) are administeredto the mother in weeks 26–28 of pregnancyand during and after delivery. Theseantibodies destroy any fetal RBCs thatcross the placenta before they can stimulatea maternal immune response. Becausematernal sensitization does not occur, noanti-Rh antibodies are produced.Figure Hemolytic disease of the newborn is an RBC-related disorder caused by a cross-reaction between fetal and maternal blood typesDuring Second PregnancyMaternal blood supplyand tissueMaternal anti-RhantibodiesFetal blood supplyand tissueHemolysis offetal RBCsFigure 17.519
20CLINICAL MODULE 17.5 Review a. Define hemolytic disease of the newborn (HDN).b. Why is RhoGAM administered to Rh– mothers?
21Module 17.6: White blood cells White blood cells (leukocytes)Spend only a short time in circulationMostly located in loose and dense connective tissues where infections often occurCan migrate out of bloodstreamContact and adhere to vessel walls near infection siteSqueeze between adjacent endothelial cells= EmigrationAre attracted to chemicals from pathogens, damaged tissues, or other WBCs= Positive chemotaxis
22Module 17.6: White blood cells White blood cell typesGranular leukocytes (have cytoplasmic granules)NeutrophilEosinophilBasophilAgranular leukocytes (lacking cytoplasmic granules)MonocyteLymphocyteChanging populations of different WBC types associated with different conditions can be seen in a differential WBC count
23Module 17.6: White blood cells Granular leukocytesNeutrophilsMultilobed nucleusPhagocytic cells that engulf pathogens and debrisEosinophilsGranules generally stain bright redPhagocytic cells that engulf antibody-labeled materialsIncrease abundance with allergies and parasitic infectionsBasophilsGranules generally stain blueRelease histamine and other chemicals promoting inflammation
24The structure and function of white blood cells (leukocytes)GRANULAR LEUKOCYTESNeutrophilEosinophilBasophilWBCs can bedivided intotwo classesFigure White blood cells defend the body against pathogens, toxins, cellular debris, and abnormal or damaged cellsShared Properties of WBCsAGRANULAR LEUKOCYTES• WBCs circulate for only a short portion of theirlife span, using the bloodstream primarily totravel between organs and to rapidly reachareas of infection or injury. White blood cellsspend most of their time migrating throughloose and dense connective tissues throughoutthe body.MonocyteLymphocyte• All WBCs can migrate out of the bloodstream.When circulating white blood cells in thebloodstream become activated, they contactand adhere to the vessel walls and squeezebetween adjacent endothelial cells to enter thesurrounding tissue. This process is calledemigration, or diapedesis (dia, through;pedesis, a leaping).• All WBCs are attracted to specific chemicalstimuli. This characteristic, called postivechemotaxis (kē-mō-TAK-sis), guides WBCs toinvading pathogens, damaged tissues, andother active WBCs.• Neutrophils, eosinophils, and monocytes arecapable of phagocytosis. These phagocytes canengulf pathogens, cell debris, or othermaterials. Macrophages are monocytes thathave moved out of the bloodstream and havebecome actively phagocytic.Figure 17.624
25Module 17.6: White blood cells Agranular leukocytesMonocytesLarge cells with bean-shaped nucleusEnter tissues and become macrophages (phagocytes)LymphocytesSlightly larger than RBC with large round nucleusProvide defense against specific pathogens or toxins
26Module 17.6 Review a. Identify the five types of white blood cells. b. How do basophils respond during inflammation?
27Module 17.7: Formed element production Formed elementsAppropriate term since platelets are cell fragmentsPlateletsStructure: flattened discs that appear round when viewed from top but spindle-shaped in blood smearFunction: clump together and stick to damaged vessel walls where they release clotting chemicalsImmediate precursor cell is megakaryocyte (mega-, big + karyon, nucleus + -cyte, cell)Platelets average 350,000 ul; continuously replaced every 9-12 days. Stick together at damaged
28Module 17.8: Hemostasis Hemostasis (haima, blood + stasis, halt) Stops blood loss from damaged blood vessel wallsEstablishes framework for tissue repairs
30Section 2: Functional Anatomy of Blood Vessels Blood vessels conduct blood between heart and peripheral tissuesTwo circuitsPulmonary circuit (to and from lungs)Systemic circuit (to and from rest of body)Each circuit begins and ends with heartOccur in sequence
31Section 2: Functional Anatomy of Blood Vessels Specific vesselsArteries (transport blood away from heart)Veins (transport blood to the heart)Capillaries (exchange substances between blood and tissues)Interconnect smallest arteries and smallest veins
32Section 2: Functional Anatomy of Blood Vessels General circulation pathway through circuitsRight atrium (entry chamber) from systemic circuit to right ventricle, to pulmonary circuitPulmonary circuitPulmonary arteries to pulmonary capillaries to pulmonary veinsLeft atrium from pulmonary circuit to left ventricle, to systemic circuitSystemic circuitSystemic arteries to systemic capillaries to systemic veins
33Figure 17 Section 2 The Functional Anatomy of Blood Vessels 33
34Module 17.10: Arteries and veins Both arteries and veins have three layersTunica intima (tunica interna)Innermost layerEndothelial cells with connective tissue with elastic fibersIn arteries, outer margin has layer of elastic fibers (internal elastic membrane)Tunica mediaMiddle layerContains concentric sheets of smooth muscleCapable of vasoconstriction or vasodilationCollagen fibers connect tunica media to other layers
35Module 17.10: Arteries and veins Both arteries and veins have three layers (continued)Tunica externaOutermost layerConnective tissue sheath with collagen and elastic fibersGenerally thicker in veinsAnchor vessel to surrounding tissues
36A photomicrograph of an artery and an adjacent vein Figure Arteries and veins differ in the structure and thickness of their wallsLM x 60Figure36
37The structure of the wall of an artery Artery Tunica intimaSmoothmuscleInternal elasticmembraneFigure Arteries and veins differ in the structure and thickness of their wallsExternalelasticmembraneTunica mediaEndotheliumElastic fiberTunica externaFigure37
38The structure of the wall of a vein Vein Endothelium Smooth muscle Figure Arteries and veins differ in the structure and thickness of their wallsSmooth muscleTunica intimaTunica mediaTunica externaFigure38
39Module 17.10: Arteries and veins Five general blood vessel classesArteriesElastic arteries (large vessels close to the heart that stretch and recoil when heart beats)Muscular arteries (medium-sized arteries, distribute blood to skeletal muscles and internal organs)ArteriolesPoorly defined tunica externa and tunica media only 1–2 smooth muscle cells thickCapillariesThin, exchange vessels
40Module 17.10: Arteries and veins Five general blood vessel classes (continued)Venules (small veins lacking tunica media, collect blood from capillaries)VeinsMedium-sized veins (tunica media is thin but tunica externa is thick with longitudinal collagen and elastic fibers)Large veins (superior and inferior venae cavae and tributaries having thin tunica media)
41The five general classes of blood vessels: arteries, arterioles, capillaries, venules, and veinsLarge VeinsElastic ArteriesInclude the superior and inferior venae cavaeand their tributaries; contain all three vesselwall layers; have a slender tunica mediacomposed of a mixture of elastic andcollagen fibersLarge vessels that transport blood away fromthe heart; include the pulmonary trunk andthe aorta and its major branches; are resilent,elastic vessels capable of stretching andrecoiling as the heart beatsand arterial pressureschangeTunica externaInternal elastic layerTunica mediaTunica intimaTunica intimaTunica mediaTunica externaMedium-sized VeinsMuscular ArteriesRange from 2 to 9 mm in internal diameter;the tunica media is thin and containsrelatively few smooth muscle cells; thethickest layer is the tunica externa, whichcontains longitudinal bundles ofelastic and collagen fibersMedium-sized arteries that distribute bloodto the body’s skeletal muscles and internalorgansFigure Arteries and veins differ in the structure and thickness of their wallsTunica externaTunica externaTunica mediaTunica mediaTunica intimaTunica intimaVenulesArteriolesCollect blood from capillary beds and are thesmallest venous vessels; those smaller than50 μm lack a tunica media andresemble expanded capillariesHave a poorly defined tunica externa, andthe tunica media consists of onlyone or two layers of smooth musclecellsTunica externaSmooth muscle cellsEndotheliumEndotheliumCapillariesThe only blood vessels whose walls permit exchangebetween the blood and the surrounding interstitialfluids due to thin walls and shortdiffusion distancesPoresEndothelial cellsEndothelial cellsBasal laminaBasal laminaFigure41
42Module 17.10 Review a. List the five general classes of blood vessels. b. Describe a capillary.c. A cross section of tissue shows several small, thin-walled vessels with very little smooth muscle tissue in the tunica media. Which type of vessels are these?
43Module 17.11: CapillariesTypical capillary consists of tube of endothelial cells with delicate basal laminaNeither tunica intima nor externa are presentAverage diameter = 8 µmAbout the same as an RBCTwo major categoriesContinuous capillariesFenestrated capillaries
44Module 17.11: Capillaries Continuous capillaries Endothelium is a complete liningLocated throughout body in all tissues except epithelium and cartilagePermit diffusion of water, small solutes, and lipid-soluble materialsPrevent loss of blood cells and plasma proteinsSome selective vesicular transportSome capillaries have endothelial tight junctionsRestricted and regulated permeability
45Module 17.11: Capillaries Fenestrated capillaries Contain windows or pores penetrating endotheliumPermit rapid exchange of water and larger solutesExamples: capillaries in brain and endocrine organs, absorptive areas of GI tract, kidney filtration sites
46materials transported across the endothelial cell The two major types of capillaries:continuous capillaries and fenestrated capillariesBasal laminaEndothelial cellNucleusFigure Capillary structure and capillary blood flow affect the rates of exchange between the blood and interstitial fluidA continuous capillaryA fenestrated capillaryFenestrations,or poresVesicles containingmaterials transportedacross the endothelial cellBoundarybetweenendothelialcellsBoundarybetweenendothelialcellsBasallaminaBasallaminaFigure – 246
47Module 17.11: Capillaries Sinusoids Resemble fenestrated capillaries that are flattened and irregularly shapedCommonly have gaps between endothelial cellsBasal lamina is thin or absentPermit more water and solute (plasma proteins) exchangeOccur in liver, bone marrow, spleen, and many endocrine organs
48A sinusoid Gap between adjacent cells Figure Capillary structure and capillary blood flow affect the rates of exchange between the blood and interstitial fluidFigure48
49Module 17.11: Capillaries Capillary bed Network of capillaries with several connections between arterioles and venulesCan have collateral arteries (functionally redundant) fusing to one arteriole (forming an arterial anastomosis) leading to capillary bedCan be bypassed by arteriovenous anastomosis that directly connects arteriole to venule
50Module 17.11: Capillaries Capillary bed (continued) Thoroughfare channels (direct passages through capillary bed)Begin with metarteriole segment that can constrict or dilate to control flowHas multiple capillaries connecting to venulesHave bands of smooth muscle (precapillary sphincters) to control flow into capillary bedVasomotion (cycling contraction and relaxing changing capillary bed flow)
51A capillary bed Collateral arteries Vein Venule Arteriole Metarteriole ThoroughfarechannelSmoothmuscle cellsCapillariesFigure Capillary structure and capillary blood flow affect the rates of exchange between the blood and interstitial fluidPrecapillarysphincterSmallvenulesArteriovenousanastomosisKEYPrecapillary sphinctersContinuousblood flowVariableblood flowFigure51
52Module 17.11 Review a. Identify the two types of capillaries. b. At what sites in the body are fenestrated capillaries located?c. Why do capillaries permit the diffusion of materials, whereas arteries and veins do not?
53Module 17.12: Venous functional anatomy Venous functional anatomy and pressureBlood pressure in venules and medium veins is <10% of that in ascending aorta (largest artery)These vessels contain valves (folds of tunica intima) that ensure one-way flow of blood toward heartMalfunctioning valves can lead to varicose veins (enlarged superifical thigh and leg veins) or distortion of adjacent tissues (hemorrhoids)
54FigureFigure The venous system has low pressures and contains almost two-thirds of the body's blood volume54
55Module 17.12: Venous functional anatomy Increasing venous blood flowSkeletal muscle contractions squeezing veins with valvesSympathetically controlled constriction of veins (venoconstriction)Venoconstriction can maintain arterial blood volume despite hemorrhaging
56Total blood volume distribution FigureTotal blood volume distributionUnevenly distributed between arteries, veins, and capillariesSystemic venous system contains nearly 2/3 of total blood volume (~3.5 L)Of that , ~1 L is in venous networks of liver, bone marrow, and skinSystemicvenoussystemPulmonarycircuitHeartarterialcapillariesThe distribution of blood volume within the bodyvenousFigure The venous system has low pressures and contains almost two-thirds of the body's blood volume56
57Module 17.12 Review a. Define varicose veins. b. Why are valves located in veins, but not in arteries?c. How is blood pressure maintained in veins to counter the force of gravity?
58Module 17.13: Pulmonary circuit Arteries of pulmonary circuit differ from those in systemic circuitPulmonary arteries carry deoxygenated bloodRight ventricle pulmonary trunk (large artery) pulmonary arteries pulmonary arterioles pulmonary capillaries (surrounded by alveoli, where gasexchange occurs) pulmonary venules pulmonary veins left atrium
60The path of blood flow through the pulmonary circuit Aortic archAscending aortaPulmonary trunkSuperior vena cavaLeft lungLeftpulmonaryarteriesRight lungRightpulmonaryarteriesLeftpulmonaryveinsFigure The pulmonary circuit, which is relatively short, carries deoxygenate blood from the right ventricle to the lungs and returns oxygenated blood to the left atriumRightpulmonaryveinsAlveolusCapillaryInferior vena cavaDescending aortaFigure60
61Module 17.13: Pulmonary circuit Major patterns of blood vessel organizationPeripheral arteries and veins are generally identical between left and right sides except near heartVessels change names as they branch or move into new areasTissues and organs are usually served by many arteries and veinsAnastomoses reduce impact of potential blockages (occlusions)
62Module Reviewa. Identify the two circulatory circuits of the cardiovascular system.b. Briefly describe the three major patterns of blood vessel organization.c. Trace a drop of blood through the lungs, beginning at the right ventricle and ending at the left atrium.
63Module 17.14: Systemic vessels Arterial systemOriginates from aorta (largest elastic vessel exiting left ventricle)Venous systemAll drain into:Superior vena cava (upper limbs, head, and neck)Inferior vena cava (trunk and lower limbs)
64An overview of the systemic arterial system VertebralCommon carotidSubclavianBrachiocephalictrunkAxillaryAortic archAscendingaortaDescending aortaBrachialDiaphragmCeliac trunkRenalGonadalLumbarRadialCommon iliacInternal iliacUlnarExternal iliacFigure The systemic arterial and venous systems operate in parallel, and the major vessels often have similar namesPalmararchesDigitalarteriesDeepfemoralFemoralPoplitealPosterior tibialAnterior tibialFibularDorsalis pedisPlantar archFigure64
65An overview of the systemic venous system VertebralExternal jugularInternal jugularSubclavianBrachiocephalicAxillarySuperior vena cavaBrachialCephalicDiaphragmBasilicInferior vena cavaRenalGonadalRadialLumbarMedianantebrachialCommon iliacUlnarInternaliliacFigure The systemic arterial and venous systems operate in parallel, and the major vessels often have similar namesPalmarvenousarchesExternaliliacDigitalveinsDeepfemoralFemoralGreat saphenousPoplitealSmall saphenousPosterior tibialFibularAnterior tibialKEYPlantar venous archSuperficial veinsDorsal venous archDeep veinsFigure65
66Module 17.14: Systemic vessels Arteries and veins are usually similar on both sides of bodyOne significant difference between arteries and veins is distribution in the neck and limbsArteries: deep in skin, protected by bones and soft tissuesVeins: generally two sets, one deep and one superficialImportant in controlling body temperatureVenous blood flows superficially in hot weather to radiate heatVenous blood flows deep in cold weather to conserve heat
67Module Reviewa. Name the two large veins that collect blood from the systemic circuit.b. Identify the largest artery in the body.c. Besides containing valves, cite another major difference between the arterial and venous systems.
68Module 17.15: Upper limb vessels ArteriesBranches of aortic archBrachiocephalic trunkRight subclavian (right arm)Right common carotid artery (right side head & neck)Left common carotid artery (left side head & neck)Left subclavian artery (left arm)
70Module 17.15: Upper limb vessels Arteries (continued)Arteries of the forearmRadial artery (follows radius)Ulnar artery (follows ulna)Palmar arches (hand)Digital arteries (thumb and fingers)
71The branches of the aortic arch and the arteries they give rise toBranches of the Aortic ArchStartBrachiocephalictrunkLeft commoncarotid arteryLeft subclavianarteryThe Right Subclavian ArteryVertebralMajor branches of thesubclavian arteryInternalthoracicAortic archAxillaryAscendingaortaDeepbrachialArteries of the ArmHeartBrachialUlnarcollateralarteriesDescendingaortaFigure The branches of the aortic arch supply structures that are drained by the superior vena cavaRadialArteries of the ForearmUlnarDeep palmar archSuperficial palmar archDigital arteriesFigure 17.1571
72Veins of the NeckThe veins that drain into the superior vena cavaExternaljugular veinInternaljugular veinVertebral veinBrachiocephalic veinThe Right Subclavian VeinVeins of the ArmAxillary veinCephalic veinSuperior vena cavaVeins of the ForearmBrachialMedian cubital veinBasilicFigure The branches of the aortic arch supply structures that are drained by the superior vena cavaMedian antebrachial veinSuperior vena cavaKEYCephalicSuperficial veinsDeep veinsRadialBasilicUlnarDigital veinsDeep palmar archStartSuperficialpalmar archFigure 17.1572
73Module 17.15: Upper limb vessels VeinsDigital veins (empty from thumb and fingers)Veins of the forearmSuperficial palmar arch (hand)Median antebrachial vein (anterior forearm)Cephalic veinBasilic veinMedian cubital vein (interconnects cephalic and basilic veins)Venous samples usually collected here
74Module 17.15: Upper limb vessels Veins (continued)Veins of the armCephalic vein (lateral side of arm)Basilic vein (median side of arm)Brachial vein (median area of arm)Right subclavian veinMerging of axillary vein and cephalic vein
75Module 17.15: Upper limb vessels Veins (continued)Veins of the neckExternal jugular vein (drains superficial head & neck)Internal jugular vein (drains deep head & neck)Vertebral vein (cervical spinal cord and posterior skull)Veins draining into superior vena cava (SVC)Internal thoracic vein (intercostal veins)Brachiocephalic vein (jugular, axillary, vertebral, and internal thoracic veins)
76Module Reviewa. Name the two arteries formed by the division of the brachiocephalic trunk.b. A blockage of which branch from the aortic arch would interfere with blood flow to the left arm?c. Whenever Thor gets angry, a large vein bulges in the lateral region of his neck. Which vein is this?
77Module 17.16: Head and neck vessels ArteriesCommon carotid artery (head and neck)Palpated alongside trachea (windpipe)Contains carotid sinus (with baroreceptors monitoring blood pressure)Branches of common carotid arteryExternal carotid artery (neck, esophagus, pharynx, larynx, lower jaw, cranium, and face on that side)Internal carotid artery (brain and eyes)Vertebral artery (enters cranium and fuses with basilar artery along ventral medulla oblongata)
78Areas supplies by the external carotid, internal carotid, and vertebral arteries Carotid canalBasilarSuperficialtemporalMaxillaryBranches of theExternal CarotidOccipitalFacialInternal carotidarteryLingualFigure The external carotid arteries supply the neck, lower jaw, and face, and the internal carotid and vertebral arteries supply the brain, while the external jugular veins drain the regions supplied by the external carotids, and the internal jugular veins drain the brainExternalcarotidVertebral arteryCarotid sinusCommon carotid arteryClavicleFirst ribAxillarySubclavianBrachiocephalic trunkFigure78
79Module 17.16: Head and neck vessels VeinsExternal jugular vein (cranium, face, lower jaw, and neck on that side)Internal jugular vein (various cranial venous sinuses)Vertebral vein (cervical spinal cord and posterior skull)
80Areas drained by the external and internal jugular veins Dural sinusesdraining the brainTemporalMaxillaryJugular foramenBranches of theExternal JugularFacialOccipitalFigure The external carotid arteries supply the neck, lower jaw, and face, and the internal carotid and vertebral arteries supply the brain, while the external jugular veins drain the regions supplied by the external carotids, and the internal jugular veins drain the brainExternaljugularVertebral veinInternal jugular veinClavicleRight brachiocephalicLeft brachiocephalicAxillaryRightsubclavianSuperiorvena cavaFigure80
81Module Reviewa. Name the arterial structure that contains baroreceptors.b. Identify branches of the external carotid artery.c. Identify the veins that combine to form the brachiocephalic vein.
82Module 17.18: Vessels of the trunk ArteriesSomatic branches of thoracic aortaIntercostal arteries (chest muscles and vertebral column)Superior phrenic artery (superior diaphragm)Visceral branches of thoracic aortaBronchial arteries (lung tissues not involved in gas exchange)Esophageal arteries (esophagus)Mediastinal arteries (tissues of mediastinum)Pericardial arteries (pericardium)
84Module 17.18: Vessels of the trunk Arteries (continued)Major unpaired branches of abdominal aortaCeliac trunk (three branches)Left gastric artery (stomach and inferior esophagus)Splenic artery (spleen and stomach arteries)Common hepatic artery (arteries to liver, stomach, gallbladder, and proximal small intestine)Superior mesenteric artery (pancreas, duodenum, most of large intestine)Inferior mesenteric artery (colon and rectum)
85The branches of the thoracic aorta and the abdominal aorta Aortic archInternal thoracicThoracic aortaVisceral Branches ofthe Thoracic AortaSomatic Branches ofthe Thoracic AortaBronchial arteriesEsophageal arteriesIntercostal arteriesMediastinal arterySuperior phrenic arteryPericardial arteryFigure The regions supplied by the descending aorta are drained by the superior and inferior vena cavaDiaphragmInferior phrenicCeliac trunkAdrenalLeft gastricRenalBranches ofthe celiactrunkSplenicGonadalCommonhepaticLumbarCommon iliacSuperior mesentericAbdomial aortaInferior mesentericFigure85
86Module 17.18: Vessels of the trunk VeinsAzygos and hemiazygos veins (most of thorax)Intercostal veins (chest muscles)Esophageal veins (inferior esophagus)Bronchial veins (passageways of lungs)Mediastinal veins (mediastinal structures)
87Module 17.18: Vessels of the trunk Veins (continued)Major tributaries of inferior vena cavaLumbar veins (lumbar portion of abdomen)Gonadal veins (gonads)Hepatic veins (liver)Renal veins (kidneys)Adrenal veins (adrenal glands)Phrenic veins (diaphragm)
88The major tributaries of the superior and inferior venae cavae BrachiocephalicThe Azygos andHemiazygos VeinsSuperior vena cavaAzygos veinHemiazygos veinInternal thoracicTributaries:Esophageal, bronchial,and mediastinal veinsInferior vena cavaHepaticsIntercostal veinsPhrenicAdrenalRenalGonadalLumbarFigure The regions supplied by the descending aorta are drained by the superior and inferior vena cavaCommon iliacMajor Tributaries of the Inferior Vena Cava• Lumbar veins drain the lumbar portion of the abdomen,including the spinal cord and muscles of the body wall.• Gonadal (ovarian or testicular) veins drain the ovaries oftestes. The right gonadal vein empties into the inferior venacava; the left gonadal vein generally drains into the left renalvein.• Hepatic veins drain the sinusoids of the liver.• Renal veins, the largest tributaries of the inferior venacava, collect blood from the kidneys.• Adrenal veins drain the adrenal glands. In mostindividuals, only the right adrenal vein drains into theinferior vena cava; the left adrenal vein drains into the leftrenal vein.• Phrenic veins drain the diaphragm. Only the right phrenicvein drains into the inferior vena cava; the left drains intothe left renal vein.Figure88
89Module Reviewa. Which vessel collects most of the venous blood inferior to the diaphragm?b. Identify the major tributaries of the inferior vena cava.c. Grace is in an automobile accident, and her celiac trunk is ruptured. Which organs will be affected most directly by this injury?
90Module 17.19: Vessels of the viscera ArteriesBranches of common hepatic arteryHepatic artery proper (liver)Cystic (gallbladder)Gastroduodenal (stomach and duodenum)Right gastric (stomach)Right gastroepiploic (stomach and duodenum)Superior pancreaticoduodenal (duodenum)
91Module 17.19: Vessels of the viscera Arteries (continued)Superior mesenteric arteryInferior pancreaticoduodenal (pancreas and duodenum)Right colic (large intestine)Ileocolic (large intestine)Middle colic (large intestine)Intestinal arteries (small intestine)
92Module 17.19: Vessels of the viscera Arteries (continued)Inferior mesenteric arteryLeft colic (colon)Sigmoid (colon)Rectal (colon)Branches of the splenic arteryLeft gastroepiploic (stomach)Pancreatic (pancreas)
93The locations of the celiac trunk, the superior and inferior mesenteric arteries, and their branches Common hepatic arteryLeft gastric arterySplenic arteryThe celiac trunkBranches of theCommon Hepatic ArteryHepatic artery proper (liver)Cystic (gallbladder)LiverBranches of theSplenic ArteryGastroduodenal (stomachand duodenum)Left gastroepiploic(stomach)Right gastric (stomach)StomachRight gastroepiploic(stomach and duodenum)Pancreatic (pancreas)Superior pancreatico-duodenal (duodenum)SpleenFigure The viscera supplied by the celiac trunk and mesenteric arteries are drained by the tributaries of the hepatic portal veinAscending colonPanceasInferior MesentericArterySuperior MesentericArteryLeft colic (colon)Inferiorpancreaticoduodenal(pancreas andduodenum)Sigmoid (colon)Rectal (rectum)Right colic (largeintestine)Small intestineIleocolic (largeintestine)Sigmoid colonMiddle colic (cut)(large intestine)RectumIntestinal arteries (smallintestine)Figure93
94Module 17.19: Vessels of the viscera VeinsHepatic portal vein tributariesSuperior mesenteric vein and tributariesPancreaticoduodenalMiddle colic (transverse colon)Right colic (ascending colon)Ileocolic (Ileum and ascending colon)Intestinal (small intestine)
95Module 17.19: Vessels of the viscera Veins (continued)Hepatic portal vein tributaries (continued)Splenic vein and tributariesLeft gastroepiploic (stomach)Right gastroepiploic (stomach)PancreaticInferior mesenteric vein and tributariesLeft colic (descending colon)Sigmoid (sigmoid colon)Superior rectal (rectum)
96The veins (and their tributaries) that form the hepatic portal vein Inferior vena cavaLeft gastricHepaticRight gastricLiverStomachSplenic Vein and ItsTributariesCysticHepatic portalLeft gastroepiploic(stomach)SpleenRight gastroepiploic(stomach)Superior MesentericVein and Its TributariesPancreaticPancreasPancreaticoduodenalDescending colonMiddle colic (fromtransverse colon)Inferior MesentericVein and ItsTributariesRight colic (ascendingcolon)Ileocolic (ileum andascending colon)Left colic (descendingcolon)Sigmoid(sigmoid colon)Figure The viscera supplied by the celiac trunk and mesenteric arteries are drained by the tributaries of the hepatic portal veinIntestinal (small intestine)Superior rectal (rectum)Tributaries of the Hepatic Portal Vein• The inferior mesenteric vein collects blood from capillariesalong the inferior portion of the large intestine. It drains theleft colic vein and the superior rectal veins, which collectvenous blood from the descending colon, sigmoid colon,and rectum.• The splenic vein is formed by the union of the inferiormesenteric vein and veins from the spleen, the lateral borderof the stomach (left gastroepiploic vein), and the pancreas(pancreatic veins).• The superior mesenteric vein collects blood from veinsdraining the stomach (right gastroepiploic vein), the smallintestine (intestinal and pancreaticoduodenal veins), andtwo-thirds of the large intestine (ileocolic, right colic, andmiddle colic veins).Figure96
97Module Reviewa. List the unpaired branches of the abdominal aorta that supply blood to the visceral organs.b. Identify the three veins that merge to form the hepatic portal vein.c. Identify two veins that carry blood away from the stomach.
98Module 17.20: Lower limb vessels ArteriesCommon iliac arteryInternal iliac artery (bladder, pelvic walls, external genitalia, medial side of thigh, in females, uterus and vagina)Lateral sacral arteryInternal pudendal arteryObturator arterySuperior gluteal artery
99Module 17.20: Lower limb vessels Arteries (continued)Common iliac artery (continued)External iliac arteryFemoral arteryDeep femoral arteryFemoral circumflex arteries (ventral and lateral skin and deep muscles of thigh)Popliteal artery (posterior knee)Posterior and anterior tibial arteries (leg)Fibular artery (lateral leg)
100Module 17.20: Lower limb vessels Arteries (continued)Arteries of the footDorsalis pedisDorsal archPlantar archMedial plantarLateral plantar
101The arteries that supply the pelvis and lower limb Anterior ViewInternal Iliac and Its BranchesPosterior ViewInternal iliacCommon iliacExternal iliacFemoralRight externaliliacLateral sacralDeep femoralDeep femoralInternal pudendalFemoralcircumflexObturatorFemoral circumflexSuperior glutealFemoralFigure The pelvis and lower limb are supplied by branches of the common iliac artery and drained by tributaries of the common iliac veinDescending genicular arteryPoplitealPoplitealAnterior tibialPosterior tibialAnterior tibialPosterior tibialFibularArteries of the FootFibular (peroneal)Dorsalis pedisMedial plantarLateral plantarDorsal archPlantar archFigure101
102Module 17.20: Lower limb vessels VeinsExternal iliac veins (lower limbs, pelvis, and lower abdomen)Internal iliac veins (pelvic organs)External and internal iliac fuse to form common iliac veins
103The veins that drain the pelvis and lower limb Anterior ViewPosterior ViewCommon iliacExternal iliacInternal iliacGlutealInternal pudendalLateral sacralObturatorFemoralConvergence of the greatsaphenous, the deepfemoral, and the femoralcircumflex veinsFemoral circumflexDeep femoralFemoralFigure The pelvis and lower limb are supplied by branches of the common iliac artery and drained by tributaries of the common iliac veinGreat saphenousFemoralPoplitealSmall saphenousAnterior tibialPosterior tibialFibularDorsal venous archPlantar venousarchDigitalFigure103
104Module Reviewa. Name the first two divisions of the common iliac artery.b. The plantar venous arch carries blood to which three veins?c. A blood clot that blocks the popliteal vein would interfere with blood flow in which other veins?
105CLINICAL MODULE 17.21: Fetal circulation and defects Unique fetal circulation structuresUmbilical arteries (internal iliac arteries to placenta)Umbilical vein (placenta to ductus venosus)Ductus venosus (drains liver and umbilical vein into inferior vena cava)Ductus arteriosus (pulmonary trunk to aorta)Sends blood from right ventricle to systemic circuitForamen ovale (right to left atrium)Has one-way valve to prevent backflow
106The path of blood flow in a full-term fetus before birth Foramen ovaleDuctus arteriosusAortaPlacentaPulmonarytrunkFigure The pattern of blood flow through the fetal heart and the systemic circuit must change at birthLiverInferior vena cavaUmbilical veinDuctus venosusUmbilicalcordUmbilical arteriesFigure106
107CLINICAL MODULE 17.21: Fetal circulation and defects At birth, fetal circulation changes due to activated pulmonary circulationResulting pressure closes foramen ovaleFossa ovalis (shallow depression, adult remnant)Rising oxygen levels cause ductus arteriosus to constrict and closeLigamentum arteriosum (fibrous adult remnant)
108The flow of blood through the heart upon the closing of the ductus arteriosus and foramen ovale at birthDuctus arteriosus(closed)Pulmonary trunkLeft atriumFigure The pattern of blood flow through the fetal heart and the systemic circuit must change at birthForamen ovale(closed)Right atriumLeft ventricleRight ventricleInferiorvena cavaFigure108
109CLINICAL MODULE 17.21: Fetal circulation and defects Congenital cardiac defectsVentricular septal defectsOpenings in interventricular septumPatent foramen ovalePassageway remains openLeft ventricle must work harder to provide adequate systemic flowPatent ductus arteriosusBlood is not adequately oxygenated and skin bluish
110CLINICAL MODULE 17.21 Review a. Describe the pattern of fetal blood flow to and from the placenta.b. Identify the six structures that are necessary in the fetal circulation but cease to function at birth, and describe what becomes of these structures.
111Module 18.4: Coronary circulation Provides cardiac muscle cells with reliable supplies of oxygen and nutrientsDuring maximum exertion, myocardial blood flow may increase to 9× resting levelsBlood flow is continuous but not steadyWith left ventricular relaxation, aorta walls recoil (elastic rebound), which pushes blood into coronary arteries
112Module 18.4: Coronary circulation Coronary arteriesRight coronary artery (right atrium, portions of both ventricles and conduction system of heart)Marginal arteries (right ventricle surface)Posterior interventricular artery (interventricular septum and adjacent ventricular portions)Left coronary artery (left ventricle, left atrium, and interventricular septum)Circumflex artery (from left coronary artery, follows coronary sulcus to meet right coronary artery branches)Anterior interventricular artery (interventricular sulcus)
113Figure 18.4.1-2 The heart has an extensive blood supply The locations of the arterial supply to the heartPulmonarytrunkAorticarchAn anterior view of the coronary arteriesLeftatriumLeft Coronary ArteryLeft coronary arteryCircumflex arteryRightatriumAnteriorinterventriculararteryRight Coronary ArteryRightventricleLeftventricleRight coronary artery in the coronary sulcusMarginal arteriesAnterior viewFigure The heart has an extensive blood supplyArterial anastomosesbetween the anteriorand posteriorinterventricular arteriesThe branches of the coronary arterieson the posterior surface of the heartCircumflex arteryLeftatriumMarginalarteryRightatriumLeftventriclePosteriorinterventriculararteryRightventricleRight coronaryarteryPosterior viewFigure – 2113
114Module 18.4: Coronary circulation Coronary veinsGreat cardiac vein (drains area supplied by anterior interventricular artery, empties into coronary sinus on posterior)Anterior cardiac veins (drains anterior surface of right ventricle, empties into right atrium)
115vessels on the anterior surface of the heart The major collectingvessels on the anteriorsurface of the heartAorticarchLeftatriumRightatriumGreatcardiacveinFigure The heart has an extensive blood supplyAnterior cardiac veinsRightventricleLeftventricleAnterior viewFigure115
116Module 18.4: Coronary circulation Coronary veins (continued)Coronary sinus (expanded vein, empties into right atrium)Posterior cardiac vein (drains area supplied by circumflex artery)Small cardiac vein (drains posterior right atrium and ventricle, empties into coronary sinus)Middle cardiac vein (drains area supplied by posterior interventricular artery, drains into coronary sinus)
117The major collecting vessels on the posterior surface of the heart Greatcardiac veinLeftatriumCoronary sinusFigure The heart has an extensive blood supplyRightatriumLeftventricleSmallcardiacveinPosteriorcardiac veinRightventricleMiddlecardiacveinPosterior viewFigure117
118Module 18.4 Review a. List the arteries and veins of the heart. b. Describe what happens to blood flow during elastic rebound.c. Identify the main vessel that drains blood from the myocardial capillaries.
119Module 18.5: Internal heart anatomy Four chambersTwo atria (left and right separated by interatrial septum)Two ventricles (left and right separated by interventricular septum)Left atrium flows into left ventricleRight atrium flows into right ventricle
120Module 18.5: Internal heart anatomy Right atriumReceives blood from superior and inferior venae cavae and coronary sinusFossa ovalis (remnant of fetal foramen ovale)Pectinate (pectin, comb) muscles (muscular ridges on anterior atrial and auricle walls)Left atriumReceives blood from pulmonary veins
121Module 18.5: Internal heart anatomy Right ventricleReceives blood from right atrium through right atrioventricular (AV) valveAlso known as tricuspid (tri, three)Has three flaps or cusps attached to tendinous connective fibersFibers connect to papillary musclesInnervated to contract through moderator band which keeps “slamming” of AV cuspsPrevents backflow of blood to atrium during ventricular contraction
122Module 18.5: Internal heart anatomy Left ventricleReceives blood from left atrium through right atrioventricular valveAlso known as bicuspid and mitral (mitre, bishop’s hat) valvePrevents backflow of blood to atrium during ventricular contractionHas paired flaps or cuspsTrabeculae carneae (carneus, fleshy)Muscular ridges on ventricular wallsAortic valveAllows blood to exit left ventricle and enter aorta
123The internal anatomy of the heart and the direction of blood flow betweenthe chambersAscendingaortaPulmonarytrunkSuperiorvena cavaLeft AtriumRight AtriumAortic archReceives blood fromthe pulmonary veinsReceives blood from the superiorand inferior venae cavae and fromthe cardiac veins through thecoronary sinusLeft pulmonary veinsFossa ovalisPectinate muscles on the innersurface of the auricleFigure Internal valves control the direction of blood flow between the heart chambersOpening of the coronary sinusLeft VentricleRight VentricleThick wall of left ventricleRight atrioventricular (AV)valve (tricuspid valve)Left atrioventricular (AV)valve (bicuspid valve)Chordae tendineaeInferiorvena cavaTrabeculae carneaePapillary muscleInterventricularseptumPulmonary valve (pulmonarysemilunar valve)Aortic valveModeratorbandFigure123
124Module 18.5: Internal heart anatomy Ventricular comparisonsRight ventricle has relatively thin wallVentricle only pushes blood to nearby pulmonary circuitWhen it contracts, it squeezes against left ventricle wall forcing blood out pulmonary trunkLeft ventricle has extremely thick wall and is round in cross sectionVentricle must develop 4–6× as much pressure as right to push blood around systemic circuitWhen it contractsDiameter of chamber decreasesDistance between base and apex decreases
125interventricular sulcus A sectional view of the heart showingthe thicknesses of the ventricle wallsand the shapes of the ventricularchambersPosteriorinterventricular sulcusThe left ventricle hasan extremely thickmuscular wall and isround in cross section.Figure Internal valves control the direction of blood flow between the heart chambersThe relatively thin wallof the right ventricleresembles a pouchattached to the massivewall of the left ventricleFat in anteriorinterventricular sulcusFigure125
126Dilated (relaxed) Contracted The changes in ventricle shape during ventricularcontractionLeftventricleRightventricleDilated (relaxed)Figure Internal valves control the direction of blood flow between the heart chambersContraction of left ventricledecreases the diameter of theventricular chamber and reducesthe distance between the baseand apexContraction of rightventricle squeezesblood against the thickwall of the left ventricle.ContractedFigure126
127Module 18.5 Reviewa. Damage to the semilunar valves on the right side of the heart would affect blood flow to which vessel?b. What prevents the AV valves from swinging into the atria?c. Why is the left ventricle more muscular than the right ventricle?
128Module 18.6: Heart valves Semilunar (half-moon shaped) valves Aortic and pulmonary semilunar valvesAllow blood to exit ventricles and enter aorta or pulmonary trunkDo not require muscular braces because cusps are stableAll three symmetrical cusps support each other
129Module 18.6: Heart valvesValve action during atrial contraction and ventricular relaxationAV valvesOpenBlood pressure from contracting atria pushes cusps apartChordae tendineae are loose, offering no resistanceSemilunar valves (aortic and pulmonary)ClosedLittle pressure from ventriclesBlood pressure from aorta and pulmonary arteries keep closed
130The positions of the valves and associated structures when the ventricles are relaxedPulmonaryveinsLeftatriumRightventricleAortic valve (closed)Figure When the heart beats, the AV valves close before the semilunar valves open, and the semilunar valves close before the AV valves openLeft AV (bicuspid)valve (open)Chordae tendineae(loose)Left ventricle(dilated)Papillary muscles(relaxed)Right AV (tricuspid)valve (open)KEYOxygenatedbloodAortic valve (closed)Superior viewof cardiac valvesPulmonary valve (closed)DeoxygenatedbloodFigure130
131Module 18.6: Heart valvesValve action during atrial relaxation and ventricular contractionAV valvesClosedBlood pressure from contracting ventricles pushes cusps togetherPapillary muscles tensing prevent cusps from swinging into atria (would allow backflow or regurgitation)Semilunar valves (aortic and pulmonary)OpenHigh blood pressure from ventricles overcome blood pressures from aorta and pulmonary arteriesAnimation: The Heart: Valves
132KEYAortic sinusOxygenatedbloodThe positions of the valves and associatedstructures when the ventricles contractDeoxygenatedbloodAortaLeftatriumAortic valve (open)Chordae tendineae(tense)Left AV (bicuspid)valve (closed)Figure When the heart beats, the AV valves close before the semilunar valves open, and the semilunar valves close before the AV valves openLeft ventricle(contracted)Papillary muscles(contracted)Right AV (tricuspid)valve (closed)Ventricular contractionAortic valve (open)Superior viewof cardiac valvesPulmonary valve (open)Frontal section throughleft atrium and ventricleFigure132
133Module 18.6: Heart valves Cardiac skeleton Flexible connective tissues in which all valves are encircled and supportedAlso surrounds aorta and pulmonary trunkSeparates atrial and ventricular myocardiumContains dense bands of tough elastic tissue
134A superior view of the heart showing the cardiac skeleton Figure When the heart beats, the AV valves close before the semilunar valves open, and the semilunar valves close before the AV valves openFigure134
135Module 18.6 Review a. Define cardiac regurgitation. b. Compare the structure of the tricuspid valve with that of the pulmonary valve.c. What do semilunar valves prevent?
136Section 2: The Cardiac Cycle Period from one heartbeat to the beginning of nextAlternating periods of contraction (systole) and relaxation (diastole)Atria contract as a pair firstAs ventricles are relaxed and fillingVentricles contract as a pair nextAs atria are relaxed and fillingCardiac pacemaker system coordinatesTypical cardiac cycle lasts 800 msec
137A cardiac cycle: a heartbeat (contraction) followed by a brief period of relaxationFigure 18 Section 2 The Cardiac CycleRelaxationContractionFigure 18 Section137
138The sequence of events during a single heartbeat Figure 18 Section 2 The Cardiac CycleRelaxationAtria contractVentricles contractRelaxationFigure 18 Section138
139Cardiac cycle The two phases of the cardiac cycle for a given chamber in the heart: systole(contraction) and diastole (relaxation)Startmsec800msec100msecAtrialsystolediastolesystoleCardiaccycleFigure 18 Section 2 The Cardiac CycleVentricularVentricularAtrialdiastole370msecFigure 18 Section139
140Module 18.8: Cardiac cycle phases Steps of cardiac cycle (for 75 bpm heart rate)When cycle begins, all four chambers are relaxedAtrial systole (100 msec)Contracting atria fill relaxed ventricles with bloodAtrial diastole (270 msec)Concurrent with ventricular systole (2 phases)Ventricular systole – first phaseContracting ventricles push AV valves open but not enough pressure to open semilunar valves= Isovolumetric contraction
141Module 18.8: Cardiac cycle phases Steps of cardiac cycle (continued)Ventricular systole – second phaseAs ventricular pressure rises, semilunar valves open and blood leaves ventricle (= ventricular ejection)Ventricular diastole – earlyVentricles relax and blood pressure in them drops allowing closure of semilunar valvesIsovolumetric relaxation occurs with AV valves still closedVentricular diastole – lateAll chambers relaxedVentricles fill passively to roughly 70%Animation: The Heart: Cardiac Cycle
142The phases of the cardiac cycle for a heart rate of 75 beats per minute StartWhen the cardiac cyclebegins, all four chambersare relaxed, and theventricles are partiallyfilled with blood.During atrial systole, theatria contract, completelyfilling the relaxedventricles with blood.Atrial systole lasts100 msec.Ventricular diastole lasts 530msec (the 430 msec remaining inthis cardiac cycle, plus the first100 msec of the next). Throughoutthe rest of this cardiac cycle,filling occurs passively, and boththe atria and the ventricles arerelaxed. The next cardiac cyclebegins with atrial systole and thecompletion of ventricular filling.Atrial systoleends and atrialdiastole beginsand continues untilthe start of the nextcardiac cycle.As atrial systole ends,ventricular systole begins.This period, which lasts270 msec, can be dividedinto two phases.msec800msec100msecAtrialsystoleVentricular systole—first phase: Ventricularcontraction pushes theAV valves closed butdoes not create enoughpressure to open thesemilunar valves. This isknown as the period ofisovolumetriccontraction.Figure The cardiac cycle creates pressure gradients that maintain blood flowdiastoleCardiaccyclesystoleVentricular diastole—late: All chambers arerelaxed. The ventriclesfill passively to roughly70% of their finalvolume.VentricularVentricularAtrialdiastoleVentricular systole—second phase: Asventricular pressure risesand exceeds pressure inthe arteries, the semilunarvalves open and bloodis forced out of theventricle. This isknown as the periodof ventricularejection.370msecBlood flows into therelaxed atria but theAV valves remainclosed. This is knownas the period ofisovolumetricrelaxation.Ventricular diastole—early: As the ventriclesrelax, the pressure in themdrops; blood flows backagainst the cusps of thesemilunar valves and forcesthem closed.Figure142
143The pressure changes within the aorta, left atrium, and left ventricle during the cardiac cycle ATRIALDIASTOLEATRIALSYSTOLEATRIALSYSTOLEATRIAL DIASTOLEVENTRICULARDIASTOLEVENTRICULARSYSTOLEVENTRICULAR DIASTOLE120Aortic valve closes.Aortic valveopens.90AortaDicrotic notchKEYAtrial contraction begins.Pressure (mm Hg)Atria eject blood into ventricles.60Atrial systole ends; AV valves close.LeftventricleIsovolumetric contraction.Figure The cardiac cycle creates pressure gradients that maintain blood flowVentricular ejection occurs.Semilunar valves close.30Left atriumLeft AVvalve closes.Isovolumetric relaxation occurs.Left AV valve opens.AV valves open; passive ventricularfilling occurs.100200300400500600700800Time (msec)The correspondence of the heart sounds with events during the cardiac cycleS1S2S4S3S4Heart sounds“Lubb”“Dubb”Figure143
144Module 18.8: Cardiac cycle phases Heart soundsS1 (known as “lubb”)Start of ventricular contraction and closure of AV valvesS2 (known as “dupp”)Closure of semilunar valvesS3 and S4Very faint and rarely heard in adultsS3 (blood flowing into ventricles)S4 (atrial contraction)
145Module 18.8 Reviewa. Provide the alternate terms for heart contraction and heart relaxation.b. List the phases of the cardiac cycle.c. Is the heart always pumping blood when pressure in the left ventricle is rising? Explain.
146Module 18.9: Cardiac output and conduction system Network of specialized cardiac muscle cellsResponsible for initiating and distributing stimulus to contractCan do so on their own (= automaticity)ComponentsSinoatrial (SA) nodeEmbedded in posterior wall of right atriumImpulse generated by this pacemaker is distributed through other componentsInternodal pathwaysDistribute signal to atria on way to ventricles
147Module 18.9: Cardiac output and conduction system Conduction system (continued)Atrioventricular (AV) nodeLocated at junction of atria and ventriclesAlso contains pacemaker cellsIf SA node damaged, can maintain heart rate at 40–60 bpmCan conduct impulses at maximum rate of 230/min= Maximum heart rateAV bundle and branchesLocated in interventricular septumNormally only electrical connection between atria and ventriclesBranches relay signal to ventricles toward heart apex
148Module 18.9: Cardiac output and conduction system Conduction system (continued)Purkinje fibersLarge-diameter conducting cellsAs fast as small myelinated axonsFinal part of conduction system that triggers ventricular systoleAnimation: The Heart: Conduction System
149The components of the conducting system and their specific functions Each heartbeat begins with an actionpotential generated at the sinoatrial(sī-nō-Ā-trē-al) node, or simply theSA node. The SA node is embeddedin the posterior wall of the rightatrium, near the entrance of thesuperior vena cava. The electricalimpulse generated by this cardiacpacemaker is then distributed byother cells of the conducting system.Purkinje fibers are large-diameterconducting cells that propagate actionpotentials very rapidly—as fast as smallmyelinated axons. Purkinje cells are thefinal link in the distribution network, andthey are responsible for the depolarizationof the ventricular myocardial cells thattriggers ventricular systole.In the atria, conducting cells arefound in internodal pathways,which distribute the contractilestimulus to atrial muscle cells as theimpulse travels toward the ventricles.Figure The heart rate, a key factor in cardiac output, is established by the SA node and distributed by the conducting systemThe AV node delivers the stimulusto the AV bundle, located within theinterventricular septum. The AV bundle isnormally the only electrical connectionbetween the atria and the ventricles.ModeratorbandThe AV bundle leads to the right and leftbundle branches. The left bundlebranch, which supplies the massive leftventricle, is much larger than the rightbundle branch. Both branches extendtoward the apex of the heart, turn, andfan out deep to the endocardial surface.The atrioventricular (AV) node is located at the junctionbetween the atria and ventricles. The AV node also containspacemaker cells, but they do not ordinarily affect the heartrate. However, if the SA node or internodal pathways aredamaged, the heart will continue to beat because in theabsence of commands from the SA node, the AV node willgenerate impulses at a rate of 40–60 beats per minute.Figure149
150The distribution of the contractile stimulus, andhow the conducting systemcoordinates the contractionsof the cardiac cycleAn action potential isgenerated at the SAnode, and atrialactivation begins.SA nodeTime = 0The stimulus spreadsacross the atrialsurfaces by cell-to-cellcontact within theinternodal pathwaysand soon reaches theAV node.AV nodeElapsed time = 50 msecA 100-msec delayoccurs at the AVnode. During thisdelay, atrialcontraction begins.Figure The heart rate, a key factor in cardiac output, is established by the SA node and distributed by the conducting systemAVbundleBundlebranchesElapsed time = 150 msecAs atrial contractioncontinues, the impulsetravels along theinterventricular septumwithin the AV bundle andthe bundle branches tothe Purkinje fibers and, viathe moderator band, tothe papillary muscles ofthe right ventricle.ModeratorbandElapsed time = 175 msecThe impulse is distributedby Purkinje fibers andrelayed throughout theventricular myocardium.Atrial contraction iscompleted, andventricular contractionbegins.Purkinje fibersElapsed time = 225 msecFigure150
151Module 18.9 Review a. Define automaticity. b. If the cells of the SA node failed to function, how would the heart rate be affected?c. Why is it important for impulses from the atria to be delayed at the AV node before they pass into the ventricles?
152Module 18.11: Autonomic control of heart function Pacemaker cells in the SA and AV nodes cannot maintain a stable resting potentialAlways gradual depolarization leading to threshold (= prepotential or pacemaker potential)Fastest rate at SA node (80–100 bpm)Brings other conduction system components to threshold
153Heart rate under three conditions: at rest, under parasympathetic stimulation, and under sympathetic stimulationA prepotential or pacemaker potentialin a heart at restFigure The intrinsic heart rate can be altered by autonomic activityNormal (resting)Prepotential(spontaneousdepolarization)+20Membranepotential(mV)–30Threshold–60Heart rate: 75 bpm0.81.62.4Time (sec)Figure153
154Module 18.11: Autonomic control of heart function Autonomic changes to intrinsic heart rateFactors that change rate of depolarization and repolarization will change time to thresholdLeads to change in heart rateBradycardia (heart rate slower than normal, <60 bpm)Tachycardia (heart rate faster than normal, >100 bpm)Parasympathetic stimulationBinding of ACh from parasympathetic neurons opens K+ channels, slows heart rateSlows rate of depolarizationExtends duration in repolarization
155Module 18.11: Autonomic control of heart function Autonomic changes to intrinsic heart rate (continued)Sympathetic stimulationBinding of noepinephrine to beta-1 receptors leads to opening of ion channels, and increases heart rateIncreases rate of depolarizationShortens duration in repolarization
156Parasympathetic stimulation Heart rate under three conditions: at rest, under parasympatheticstimulation, and under sympathetic stimulationA prepotential or pacemaker potentialin a heart at restIncreased heart rate resulting whenACh released by parasympatheticneurons opens chemically gated K+channels, thereby slowing the rateof spontaneous depolarizationFigure The intrinsic heart rate can be altered by autonomic activityParasympathetic stimulation+20Membranepotential(mV)–30ThresholdHyperpolarization–60Heart rate: 40 bpmSlower depolarization0.81.62.4Time (sec)Figure156
157CLINICAL MODULE 18.14: Electrocardiograms (ECG) Electrocardiograms record electrical activities of heart from body surface through timeCan be used to assess performance of:NodesConduction systemContractile componentsAppearance varies with placement and number of electrodes or leads
158An electrocardiogram: a standard placement of leads and the tracing that resultsOne of the standardconfigurations for theplacement of leads foran ECG800 msecFigure Normal and abnormal cardiac activity can be detected in an electrocardiogramThe features of a typical electrocardiogramP waveQRS complexT wave+1R+0.5PTMillivoltsQS–0.5P–R intervalQ–T intervalFigure158
159CLINICAL MODULE 18.14: Electrocardiograms (ECG) Typical ECG featuresP wave (atrial depolarization)Atria begin contracting ~25 msec after P wave startQRS complex (atrial repolarization and ventricular depolarization)Larger wave due to larger ventricles added to atrial activityVentricles begin contracting shortly after R wave peakT wave (ventricular repolarization)
160CLINICAL MODULE 18.14: Electrocardiograms (ECG) Typical ECG features (continued)P-R interval (start of atrial depolarization to start of ventricular depolarization)>200 msec may indicate damage to conducting pathways or AV nodeQ-T interval (time for ventricles to undergo a single cycle)Starts at end of P-R interval to end of T wave
161Module 18.16: Blood pressure and flow Blood flow (F) is directly proportional to blood pressureIncreased pressure = increased flowThe pressure gradient (difference from one end of vessel to other) is more importantLarge gradient from aorta to capillariesSmaller, more numerous vessels produce more resistance, reducing pressure and flowAt aorta: 2.5 cm diameter and 100 mm Hg pressureAt capillaries: 8 µm diameter and 25 mm Hg pressure
162Module 18.16: Blood pressure and flow Arterial pressure is variableRising during ventricular systole (systolic pressure)Declining during ventricular diastole (diastolic pressure)Commonly written with a “/” between pressuresExample: 120/90Pulse pressure (difference between systolic and diastolic)Example: 120 – 90 = 30 mm HgMean arterial pressure (MAP)Adding 1/3 of pulse pressure to diastolic pressureExample: 90 + (120 – 90)/3 = 100 mm Hg
163The calculation of mean arterial pressure SystolicPulse pressure,the differencebetween systolicand diastolicpressures120Mean arterial pressure(MAP), the sum of thediastolic pressure andone-third of the pulsepressure10080Here, MAP isFigure Blood flow is determined by the interplay between arterial pressure and peripheral resistanceDiastolic90 + (120 – 90 )/360or= 100 mm Hgmm Hg4020AortaElasticarteriesMusculararteriesArteriolesCapillariesVenulesMedium-sized veinsLargeveinsVenaecavaeFigure163
164Module 18.16: Blood pressure and flow Capillary exchangeInvolves:FiltrationCapillary hydrostatic pressure (CHP) provides driving forceWater and small solutes leave capillariesLarger molecules (like plasma proteins) remain in bloodDiffusionOsmosis
165The effect of capillary hydrostatic pressure on water and small solutesCapillaryhydrostaticpressure(CHP)Amino acidBlood proteinGlucoseIonsInterstitial fluidFigure Blood flow is determined by the interplay between arterial pressure and peripheral resistanceSmall solutesHydrogen bondWater moleculeEndothelialcell 1Endothelialcell 2Figure165
166Module Reviewa. Define blood flow, and describe its relationship to blood pressure and peripheral resistance.b. In a healthy individual, where is blood pressure greater: in the aorta or in the inferior vena cava? Explain.c. For an individual with a blood pressure of 125/70, calculate the mean arterial pressure (MAP).