Chapter 19



Chapter 19 BloodAn Introduction to Blood and the Cardiovascular SystemLearning Outcomes19-1Describe the components and major functions of blood, identify blood collection sites, and list the physical characteristics of blood.19-2Specify the composition and functions of plasma.19-3List the characteristics and functions of red blood cells, describe the structure and functions of hemoglobin, describe how red blood cell components are recycled, and explain erythropoiesis.An Introduction to Blood and the Cardiovascular SystemLearning Outcomes19-4Explain the importance of blood typing, and the basis for ABO and Rh incompatibilities.19-5Categorize white blood cell types based on their structures and functions, and discuss the factors that regulate the production of each type.19-6Describe the structure, function, and production of platelets.19-7Discuss the mechanisms that control blood loss after an injury, and describe the reaction sequences responsible for blood clotting.An Introduction to Blood and the Cardiovascular SystemThe Cardiovascular System consists of:A pump (the heart)A conducting system (blood vessels)A fluid medium (blood) Is specialized fluid of connective tissueContains cells suspended in a fluid matrixAn Introduction to Blood and the Cardiovascular SystemBlood Transports materials to and from cellsOxygen and carbon dioxideNutrientsHormonesImmune system components Waste products19-1 Physical Characteristics of BloodImportant Functions of BloodTransportation of dissolved substancesRegulation of pH and ionsRestriction of fluid losses at injury sitesDefense against toxins and pathogensStabilization of body temperature19-1 Physical Characteristics of BloodWhole Blood Plasma Fluid consisting of:WaterDissolved plasma proteinsOther solutes Formed elements All cells and solids19-1 Physical Characteristics of BloodThree Types of Formed Elements Red blood cells (RBCs) or erythrocytesTransport oxygen White blood cells (WBCs) or leukocytesPart of the immune system PlateletsCell fragments involved in clotting19-1 Physical Characteristics of BloodHemopoiesisProcess of producing formed elementsBy myeloid and lymphoid stem cells FractionationProcess of separating whole blood for clinical analysisInto plasma and formed elements19-1 Physical Characteristics of BloodThree General Characteristics of Blood38C (100.4F) is normal temperatureHigh viscositySlightly alkaline pH (7.35–7.45)19-1 Physical Characteristics of BloodCharacteristics of BloodBlood volume (liters) 7 percent of body weight (kilograms)Adult male: 5–6 litersAdult female: 4–5 liters19-2 PlasmaThe Composition of PlasmaMakes up 50–60 percent of blood volumeMore than 90 percent of plasma is waterExtracellular fluidsInterstitial fluid (IF) and plasmaMaterials plasma and IF exchange across capillary wallsWaterIonsSmall solutes19-2 PlasmaPlasma ProteinsAlbumins (60 percent)Globulins (35 percent) Fibrinogen (4 percent)19-2 PlasmaAlbumins (60 percent)Transport substances such as fatty acids, thyroid hormones, and steroid hormonesGlobulins (35 percent) Antibodies, also called immunoglobulinsTransport globulins (small molecules): hormone-binding proteins, metalloproteins, apolipoproteins (lipoproteins), and steroid-binding proteinsFibrinogen (4 percent)Molecules that form clots and produce long, insoluble strands of fibrin19-2 PlasmaSerumLiquid part of a blood sampleIn which dissolved fibrinogen converts to solid fibrin19-2 PlasmaOther Plasma Proteins1 percent of plasmaChanging quantities of specialized plasma proteins Peptide hormones normally present in circulating bloodInsulin, prolactin (PRL), and the glycoproteins thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH)19-2 PlasmaOrigins of Plasma ProteinsMore than 90 percent made in liverAntibodies made by plasma cellsPeptide hormones made by endocrine organs19-3 Red Blood CellsRed blood cells (RBCs) Make up 99.9 percent of blood’s formed elementsHemoglobinThe red pigment that gives whole blood its colorBinds and transports oxygen and carbon dioxide19-3 Red Blood CellsAbundance of RBCsRed blood cell count – the number of RBCs in 1 microliter of whole blood Male: 4.5–6.3 millionFemale: 4.2–5.5 million19-3 Red Blood CellsAbundance of RBCsHematocrit – (packed cell volume, PCV) percentage of RBCs in centrifuged whole bloodMale: 40–54Female: 37–4719-3 Red Blood CellsStructure of RBCsSmall and highly specialized discsThin in middle and thicker at edge19-3 Red Blood CellsThree Important Effects of RBC Shape on Function High surface-to-volume ratioQuickly absorbs and releases oxygenDiscs form stacks called rouleauxSmooth the flow through narrow blood vesselsDiscs bend and flex entering small capillaries7.8-?m RBC passes through 4-?m capillary19-3 Red Blood CellsLife Span of RBCsLack nuclei, mitochondria, and ribosomesMeans no repair and anaerobic metabolismLive about 120 days19-3 Red Blood CellsHemoglobin (Hb) Protein molecule that transports respiratory gasesNormal hemoglobin (adult male)14–18 g/dL whole bloodNormal hemoglobin (adult female)12–16 g/dL whole blood19-3 Red Blood CellsHemoglobin StructureComplex quaternary structureFour globular protein subunitsEach with one molecule of hemeEach heme contains one iron ion19-3 Red Blood CellsHemoglobin StructureIron ions Associate easily with oxygen (oxyhemoglobin, HbO2) Dissociate easily from oxygen (deoxyhemoglobin) 19-3 Red Blood CellsFetal HemoglobinStrong form of hemoglobin found in embryosTakes oxygen from mother’s hemoglobin19-3 Red Blood CellsHemoglobin FunctionCarries oxygenWith low oxygen (peripheral capillaries):Hemoglobin releases oxygenBinds carbon dioxide and carries it to lungsForms carbaminohemoglobin19-3 Red Blood CellsRBC Formation and Turnover1 percent of circulating RBCs wear out per day About 3 million new RBCs per secondHemoglobin Conversion and RecyclingMacrophages of liver, spleen, and bone marrowMonitor RBCsEngulf RBCs before membranes rupture (hemolyze)19-3 Red Blood CellsHemoglobin Conversion and RecyclingPhagocytes break hemoglobin into components Globular proteins to amino acidsHeme to biliverdin Iron19-3 Red Blood CellsHemoglobin Conversion and RecyclingHemoglobinuriaHemoglobin breakdown products in urine due to excess hemolysis in bloodstreamHematuriaWhole red blood cells in urine due to kidney or tissue damage19-3 Red Blood CellsBreakdown of BiliverdinBiliverdin (green) is converted to bilirubin (yellow)Bilirubin Is excreted by liver (bile)Jaundice is caused by bilirubin buildupConverted by intestinal bacteria to urobilins and stercobilins19-3 Red Blood CellsIron RecyclingIron removed from heme leaving biliverdinTo transport proteins (transferrin) To storage proteins (ferritin and hemosiderin)19-3 Red Blood CellsRBC ProductionErythropoiesisOccurs only in myeloid tissue (red bone marrow) in adultsStem cells mature to become RBCs19-3 Red Blood CellsHemocytoblastsStem cells in myeloid tissue divide to produce: Myeloid stem cells become RBCs, some WBCs Lymphoid stem cells become lymphocytes 19-3 Red Blood CellsStages of RBC MaturationMyeloid stem cell ProerythroblastErythroblastsReticulocyteMature RBC 19-3 Red Blood CellsRegulation of ErythropoiesisBuilding red blood cells requires:Amino acidsIronVitamins B12, B6, and folic acidPernicious anemiaLow RBC production Due to unavailability of vitamin B1219-3 Red Blood CellsStimulating HormonesErythropoietin (EPO) Also called erythropoiesis-stimulating hormoneSecreted when oxygen in peripheral tissues is low (hypoxia) Due to disease or high altitude19-4 Blood TypingSurface AntigensAre cell surface proteins that identify cells to immune system Normal cells are ignored and foreign cells attackedBlood TypesAre genetically determinedBy presence or absence of RBC surface antigens A, B, Rh (or D) 19-4 Blood TypingFour Basic Blood Types A (surface antigen A) B (surface antigen B) AB (antigens A and B) O (neither A nor B)19-4 Blood TypingAgglutinogensAntigens on surface of RBCsScreened by immune system Plasma antibodies attack and agglutinate (clump) foreign antigens 19-4 Blood TypingBlood Plasma AntibodiesType AType B antibodiesType BType A antibodiesType OBoth A and B antibodiesType ABNeither A nor B antibodies19-4 Blood TypingThe Rh FactorAlso called D antigenEither Rh positive (Rh+) or Rh negative (Rh–) Only sensitized Rh– blood has anti-Rh antibodies 19-4 Blood TypingCross-Reactions in TransfusionsAlso called transfusion reactionPlasma antibody meets its specific surface antigenBlood will agglutinate and hemolyzeOccur if donor and recipient blood types not compatible19-4 Blood TypingTesting for Transfusion CompatibilityPerformed on donor and recipient blood for compatibilityWithout cross-match, type O– is universal donor19-5 White Blood CellsWhite Blood Cells (WBCs)Also called leukocytes Do not have hemoglobinHave nuclei and other organelles WBC functionsDefend against pathogensRemove toxins and wastesAttack abnormal cells19-5 White Blood CellsWBC Circulation and MovementMost WBCs in:Connective tissue properLymphatic system organs Small numbers in blood5000 to 10,000 per microliter19-5 White Blood CellsWBC Circulation and MovementFour Characteristics of Circulating WBCsCan migrate out of bloodstreamHave amoeboid movementAttracted to chemical stimuli (positive chemotaxis)Some are phagocyticNeutrophils, eosinophils, and monocytes19-5 White Blood CellsTypes of WBCsNeutrophilsEosinophilsBasophilsMonocytesLymphocytes19-5 White Blood CellsNeutrophils Also called polymorphonuclear leukocytes 50–70 percent of circulating WBCsPale cytoplasm granules with:Lysosomal enzymesBactericides (hydrogen peroxide and superoxide)19-5 White Blood CellsNeutrophil Action Very active, first to attack bacteriaEngulf and digest pathogensDegranulationRemoving granules from cytoplasmDefensins (peptides from lysosomes) attack pathogen membranesRelease prostaglandins and leukotrienesForm pus19-5 White Blood CellsEosinophils (Acidophils)2–4 percent of circulating WBCsAttack large parasitesExcrete toxic compoundsNitric oxideCytotoxic enzymesAre sensitive to allergens Control inflammation with enzymes that counteract inflammatory effects of neutrophils and mast cells19-5 White Blood CellsBasophilsAre less than 1 percent of circulating WBCsAccumulate in damaged tissueRelease histamineDilates blood vesselsRelease heparinPrevents blood clotting 19-5 White Blood CellsMonocytes 2–8 percent of circulating WBCsAre large and sphericalEnter peripheral tissues and become macrophagesEngulf large particles and pathogensSecrete substances that attract immune system cells and fibroblasts to injured area19-5 White Blood CellsLymphocytes20–40 percent of circulating WBCsAre larger than RBCsMigrate in and out of bloodMostly in connective tissues and lymphoid organsAre part of the body’s specific defense system19-5 White Blood CellsThree Classes of Lymphocytes T cellsCell-mediated immunityAttack foreign cells directly19-5 White Blood CellsThree Classes of Lymphocytes B cellsHumoral immunityDifferentiate into plasma cells Synthesize antibodies Natural killer (NK) cellsDetect and destroy abnormal tissue cells (cancers)19-5 White Blood CellsThe Differential Count and Changes in WBC ProfilesDetects changes in WBC populationsInfections, inflammation, and allergic reactions19-5 White Blood CellsWBC DisordersLeukopeniaAbnormally low WBC countLeukocytosisAbnormally high WBC countLeukemiaExtremely high WBC count19-5 White Blood CellsWBC ProductionAll blood cells originate from hemocytoblastsWhich produce progenitor cells called myeloid stem cells and lymphoid stem cells19-5 White Blood CellsWBC ProductionMyeloid stem cells Produce all WBCs except lymphocytesLymphoid stem cellsLymphopoiesis – the production of lymphocytes19-5 White Blood CellsWBC DevelopmentWBCs, except monocytesDevelop in bone marrowMonocytesDevelop into macrophages in peripheral tissues19-5 White Blood CellsRegulation of WBC ProductionColony-stimulating factors (CSFs)Hormones that regulate blood cell populationsM-CSF stimulates monocyte productionG-CSF stimulates production of granulocytes (neutrophils, eosinophils, and basophils) GM-CSF stimulates granulocyte and monocyte productionMulti-CSF accelerates production of granulocytes, monocytes, platelets, and RBCs19-6 PlateletsPlatelets Cell fragments involved in human clotting systemNonmammalian vertebrates have thrombocytes (nucleated cells) Circulate for 9–12 daysAre removed by spleen2/3 are reserved for emergencies19-6 PlateletsPlatelet Counts150,000 to 500,000 per microliter ThrombocytopeniaAbnormally low platelet countThrombocytosisAbnormally high platelet count19-6 PlateletsThree Functions of PlateletsRelease important clotting chemicalsTemporarily patch damaged vessel wallsReduce size of a break in vessel wall19-6 PlateletsPlatelet Production Also called thrombocytopoiesisOccurs in bone marrowMegakaryocytesGiant cells in bone marrowManufacture platelets from cytoplasm19-6 PlateletsPlatelet Production Hormonal controls Thrombopoietin (TPO) Interleukin-6 (IL-6) Multi-CSF19-7 HemostasisHemostasis Is the cessation of bleedingConsists of three phases Vascular phase Platelet phase Coagulation phase19-7 HemostasisThe Vascular PhaseA cut triggers vascular spasm that lasts 30 minutesThree Steps of the Vascular PhaseEndothelial cells contract and expose basement membrane to bloodstream19-7 HemostasisThree Steps of the Vascular PhaseEndothelial cellsRelease chemical factors ADP, tissue factor, and prostacyclinRelease local hormones, endothelinsStimulate smooth muscle contraction and cell divisionEndothelial plasma membranes become “sticky”Seal off blood flow19-7 HemostasisThe Platelet PhaseBegins within 15 seconds after injuryPlatelet adhesion (attachment)To sticky endothelial surfacesTo basement membranesTo exposed collagen fibers Platelet aggregation (stick together)Forms platelet plug that closes small breaks19-7 HemostasisPlatelet PhaseActivated platelets release clotting compounds Adenosine diphosphate (ADP) Thromboxane A2 and serotonin Clotting factors Platelet-derived growth factor (PDGF) Calcium ions 19-7 HemostasisFactors That Limit the Growth of the Platelet Plug Prostacyclin, released by endothelial cells, inhibits platelet aggregation Inhibitory compounds released by other WBCs Circulating enzymes break down ADP Negative (inhibitory) feedback from serotonin Development of blood clot isolates area19-7 HemostasisThe Coagulation PhaseBegins 30 seconds or more after the injuryBlood clotting (coagulation)Cascade reactions Chain reactions of enzymes and proenzymesForm three pathwaysConvert circulating fibrinogen into insoluble fibrin19-7 HemostasisClotting Factors Also called procoagulants Proteins or ions in plasmaRequired for normal clotting19-7 HemostasisThree Coagulation Pathways Extrinsic pathway Intrinsic pathway Common pathway19-7 HemostasisThe Extrinsic Pathway Begins in the vessel wallOutside bloodstreamDamaged cells release tissue factor (TF) TF + other compounds = enzyme complexActivates Factor X 19-7 HemostasisThe Intrinsic Pathway Begins with circulating proenzymesWithin bloodstreamActivation of enzymes by collagen Platelets release factors (e.g., PF-3) Series of reactions activates Factor X19-7 HemostasisThe Common Pathway Where intrinsic and extrinsic pathways convergeForms complex prothrombin activatorConverts prothrombin to thrombinThrombin converts fibrinogen to fibrin19-7 HemostasisFeedback Control of Blood ClottingStimulates formation of tissue factorStimulates release of PF-3Forms positive feedback loop (intrinsic and extrinsic)Accelerates clotting19-7 HemostasisFeedback Control of Blood ClottingAnticoagulants (plasma proteins)Antithrombin-IIIAlpha-2-macroglobulinHeparinAspirinProtein C (activated by thrombomodulin)Prostacyclin19-7 HemostasisCalcium Ions, Vitamin K, and Blood ClottingCalcium ions (Ca2+) and vitamin K are both essential to the clotting process19-7 HemostasisClot RetractionPulls torn edges of vessel closer togetherReducing residual bleeding and stabilizing injury siteReduces size of damaged areaMaking it easier for fibroblasts, smooth muscle cells, and endothelial cells to complete repairs19-7 HemostasisFibrinolysisSlow process of dissolving clotThrombin and tissue plasminogen activator (t-PA) Activate plasminogen Plasminogen produces plasminDigests fibrin strands ................
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