Chapter 19: BloodBiology 141 A&PBrashear-Kaulfers

What are the components of the cardiovascular system, and their major functions?

The Cardiovascular SystemA circulating transport system:a pump (the heart)a conducting system (blood vessels)a fluid medium (blood)

Functions of the Cardiovascular SystemTo transport materials to and from cells:oxygen and carbon dioxidenutrientshormonesimmune system components waste products

What are the important components and major functions of blood?

BloodIs specialized fluid of connective tissue -contains cells suspended in a fluid matrix

5 Functions of Blood Transport of dissolved substancesRegulation of pH and ionsRestriction of fluid losses at injury sitesDefense against toxins and pathogensStabilization of body temperature

Whole BloodFigure 191aPlasma: Fluid-WaterDissolved plasma proteinsOther solutes Formed elements: all cells and solids

Plasma Is similar to, and exchanges fluids with, interstitial fluidIs matrix of formed elements

3 Types of Formed Elements Red blood cells (RBCs) or erythrocytes:transport oxygenWhite blood cells (WBCs) or leukocytes:part of the immune systemPlatelets:cell fragments involved in clotting HemopoiesisProcess of producing formed elementsBy myeloid and lymphoid stem cells

3 General Characteristics of Blood38C (100.4F) is normal temperatureHigh viscositySlightly alkaline pH (7.357.45) *Blood volume (liters) = 7% of body weight (kilograms):adult male: 5 to 6 litersadult female: 4 to 5 liters

PlasmaFigure 191bMakes up 5060% of blood volumeMore than 90% of plasma is water

Extracellular FluidsInterstitial fluid (IF) and plasmaMaterials plasma and IF exchange across capillary walls:waterionssmall solutes * Differences between Plasma and IFLevels of O2 and CO2Dissolved proteins:plasma proteins do not pass through capillary walls

3 Classes of Plasma ProteinsAlbumins (60%)-Transport substances:fatty acidsthyroid hormonessteroid hormonesGlobulins (35%)- Antibodies, also called immunoglobulins Transport globulins (small molecules):hormone-binding proteinsmetalloproteinsapolipoproteins (lipoproteins)steroid-binding proteins

Fibrinogen (4%)-Molecules form clots Produce long, insoluble strands of fibrin

Other Plasma Proteins1% of plasma:changing quantities of specialized plasma proteins enzymes, hormones, and prohormonesOrigins of Plasma Proteins :90% made in liverAntibodies made by plasma cellsPeptide hormones made by endocrine organsSerum -liquid part of a blood sample:in which dissolved fibrinogen has converted to solid fibrin

KEY CONCEPTTotal blood volume (liters) = 7% of body weight (kilograms) About 1/2 the volume of whole blood is cells and cell productsPlasma resembles interstitial fluid, but contains a unique mixture of proteins not found in other extracellular fluids

What are the characteristics and functions of red blood cells?

Red Blood CellsRed blood cells (RBCs) make up 99.9% of bloods formed elementsRed blood cell count: measurementsreports the number of RBCs in 1 microliter whole blood RBC: normal #male: 4.56.3 millionfemale: 4.5.5 million

Hematocrit (packed cell volume, PCV):percentage of RBCs in centrifuged whole bloodHematocrit: normal %male: 452female: 347

RBC StructureSmall and highly specialized discThin in middle and thicker at edgeFigure 192dLifespan of RBCsLack nuclei, mitochondria, and ribosomesLive about 120 days

Importance of RBC Shape and SizeHigh surface-to-volume ratio:quickly absorbs and releases oxygenDiscs form stacks:smoothes flow through narrow blood vesselsDiscs bend and flex entering small capillaries:7.8 m RBC passes through 4 m capillary

Hemoglobin (Hb) Protein molecule, transports respiratory gasesNormal hemoglobin (adult male):1418 g/dl whole blood

Hemoglobin StructureComplex quaternary structureFigure 193

Hemoglobin Structure4 globular protein subunits:each with 1 molecule of hemeeach heme contains 1 iron ionIron ions easily:associate with oxygen (oxyhemoglobin) or dissociate from oxygen (deoxyhemoglobin)

Fetal HemoglobinStrong form of hemoglobin found in embryosTakes oxygen from mothers hemoglobin CarbaminohemoglobinWith low oxygen (peripheral capillaries):hemoglobin releases oxygenbinds carbon dioxide and carries it to lungs

AnemiaHematocrit or hemoglobin levels are below normalIs caused by several conditions

Recycling RBCsFigure 194

Recycling RBCs1% of circulating RBCs wear out per day: about 3 million RBCs per secondMacrophages of liver, spleen, and bone marrow:monitor RBCsengulf RBCs before membranes rupture (hemolyze)

Diagnosing DisordersHemoglobinuria:hemoglobin breakdown products in urine due to excess hemolysis in blood streamHematuria:whole red blood cells in urine due to kidney or tissue damage

Hemoglobin RecyclingPhagocytes break hemoglobin into components: globular proteins to amino acidsheme to biliverdin Iron Iron RecyclingTo transport proteins (transferrin) To storage proteins (feritin and hemosiderin

Breakdown 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 stercobilins

RBC MaturationFigure 195Erythropoiesis - Red blood cell formation Occurs only in red bone marrow (myeloid tissue)Stem cells mature to become RBCs

HemocytoblastsStem cells in bone marrow divide to produce:myeloid stem cells: become RBCs, some WBCs lymphoid stem cells: become lymphocytes

Stages of RBC MaturationMyeloid stem cell ProerythroblastErythroblastsReticulocyteMature RBC Components for Building red blood cells amino acidsironvitamins B12, B6, and folic acid

Stimulating HormonesErythropoietin (EPO) Also called erythropoiesis-stimulating hormone:secreted when oxygen in peripheral tissues is low (hypoxia) due to disease or high altitude

RBC TestsTable 191

KEY CONCEPT- RBCRed blood cells (RBCs) are the most numerous cells in the body RBCs circulate for approximately 4 months before recyclingSeveral million are produced each secondHemoglobin in RBCs transports: oxygen from lungs to peripheral tissuescarbon dioxide from tissues to lungs

Blood Typing -Surface AntigensAre cell surface proteins that identify cells to immune system Normal cells are ignored and foreign cells attacked

4 Basic Blood TypesFigure 196aBlood types are genetically determinedBy presence or absence of RBC surface antigens A, B, Rh

4 Basic Blood TypesA (surface antigen A)B (surface antigen B)AB (antigens A and B)O (neither A nor B) AgglutinogensAntigens on surface of RBCsScreened by immune system Plasma antibodies attack (agglutinate) foreign antigens

Blood Plasma AntibodiesType A: type B antibodiesType B: type A antibodiesType O: both A and B antibodiesType AB: neither A nor B

The Rh FactorAlso called D antigenEither Rh positive (Rh+) or Rh negative (Rh) Only sensitized Rh blood has anti-Rh antibodies

Cross-ReactionAlso called transfusion reactionPlasma antibody meets its specific surface antigenBlood will agglutinate and hemolyzeIf donor and recipient blood types not compatible

Blood Type Test Determines blood type and compatibilityFigure 197Cross-Match TestPerformed on donor and recipient blood for compatibilityWithout cross-match, type O is universal donor

Based on structures and functions, what are the types of white blood cells, and what factors regulate the production of each type?

White Blood Cells (WBCs) Also called leukocytes Do not have hemoglobinHave nuclei and other organelles WBC Functions:Defend against pathogensRemove toxins and wastesAttack abnormal cells

WBC MovementMost WBCs in:connective tissue properlymphatic system organs Small numbers in blood:6000 to 9000 per microliter Circulating WBCsMigrate out of bloodstreamHave amoeboid movementAttracted to chemical stimuli (positive chemotaxis)Some are phagocytic:neutrophils, eosinophils, and monocytes

5 Types of WBCsFigure 199NeutrophilsEosinophilsBasophilsMonocytesLymphocytes

Neutrophils Also called polymorphonuclear leukocytes 5070% of circulating WBCsPale cytoplasm granules with:lysosomal enzymesbactericides (hydrogen peroxide and superoxide)

Neutrophil Action Very active, first to attack bacteriaEngulf pathogensDigest pathogensRelease prostaglandins and leukotrienesForm pus

DegranulationRemoving granules from cytoplasmDefensins:peptides from lysosomesattack pathogen membranes

Eosinophils Also called acidophils24% of circulating WBCsAttack large parasitesExcrete toxic compounds:nitric oxidecytotoxic enzymes

Eosinophil Actions Are sensitive to allergens Control inflammation with enzymes that counteract inflammatory effects of neutrophils and mast cells

Basophils Are less than 1% of circulating WBCsAre smallAccumulate in damaged tissue Basophil Actions Release histamine:dilates blood vesselsRelease heparin:prevents blood clotting

Monocytes 28% of circulating WBCsAre large and sphericalEnter peripheral tissues and become macrophages Macrophage Actions Engulf large particles and pathogensSecrete substances that attract immune system cells and fibroblasts to injured area

Lymphocytes2030% of circulating WBCsAre larger than RBCsMigrate in and out of bloodMostly in connective tissues and lymphatic organs Lymphocyte Actions Are part of the bodys specific defense system

3 Classes of LymphocytesT cells -Cell-mediated immunityAttack foreign cells directly2. B cells -Humoral immunityDifferentiate into plasma cells Synthesize antibodies3. Natural killer (NK) cells -Detect and destroy abnormal tissue cells (cancers)

The Differential Count of Circulating WBCsDetects changes in WBC populationsInfections, inflammation, and allergic reactions WBC DisordersLeukopenia:abnormally low WBC countLeukocytosis:abnormally high WBC countLeukemia:extremely high WBC count

KEY CONCEPTRBCs outnumber WBCs 1000:1 WBCs defend against infection, foreign cells, or toxinsWBCs clean up and repair damaged tissuesThe most numerous WBCs: neutrophils engulf bacteriaLymphocytes-are responsible for specific defenses of immune response

WBC ProductionOrigins and Differentiation of Formed ElementsPLAYFigure 1910

WBC ProductionAll blood cells originate from hemocytoblasts:which produce myeloid stem cells and lymphoid stem cellsMyeloid Stem CellsDifferentiate into progenitor cells:which produce all WBCs except lymphocytes

LymphocytesAre produced by lymphoid stem cellsLymphopoiesis: the production of lymphocytes

WBC DevelopmentWBCs, except monocytes:develop fully in bone marrowMonocytes:develop into macrophages in peripheral tissues Other LymphopoiesisSome lymphoid stem cells migrate to peripheral lymphoid tissues (thymus, spleen, lymph nodes) Also produce lymphocytes

4 Colony-Stimulating Factors (CSFs) Hormones that regulate blood cell populations:1.M-CSF:-stimulates monocyte production2.G-CSF:-stimulates granulocyte productionneutrophils, eosinophils, and basophils

Summary: Formed Elements of BloodTable 193

PlateletsCell fragments involved in human clotting systemNonmammalian vertebrates have thrombocytes (nucleated cells) Circulates for 912 daysAre removed by spleen2/3 are reserved for emergencies

Platelet Counts150,000 to 500,000 per microliter Thrombocytopenia:abnormally low platelet countThrombocytosis:abnormally high platelet count

3 Functions of PlateletsRelease important clotting chemicalsTemporarily patch damaged vessel wallsActively contract tissue after clot formationPlatelet production- called thrombocytopoiesis:occurs in bone marrow

MegakaryocytesGiant cellsManufacture platelets from cytoplasm

Hormonal ControlsThrombopoietin (TPO)Inteleukin-6 (IL-6)Multi-CSF

What mechanisms control blood loss after injury, and what is the reaction sequence in blood clotting?

HemostasisThe cessation of bleeding:vascular phaseplatelet phasecoagulation phase

The Vascular PhaseA cut triggers vascular spasm 30-minute contractionFigure 1911a

3 Steps of the Vascular PhaseEndothelial cells contract: expose basal lamina to bloodstreamEndothelial cells release:chemical factors:ADP, tissue factor, and prostacyclinlocal hormones: endothelinsstimulate smooth muscle contraction and cell divisionEndothelial cell membranes become sticky:seal off blood flow

The Platelet PhaseBegins within 15 seconds after injuryFigure 1911b

The Platelet Phase Platelet adhesion (attachment):to sticky endothelial surfacesto basal laminaeto exposed collagen fibers Platelet aggregation (stick together):forms platelet plug closes small breaks

Activated Platelets Release Clotting Compounds Adenosine diphosphate (ADP) Thromboxane A2 and serotonin Clotting factorsPlatelet-derived growth factor (PDGF) Calcium ions

Platelet Plug: Size RestrictionProstacyclin:released by endothelial cellsinhibits platelet aggregationInhibitory compounds:released by other white blood cellsCirculating enzymes:break down ADPNegative (inhibitory) feedback:from serotoninDevelopment of blood clot:isolates area

The Coagulation PhaseBegins 30 seconds or more after the injuryFigure 1912a

The Coagulation PhaseBlood clotting (coagulation):Involves a series of steps converts circulating fibrinogen into insoluble fibrin Blood ClotFibrin networkCovers platelet plugTraps blood cellsSeals off area

Clotting Factors Also called procoagulants Proteins or ions in plasmaRequired for normal clotting

Plasma Clotting FactorsTable 194

Cascade ReactionsDuring coagulation phase Chain reactions of enzymes and proenzymesForm 3 pathways

3 Coagulation PathwaysExtrinsic pathway:begins in the vessel walloutside blood streamIntrinsic pathway:begins with circulating proenzymeswithin bloodstream

3 Coagulation PathwaysCommon pathway:where intrinsic and extrinsic pathways converge

The Extrinsic Pathway Damaged cells release tissue factor (TF) TF + other compounds = enzyme complexActivates Factor X

The Intrinsic Pathway Activation of enzymes by collagen Platelets release factors (e.g., PF3) Series of reactions activate Factor X

The Common Pathway Enzymes activate Factor XForms enzyme prothrombinaseConverts prothrombin to thrombinThrombin converts fibrinogen to fibrin

Functions of Thrombin Stimulates formation of tissue factorstimulates release of PF-3:forms positive feedback loop (intrinsic and extrinsic):accelerates clotting Bleeding TimeNormally, a small puncture wound stops bleeding in 14 minutes

Clotting: Area RestrictionAnticoagulants (plasma proteins):antithrombin-IIIalpha-2-macroglobulinHeparin Protein C (activated by thrombomodulin)Prostacyclin

Other FactorsCalcium ions (Ca2+) and vitamin K are both essential to the clotting process

Clot RetractionAfter clot has formed:Platelets contract and pull torn area togetherTakes 3060 minutes

FibrinolysisSlow process of dissolving clot:thrombin and tissue plasminogen activator (t-PA): activate plasminogen Plasminogen produces plasmin:digests fibrin strands

KEY CONCEPT-PlateletsPlatelets are involved in coordination of hemostasis (blood clotting)Platelets, activated by abnormal changes in local environment, release clotting factors and other chemicalsHemostasis is a complex cascade that builds a fibrous patch that can be remodeled and removed as the damaged area is repaired

SUMMARY (1)Functions of cardiovascular system5 functions of bloodStructure of whole blood:plasma and formed elementsProcess of blood cell formation (hemopoiesis)3 classes of plasma proteins:albuminsglobulinsfibrinogen

SUMMARY (2)RBC structure and functionHemoglobin structure and function RBC production and recyclingBlood types:ABO and RhWBC structure and function5 types of WBCs:neutrophils eosinophils basophils monocytes lymphocytes

SUMMARY (3)Differential WBC counts and diseaseWBC productionPlatelet structure and functionPlatelet production3 phases of hemostasis:vascular platelet coagulationFibrinolysis