chapter 19: blood biology 141 a&p brashear-kaulfers
TRANSCRIPT
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Chapter 19: BloodBiology 141 A&PBrashear-Kaulfers
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What are the components of the cardiovascular system, and their major functions?
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The Cardiovascular SystemA circulating transport system:a pump (the heart)a conducting system (blood vessels)a fluid medium (blood)
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Functions of the Cardiovascular SystemTo transport materials to and from cells:oxygen and carbon dioxidenutrientshormonesimmune system components waste products
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What are the important components and major functions of blood?
BloodIs specialized fluid of connective tissue -contains cells suspended in a fluid matrix
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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
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Whole BloodFigure 191aPlasma: Fluid-WaterDissolved plasma proteinsOther solutes Formed elements: all cells and solids
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Plasma Is similar to, and exchanges fluids with, interstitial fluidIs matrix of formed elements
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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
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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
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PlasmaFigure 191bMakes up 5060% of blood volumeMore than 90% of plasma is water
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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
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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
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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
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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
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What are the characteristics and functions of red blood cells?
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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
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RBC StructureSmall and highly specialized discThin in middle and thicker at edgeFigure 192dLifespan of RBCsLack nuclei, mitochondria, and ribosomesLive about 120 days
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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
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Hemoglobin (Hb) Protein molecule, transports respiratory gasesNormal hemoglobin (adult male):1418 g/dl whole blood
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Hemoglobin StructureComplex quaternary structureFigure 193
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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)
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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
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AnemiaHematocrit or hemoglobin levels are below normalIs caused by several conditions
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Recycling RBCsFigure 194
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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)
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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
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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
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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
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RBC MaturationFigure 195Erythropoiesis - Red blood cell formation Occurs only in red bone marrow (myeloid tissue)Stem cells mature to become RBCs
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HemocytoblastsStem cells in bone marrow divide to produce:myeloid stem cells: become RBCs, some WBCs lymphoid stem cells: become lymphocytes
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Stages of RBC MaturationMyeloid stem cell ProerythroblastErythroblastsReticulocyteMature RBC Components for Building red blood cells amino acidsironvitamins B12, B6, and folic acid
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Stimulating HormonesErythropoietin (EPO) Also called erythropoiesis-stimulating hormone:secreted when oxygen in peripheral tissues is low (hypoxia) due to disease or high altitude
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RBC TestsTable 191
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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
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Blood Typing -Surface AntigensAre cell surface proteins that identify cells to immune system Normal cells are ignored and foreign cells attacked
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4 Basic Blood TypesFigure 196aBlood types are genetically determinedBy presence or absence of RBC surface antigens A, B, Rh
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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
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Blood Plasma AntibodiesType A: type B antibodiesType B: type A antibodiesType O: both A and B antibodiesType AB: neither A nor B
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The Rh FactorAlso called D antigenEither Rh positive (Rh+) or Rh negative (Rh) Only sensitized Rh blood has anti-Rh antibodies
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Cross-ReactionAlso called transfusion reactionPlasma antibody meets its specific surface antigenBlood will agglutinate and hemolyzeIf donor and recipient blood types not compatible
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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
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Based on structures and functions, what are the types of white blood cells, and what factors regulate the production of each type?
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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
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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
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5 Types of WBCsFigure 199NeutrophilsEosinophilsBasophilsMonocytesLymphocytes
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Neutrophils Also called polymorphonuclear leukocytes 5070% of circulating WBCsPale cytoplasm granules with:lysosomal enzymesbactericides (hydrogen peroxide and superoxide)
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Neutrophil Action Very active, first to attack bacteriaEngulf pathogensDigest pathogensRelease prostaglandins and leukotrienesForm pus
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DegranulationRemoving granules from cytoplasmDefensins:peptides from lysosomesattack pathogen membranes
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Eosinophils Also called acidophils24% of circulating WBCsAttack large parasitesExcrete toxic compounds:nitric oxidecytotoxic enzymes
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Eosinophil Actions Are sensitive to allergens Control inflammation with enzymes that counteract inflammatory effects of neutrophils and mast cells
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Basophils Are less than 1% of circulating WBCsAre smallAccumulate in damaged tissue Basophil Actions Release histamine:dilates blood vesselsRelease heparin:prevents blood clotting
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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
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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
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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)
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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
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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
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WBC ProductionOrigins and Differentiation of Formed ElementsPLAYFigure 1910
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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
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LymphocytesAre produced by lymphoid stem cellsLymphopoiesis: the production of lymphocytes
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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
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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
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Summary: Formed Elements of BloodTable 193
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PlateletsCell fragments involved in human clotting systemNonmammalian vertebrates have thrombocytes (nucleated cells) Circulates for 912 daysAre removed by spleen2/3 are reserved for emergencies
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Platelet Counts150,000 to 500,000 per microliter Thrombocytopenia:abnormally low platelet countThrombocytosis:abnormally high platelet count
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3 Functions of PlateletsRelease important clotting chemicalsTemporarily patch damaged vessel wallsActively contract tissue after clot formationPlatelet production- called thrombocytopoiesis:occurs in bone marrow
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MegakaryocytesGiant cellsManufacture platelets from cytoplasm
Hormonal ControlsThrombopoietin (TPO)Inteleukin-6 (IL-6)Multi-CSF
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What mechanisms control blood loss after injury, and what is the reaction sequence in blood clotting?
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HemostasisThe cessation of bleeding:vascular phaseplatelet phasecoagulation phase
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The Vascular PhaseA cut triggers vascular spasm 30-minute contractionFigure 1911a
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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
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The Platelet PhaseBegins within 15 seconds after injuryFigure 1911b
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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
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Activated Platelets Release Clotting Compounds Adenosine diphosphate (ADP) Thromboxane A2 and serotonin Clotting factorsPlatelet-derived growth factor (PDGF) Calcium ions
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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
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The Coagulation PhaseBegins 30 seconds or more after the injuryFigure 1912a
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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
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Clotting Factors Also called procoagulants Proteins or ions in plasmaRequired for normal clotting
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Plasma Clotting FactorsTable 194
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Cascade ReactionsDuring coagulation phase Chain reactions of enzymes and proenzymesForm 3 pathways
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3 Coagulation PathwaysExtrinsic pathway:begins in the vessel walloutside blood streamIntrinsic pathway:begins with circulating proenzymeswithin bloodstream
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3 Coagulation PathwaysCommon pathway:where intrinsic and extrinsic pathways converge
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The Extrinsic Pathway Damaged cells release tissue factor (TF) TF + other compounds = enzyme complexActivates Factor X
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The Intrinsic Pathway Activation of enzymes by collagen Platelets release factors (e.g., PF3) Series of reactions activate Factor X
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The Common Pathway Enzymes activate Factor XForms enzyme prothrombinaseConverts prothrombin to thrombinThrombin converts fibrinogen to fibrin
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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
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Clotting: Area RestrictionAnticoagulants (plasma proteins):antithrombin-IIIalpha-2-macroglobulinHeparin Protein C (activated by thrombomodulin)Prostacyclin
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Other FactorsCalcium ions (Ca2+) and vitamin K are both essential to the clotting process
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Clot RetractionAfter clot has formed:Platelets contract and pull torn area togetherTakes 3060 minutes
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FibrinolysisSlow process of dissolving clot:thrombin and tissue plasminogen activator (t-PA): activate plasminogen Plasminogen produces plasmin:digests fibrin strands
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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
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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
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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
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SUMMARY (3)Differential WBC counts and diseaseWBC productionPlatelet structure and functionPlatelet production3 phases of hemostasis:vascular platelet coagulationFibrinolysis