Physiology of Blood and Physiology of Blood and HemostasisHemostasis

Paul Dexter C. Santos MD FPCP FPSMOPaul Dexter C. Santos MD FPCP FPSMO

Tasks:Tasks:1. Describe the different components of blood and 1. Describe the different components of blood and

their functionstheir functions2. Explain the regulation (production and 2. Explain the regulation (production and

destruction) of red blood cells.destruction) of red blood cells.3. Describe the characteristics of rbc, hemoglobin 3. Describe the characteristics of rbc, hemoglobin

(Hb) and their relation to function. (Hb) and their relation to function. 4. Enumerate and explain some rbc abnormalities4. Enumerate and explain some rbc abnormalities5. Enumerate the different common blood tests and 5. Enumerate the different common blood tests and

indices used in the clinics. indices used in the clinics. 6. Explain the ABO and Rh blood group systems.6. Explain the ABO and Rh blood group systems.7. Explain what happens during transfusion reactions7. Explain what happens during transfusion reactions8. Discuss the events in blood coagulation. 8. Discuss the events in blood coagulation. 9. Discuss the different anti-clotting mechanisms. 9. Discuss the different anti-clotting mechanisms.

WHAT ARE THE WHAT ARE THE COMPONENTS OF COMPONENTS OF BLOOD?BLOOD?

WHAT ARE THE WHAT ARE THE FUNCTIONS OF BLOOD?FUNCTIONS OF BLOOD?

Maintain homeostasis:Maintain homeostasis: Body temperatureBody temperature Osmotic and ionic balanceOsmotic and ionic balance

Transport of:Transport of: OxygenOxygen NutrientsNutrients HormonesHormones

Defense:Defense: InfectionsInfections HemostasisHemostasis

Plasma ProteinsPlasma Proteins

Globulins:Globulins: globulins globulins

(liver): transport of fats (liver): transport of fats globulins (WBC): globulins (WBC):

immunoglobulinsimmunoglobulins

Albumin:Albumin: Major plasma Major plasma

proteinprotein Maintains oncotic Maintains oncotic

pressurepressure Carries other Carries other

molecules molecules (hormones and (hormones and drugs)drugs)

Produced in the Produced in the liverliver

Clotting factorsClotting factors FibrinogenFibrinogen

• Clinical Note:Clinical Note:• Synthetic Functions of LiverSynthetic Functions of Liver• Monoclonal gammopathyMonoclonal gammopathy

Oncotic pressure: the force that retains Oncotic pressure: the force that retains the fluids inside the blood vessels.the fluids inside the blood vessels.

Albumin maintains intravascular oncotic Albumin maintains intravascular oncotic pressurepressure

WHAT HAPPENS IF YOU WHAT HAPPENS IF YOU HAVE LOW ALBUMIN?HAVE LOW ALBUMIN?

Serum Protein Serum Protein ElectrophoresisElectrophoresis

Cellular elementsCellular elements

White blood cellsWhite blood cells Red blood cellsRed blood cells Platelets Platelets

Red Blood Cell Production: Red Blood Cell Production: Sites of ErythropoiesisSites of Erythropoiesis

FETUSFETUS Yolk SacYolk Sac LiverLiver Bone marrow, at birthBone marrow, at birth

CHILDREN & ADOLESCENTS CHILDREN & ADOLESCENTS Marrow of Long bones: humerus and femurMarrow of Long bones: humerus and femur

ADULTSADULTS Marrow of Axial Skeleton: ribs, sternum, Marrow of Axial Skeleton: ribs, sternum,

pelvispelvis Clinical Note: Liver re-assumes Clinical Note: Liver re-assumes hematopoietic functions in certain hematopoietic functions in certain disease states.disease states.

ErythropoiesErythropoiesisis

WHAT HAPPENS IF YOU WHAT HAPPENS IF YOU HAVE CHRONIC LUNG HAVE CHRONIC LUNG

DISEASE? OR YOU LIVE ON DISEASE? OR YOU LIVE ON TOP OF A MOUNTAIN?TOP OF A MOUNTAIN?

Chronic Lung Chronic Lung DiseasesDiseases

Increased Increased HematocritHematocrit

Increased Increased HemoglobinHemoglobin

Increased Increased ErythropoietinErythropoietin

Erythropoietin and dopingErythropoietin and doping

Increase in Increase in oxygen carrying oxygen carrying capacity of capacity of bloodblood

Increased Increased athletic athletic performanceperformance

Side effects:Side effects: HypertensionHypertension Venous Venous

thrombosisthrombosis

Erythropoietin and Chronic Kidney Erythropoietin and Chronic Kidney FailureFailure Kidneys unable to produce Kidneys unable to produce

erythropoietinerythropoietin Can give exogenous erythropoietin or Can give exogenous erythropoietin or

blood transfusionsblood transfusions

The Red Blood CellThe Red Blood Cell Biconcave Disc: Biconcave Disc:

Deformable and pliableDeformable and pliable Increased surface to volume ratioIncreased surface to volume ratio Short diffusion distance from Hgb to Short diffusion distance from Hgb to

oxygenoxygen

Anucleation and lack of organelles Anucleation and lack of organelles Further increases oxygen carrying Further increases oxygen carrying

capacitycapacity Life span of 120 daysLife span of 120 days

The Red Blood CellThe Red Blood Cell

Anaerobic MetabolismAnaerobic Metabolism Produces needed ATPProduces needed ATP Maintenance of membrane integrity / Maintenance of membrane integrity /

pliabilitypliability Maintains Iron in Ferrous stateMaintains Iron in Ferrous state Prevents Oxidation of proteinsPrevents Oxidation of proteins

The Red Blood CellThe Red Blood Cell

Importance of Membrane Importance of Membrane Pliability:Pliability: RBC can squeeze through small RBC can squeeze through small

blood capillariesblood capillaries Resist deformity and membrane Resist deformity and membrane

damagedamage

Hereditary Hereditary spherocytosis:spherocytosis: Errors in spectrin and Errors in spectrin and

ankyrin protein that ankyrin protein that maintains RBC shapemaintains RBC shape

Increased destruction of Increased destruction of RBCs (hemolytic anemiaRBCs (hemolytic anemia

RBC’s in relation to tonicity…RBC’s in relation to tonicity… Isotonic fluid: RBC maintains shapeIsotonic fluid: RBC maintains shape Hypotonic fluid: RBC swells, Hypotonic fluid: RBC swells,

hemoglobin escapes from the cell hemoglobin escapes from the cell membranemembrane

Hypertonic fluid: RBC becomes Hypertonic fluid: RBC becomes crenatedcrenated

HemoglobinHemoglobin

Globin: 4 Globin: 4 polypeptide chainspolypeptide chains Adult: 2 alpha and Adult: 2 alpha and

2 beta chains2 beta chains Fetus: 2 alpha and Fetus: 2 alpha and

2 gamma chains2 gamma chains 4 heme units 4 heme units

containing ironcontaining iron

Factors causing changes in oxygen Factors causing changes in oxygen affinity to hemoglobin:affinity to hemoglobin:

Fetal Hemoglobin Fetal Hemoglobin has higher affinity has higher affinity to oxygen (gamma to oxygen (gamma chain)chain)

Methemoglobin: Methemoglobin: oxidized Iron – oxidized Iron – unable to bind O2unable to bind O2

Sickle cell Sickle cell hemoglobinhemoglobin

IronIron Binds with apotransferrin (secreted with Binds with apotransferrin (secreted with

bile) in the intestinal lumenbile) in the intestinal lumen Fe + apotransferrin = transferrinFe + apotransferrin = transferrin Transferrin travels by pinocytosis from Transferrin travels by pinocytosis from

lumen to blood streamlumen to blood stream High iron stores = low Fe absorption High iron stores = low Fe absorption

(vice versa)(vice versa) Inside cells: apoferritin + Fe = Ferritin Inside cells: apoferritin + Fe = Ferritin

(stored Fe)(stored Fe)

HemochromatosisHemochromatosis Seen in patients with multiple blood Seen in patients with multiple blood

transfusions (thalassemias)transfusions (thalassemias) State of “Iron Overload”State of “Iron Overload” Liver, pancreas and heart failureLiver, pancreas and heart failure Treated with Iron chelationTreated with Iron chelation

Hypochromic anemiaHypochromic anemia Deficiency in ironDeficiency in iron RBC’s contain less hemoglobinRBC’s contain less hemoglobin Treated with Iron supplementationTreated with Iron supplementation

Fate of RBC’sFate of RBC’s

Natural ageing:Natural ageing: Loss of flexibility/pliabilityLoss of flexibility/pliability Sequestered by the spleenSequestered by the spleen

Engulfed by macrophagesEngulfed by macrophages Hemoglobin metabolizedHemoglobin metabolized

Bilirubin and biliverdinBilirubin and biliverdin Fe recycled Fe recycled

What is Anemia?What is Anemia?

AnemiaAnemia

Decrease in oxygen carrying capacity of Decrease in oxygen carrying capacity of bloodblood Decrease in number of RBC’sDecrease in number of RBC’s

Hemolytic anemia (increased destruction of Hemolytic anemia (increased destruction of RBC)RBC)

HemorrhageHemorrhage Aplastic anemia (primary bone marrow failure)Aplastic anemia (primary bone marrow failure)

Abnormal RBC functionAbnormal RBC function Iron deficiency anemiaIron deficiency anemia Vitamin B12, Folate deficiency (maturation Vitamin B12, Folate deficiency (maturation

problems)problems)

PolycythemiaPolycythemia

Primary polycythemia: polycythemia Primary polycythemia: polycythemia veravera

Secondary polycythemia:Secondary polycythemia: Congenital cyanotic heart diseasesCongenital cyanotic heart diseases Chronic lung diseasesChronic lung diseases

MaleMale FemaleFemale

Hematocrit, Hct Hematocrit, Hct (%)(%) 4747 4242

RBC Count RBC Count (10(1066/uL)/uL) 5.45.4 4.84.8

Hemoglobin, Hb Hemoglobin, Hb (g/dL)(g/dL) 1616 1414

Mean Corpuscular Volume, Mean Corpuscular Volume, MCV: (Hct/RBC) x 10 MCV: (Hct/RBC) x 10

8787 8787

Mean Corpuscular Hb, MCH: Mean Corpuscular Hb, MCH: (Hb/RBC) x 10(Hb/RBC) x 10

2929 2929

Mean Corpuscular Hb Conc, Mean Corpuscular Hb Conc, MCHC:(Hb/Hct)x100MCHC:(Hb/Hct)x100

3434 3434

Blood IndicesBlood Indices

Blood TypingBlood Typing

Presence of Antigens on the surface Presence of Antigens on the surface of RBC of RBC A Antigen A Antigen B Antigen B Antigen Rh Antigens (C,D,E)Rh Antigens (C,D,E)

ABO blood Grouping ABO blood Grouping

(H antigen with terminal (H antigen with terminal oligosaccharides)oligosaccharides) A - N-acetylgalactosamine A - N-acetylgalactosamine B - GalactoseB - Galactose O – has noneO – has none AB – has bothAB – has both

Blood Blood Type/PhenotyeType/Phenotye AntigenAntigen

AA AA

BB BB

ABAB A & BA & B

OO neitherneither

GenotypeGenotype

AA, AOAA, AO

BB, BOBB, BO

ABAB

OOOO

ABO inheritance/expression: 1 allele ABO inheritance/expression: 1 allele from each parentfrom each parent

ABO blood groupingABO blood grouping Presence of antibodies/agglutinins in the Presence of antibodies/agglutinins in the

serumserum IgM antibodiesIgM antibodies

Agglutinates red blood cells during transfusion Agglutinates red blood cells during transfusion mismatchmismatch

Type A blood: has Anti-B AgglutininsType A blood: has Anti-B Agglutinins Type B blood: has Anti-A AgglutininsType B blood: has Anti-A Agglutinins Type AB blood: has neither AgglutininsType AB blood: has neither Agglutinins Type O blood: has both Agglutinins Type O blood: has both Agglutinins

Can you give: Can you give: Type B blood to a type O person?Type B blood to a type O person? Type O blood to a type AB person?Type O blood to a type AB person? Type O blood to a type B person?Type O blood to a type B person? Type AB blood to a type A person?Type AB blood to a type A person?

AgglutinationAgglutination

Transfusion reactionsTransfusion reactions Agglutination of donor RBC’sAgglutination of donor RBC’s Hemolysis of RBCs (by macrophages and spleen)Hemolysis of RBCs (by macrophages and spleen)

Blood TypeBlood Type PreferredPreferred PermissiblePermissible

AA AA A,OA,O

BB BB B,OB,O

ABAB ABAB AB,A,B,OAB,A,B,O

OO OO OO

Rh blood groupRh blood group Rh+ = presence of D antigenRh+ = presence of D antigen

85% of caucasians85% of caucasians 99% of asians99% of asians

Rh - = absence of D antigenRh - = absence of D antigen No anti-D antibody/agglutinin initiallyNo anti-D antibody/agglutinin initially

Hemolytic disease of the newbornHemolytic disease of the newborn

Anti-D antibodies Anti-D antibodies (IgG type) attacks (IgG type) attacks fetal Rh+ red cellsfetal Rh+ red cells

Massive hemolysisMassive hemolysis Enlargement of Enlargement of

liver and spleenliver and spleen Prevented by giving Prevented by giving

Rh gammaglobulins Rh gammaglobulins (on 28(on 28thth week and week and after delivery)after delivery)

HemostasisHemostasis

HemostasisHemostasis Control of bleeding by the process of Control of bleeding by the process of

forming clots in the walls of damaged forming clots in the walls of damaged vessels while maintaining blood in the vessels while maintaining blood in the fluid statefluid state

EventsEvents VasoconstrictionVasoconstriction Formation of platelet plugFormation of platelet plug Blood coagulationBlood coagulation Clot retractionClot retraction

VasoconstrictionVasoconstriction Nervous reflexNervous reflex Myogenic responseMyogenic response Humoral factors (serotonin, Humoral factors (serotonin,

thromboxane A2)thromboxane A2)

Formation of platelet plugFormation of platelet plug Platelet activationPlatelet activation

What are Platelets?What are Platelets?

PlateletsPlatelets Fragments from Fragments from

megakaryocytesmegakaryocytes Contains contractile Contains contractile

proteins (actin/myosin)proteins (actin/myosin) Granules (ATP/ADP, Granules (ATP/ADP,

serotonin, Ca++, serotonin, Ca++, thromboxane A2)thromboxane A2)

No nucleusNo nucleus Life span 8-10 days (2-4 Life span 8-10 days (2-4

days for transfused days for transfused platelets)platelets)

Formation of platelet plugFormation of platelet plug Triggered by endothelial damageTriggered by endothelial damage Mediated by:Mediated by:

Von Willebrand Factor (VWF) Von Willebrand Factor (VWF) (subendothelium)(subendothelium)

ADPADP Thromboxane A2Thromboxane A2 Platelet activating factor (PAF)Platelet activating factor (PAF)

What’s the purpose of What’s the purpose of coagulation?coagulation?

Coagulation: formation of fibrinCoagulation: formation of fibrin

““INTRINSIC” PATHWAYINTRINSIC” PATHWAY TRIGGERED BYTRIGGERED BY

ACTIVATION OF FACTORS IN BLOOD BY ACTIVATION OF FACTORS IN BLOOD BY EXPOSURE TO COLLAGEN IN SUBENDOTHELIUMEXPOSURE TO COLLAGEN IN SUBENDOTHELIUM

““EXTRINSIC” PATHWAYEXTRINSIC” PATHWAY TRIGGERED TRIGGERED

EXPOSURE OF PLASMA TO TISSUE FACTOR (TF) EXPOSURE OF PLASMA TO TISSUE FACTOR (TF) WHEN THERE IS DAMAGE TO TISSUEWHEN THERE IS DAMAGE TO TISSUE

TF, A LIPOPROTEIN EXPRESSED ON SURFACE OF TF, A LIPOPROTEIN EXPRESSED ON SURFACE OF CELLS NOT NORMALLY IN CONTACT WITH CELLS NOT NORMALLY IN CONTACT WITH PLASMA PLASMA

Factors involved in the coagulation Factors involved in the coagulation cascadecascade

FACTORFACTOR NAMENAME FUNCTIONFUNCTION

II FibrinogenFibrinogen Linkage strandsLinkage strands

IIII ProthrombinProthrombin Activates I, V, VII, Activates I, V, VII, XIII, Prot C and PltsXIII, Prot C and Plts

VV ProaccelerinProaccelerin Helps Xa activate IIHelps Xa activate II

VIIVII Stable FactorStable Factor Activates IX and XActivates IX and X

VIIIVIII Anthihemophilia Anthihemophilia Helps IXa activate XHelps IXa activate X

IXIX Christmas Factor Christmas Factor Activates XActivates X

XX Stuart-Prower FStuart-Prower F Activates IIActivates II

XIXI Thromboplastin Thromboplastin antecedentantecedent

Activates IXActivates IX

XIIXII Hageman FactorHageman Factor Activates Kinin Activates Kinin systemsystem

XIIIXIII Fibrin stabilizerFibrin stabilizer Cross links fibrinCross links fibrin Factor IV: Calcium

FACTORFACTOR FUNCTIONFUNCTION

von WILLEBRAND Factorvon WILLEBRAND Factor Binds platelets and VIIIBinds platelets and VIII

Extrinsic Pathway InhibitorExtrinsic Pathway Inhibitor Inactivates VIIa and XaInactivates VIIa and Xa

Antithrombin IIIAntithrombin III Inactivates thrombin, Inactivates thrombin,

IXa, Xa, XIaIXa, Xa, XIa Protein CProtein C Inactivates Va, VIIa, PAIInactivates Va, VIIa, PAI

Plasminogen Plasminogen Lyses fibrinLyses fibrin

Alpha-2 antiplasminAlpha-2 antiplasmin Inhibits plasminInhibits plasmin

Tissue Plasminogen ActivatorTissue Plasminogen Activator Activates plasminogenActivates plasminogen

Plasminogen Activator Plasminogen Activator Inhibitor, PAIInhibitor, PAI

Inactivates tPA and Inactivates tPA and urokinaseurokinase

Clot retraction:Clot retraction: ““Shrinking” of the clotShrinking” of the clot Actin and Myosin of plateletsActin and Myosin of platelets Edges of blood vessels come closerEdges of blood vessels come closer

Anti-clotting Anti-clotting mechanismsmechanisms

1.1. Prostacyclin,PGIProstacyclin,PGI22 in endothelium in endothelium v. Thromboxane Av. Thromboxane A22 in platelets in platelets

2.2. Antithrombin III AND heparinAntithrombin III AND heparin

3.3. ThrombomodulinThrombomodulin

4.4. PlasminPlasmin

ThrombomodulinThrombomodulin Binds thrombinBinds thrombin Activates Protein C, with cofactor Activates Protein C, with cofactor

Protein SProtein S INACTIVATES Va & VIIIaINACTIVATES Va & VIIIa INACTIVATES INHIBITOR OF t-PAINACTIVATES INHIBITOR OF t-PA

Antithrombin IIIAntithrombin III Protease InhibitorProtease Inhibitor Inactivates clotting factorsInactivates clotting factors Facilitated by heparinFacilitated by heparin

PlasminPlasmin Activated from plasminogen by thrombin+tPAActivated from plasminogen by thrombin+tPA Plasmin lyses fibrinPlasmin lyses fibrin

Balance of Pro- and Anti- Balance of Pro- and Anti- coagulantscoagulants

Pro-Pro- Clotting factorsClotting factors ThrombinThrombin FibrinFibrin Plasminogen-Plasminogen-

activator-Inhibitorsactivator-Inhibitors

Anti-Anti- PlasminPlasmin AntithrombinAntithrombin tPAtPA Protein C and Protein C and

Protein SProtein S

Bleeding disorders:Bleeding disorders:

Tests:Tests: Bleeding time: assess qualitative platelet Bleeding time: assess qualitative platelet

functionfunction Platelet count: quantify plateletsPlatelet count: quantify platelets Clotting time: assess the coagulation cascadeClotting time: assess the coagulation cascade Prothrombin Time (PT): assess extrinsic and Prothrombin Time (PT): assess extrinsic and

common pathways (II, V, VII, X)common pathways (II, V, VII, X) Partial Thromboplastin Time (PTT): Assess Partial Thromboplastin Time (PTT): Assess

intrinsic and common pathways (VIII, IX, XI, intrinsic and common pathways (VIII, IX, XI, XII)XII)

Liver DiseasesLiver Diseases Liver produces most of clotting factors Liver produces most of clotting factors

(except VIII)(except VIII) Deranged PT and PTTDeranged PT and PTT

Vitamin K deficiencyVitamin K deficiency Vit K dependent: II, VII, IX, XVit K dependent: II, VII, IX, X Deranged PTDeranged PT

Protein C and S deficiencyProtein C and S deficiency Thrombotic complications (deep venous Thrombotic complications (deep venous

thrombosis, chronic pulmonary thrombosis, chronic pulmonary embolism)embolism)

HemophiliaHemophilia Hemophilia A: factor VIII deficiencyHemophilia A: factor VIII deficiency Hemophilia B: factor IX deficiencyHemophilia B: factor IX deficiency

Disseminated Intravascular Disseminated Intravascular Coagulation (DIC)Coagulation (DIC) Consumption of clotting factors - Consumption of clotting factors -

bleedingbleeding

AnticoagulantsAnticoagulants Heparin Heparin

Facilitates anti-thrombin IIIFacilitates anti-thrombin III EDTA (Ethyline Diamine Tetraacetic EDTA (Ethyline Diamine Tetraacetic

AcidAcid Chelates CalciumChelates Calcium

Warfarin and DicoumarolWarfarin and Dicoumarol Vitamin K dependent factors (FACTORS Vitamin K dependent factors (FACTORS

II, VII, IX, X, PROTEIN C & PROTEIN S) II, VII, IX, X, PROTEIN C & PROTEIN S) AspirinAspirin

Inhibits thromboxane A2 in plateletsInhibits thromboxane A2 in platelets

Thrombolytic therapyThrombolytic therapy

Streptokinase/Urokinase/ tPAStreptokinase/Urokinase/ tPA For acute myocardial infarction and For acute myocardial infarction and

ischemic strokesischemic strokes Dissolves the clot and restores organ Dissolves the clot and restores organ

perfusionperfusion Risk of bleedingRisk of bleeding