Chapter 3 Blood Physiology

• Blood composition and properties• Blood cells

– Hematopoiesis

– RBC: function, anemia.

– WBC

– Platelet: function, coagulation and fibrinolysis.

• Blood grouping and transfusion

Introduction

• Blood volume: 7~8% (70-80ml/kg B.W)– Plasma (60%) and cells (40%).

• Types of blood cells:– RBC (Erythrocytes), WBC (Leukocytes) and Platelets (Thrombocyte

s)

• Main function:– Maintain homeostasis

• Buffering pH• Humoral regulation• Body temperature regulation

– Transportation: • Gases, nutrients, hormones, and so on.

– Host defense: • Immune reaction, coagulation.

Water: 93-95%

Plasma: 50-60%

Solutes: 5-7% Proteins:

Nutrients

Products

Electrolytes:

Others: urea, gases.

WBC, Platelet: 1%

RBC: 40-50% (male)

37-48% (female)

Section 1 Components and Characteristic

Whole

blood

Blood Components

• Water:– 93~95% (plasma); 65~68% (RBC); 81~86% (whole blood).

– Solvent, humoral balance, osmotic pressure.

• Electrolytes:– Na+, K+, Mg2+, Cl-, HCO3-, etc. Cell shape, pH.

• Proteins:– Albumin: 40-48g/L. Colloidal osmotic pressure; carrier; b

uffer pH.

– Globulin: 15-30g/L. Immune reaction: antibody; carrier.

– Fibrinogen: 2-4g/L. Blood coagulation.

– Hemoglobin (Hb):

• 120-160g/L (male), 110-150g/L (female)

• Function: carry gases.

• Others: – carbohydrates, lipids, amino acid, pigments, hormo

nes, gas (O2, CO2), and others like urea, uric acid.

Physical and chemical properties

• Blood pH:– Normal interval: 7.35~7.45.

• Regulated by lung and kidney.

• Viscosity:– Friction of molecules and cells in blood.– Relative viscosity:

• Whole blood: 4~5 times to water (RBC).

• Plasma: 1.6~2.4 times to water (Proteins).

• Anemia or body fluid loss.

• Osmotic pressure– Definition:

• An ability of a liquid to attract and retain water. It drives osmosis. 300mmol/L

– Composition and roles:• Crystal osmotic pressure: 298.7 mmol/L.

– Maintain shape and size of cells.

• Colloid osmotic pressure: 1.3 mmol/L.

– Retain blood volume

– Decide distribution of water between blood and interstitial fluid.

Section 2 Blood Cells

• Red blood cell

• White blood cell

• Platelet

Hemopoiesis

• The process of blood generation.

Cell Lineage Lifespan Daily Production Rate

RBC 120 days 2.5 109/L

Neutrophil 7 hours 0.85 109/L

Platelet 10 days 2. 5 109/L

• Ontogeny of Hematopoiesis– Prenatal stages:

• First month: yolk sac.

• Third month: liver

• Fourth month: bone marrow

– Postnatal stages:• Bone marrow of almost any bone, predominatantly b

y flat bones and long bones.

0 2 3 4 5 6 7 8 91

100 100

birth 20 30 40 50 60 70 80 9010

100 100

Yolk Sac Liver Bone morrow

SpleenLymph nodes

Prenatal age (months)

Postnatal age (years)

Tibia

Femur Ribs

Sternum

Vertebrate

Hem

opoi

tic

acti

vity

(%

)P

rop

orti

on o

f R

ed M

orro

w

(%)

– Stage 1, hemopoietic stem cells: pluripotent uncommitted stem cells.

– Stage 2, committed progenitor cell: unipotent committed stem cells. Includes:

• Erythrocytic progenitor cell

• Megakaryocytic progenitor cell

• Granulocytic progenitor cell

• Lymphocytic progenitor cell

– Stage 3, precursors (cell): immature cells, differentiate functional cells. Including:

• Ery. progenitor erythrocytes.

• Mega. progenitor platelets.

• Gran. progenitor granulocytes and monocytes.

• Lym. progenitor T and B lymphocytes.

• Hematopoietic growth factor and related molecules– Necessary for proliferation and differentation of hematop

oietic cells in the marrow.

– Colony-stimulating factors (CSF): see a table in next slide.

– Cytokines:

• IL-1, stem cell factor (SCF), etc.

– Extracellular matrix proteins:

• Sulfated glycosamimoglycans and heparin sulfate, may concentrate hematopoitic growth factors in local micro environment;

• Fibronectin and hemonectin, mediate adhension of cells, and may serve a growth promoting function.

Growth Factors Function: stimulate progenitor of the followings:

GM-CSF (granulocyte-macrophage CSF)

Granulocyte-monocyte

G-CSF (granulocyte CSF) Granulocyte

M-CSF (macrophage CSF) Monocyte

EPO (Erythropoietin) Erythrocyte

IL-1,3,6 (Interleukin-3, 1, 6) Myeloid lineage

TPO (Thrombopoietin) Platelet

Hematopoietic growth factors

Red blood cells (erythrocytes)

• Circular, biconcave discs without nuclei. 7~8m, thickness 1~2.5 m.

• Cell count and volume:– Hematocrit: Percentage of blood volume occupied by packe

d cell volume.

– Volume: • 4.5~5.51012/L, average 5.01012/L (male).

• 3.8~4.61012/L, average 4.21012/L (female).

• Physical properties– Permeability:

– Deformation:

– Fragility and hemolysis:

• Isosmotic solution and lower osmotic solution

– Suspension stability:

• The erythrocytes are very stable in suspension.

• Cause: repelling force of same charge and bigger surface area.

• Erythrocytes Sedimentation Rate (ESR): Sedimentated distance of RBC after one hour.

– 0~15 mm/h (male), 0~20 mm/h (female).

– Ratio of Surface area/Volume of RBC.

– Albumin, globulin, fibrinogen, and cholesterol.

– Rouleaux: RBC aggregate.

• Function of RBC:– The main constituent of RBC is hemoglobin.

– To deliver O2 to tissues by hemoglobin.

Hemoglobin (HB)

• HB is made up of two polypeptide chains and chains.

• Each polypeptide has alpha helical segments folded and bent into a globular configuration, with a heme ring within a pocket where the iron molecule can interact with oxygen.

• Hb formation materials:– Protein: enough intake from food.

– Iron: 3-4g/person. Mainly in Hb (70%).

• Degrading Hb: 95%.

• Absorbed from small intestine: 1mg/d, 5%.

• Microcytic hypochromic anemia: Lack of iron.

• RBC Maturation factors:– Vitamin B12:

• Cobalamine, 2~5g/d.

• Produced by gut bacteria (esp. in ruminants). Good sources include meat, liver, fish, eggs and milk.

• Absorbed in terminal ileum with intrinsic factor’ help.

• Function: Improve utilization of FA.

– Folic acid: • FA is essential for the synthesis DNA.

• Synthesized by microorganisms and higher plants.

• Good sources are green leafy vegetables, yeast and organ meats.

• Absorbed in the proximal jejunum.

– Lack of folic acid and vitb12: give rise to immature cells due to DNA synthesis derangement.

– Megaloblast anemia.

•Regulation of erythropoiesis: Hypoxia: EPO RBC

Hemopoitic stem cell (uncommitted progenitor)

Erythrocytic progenitor (committed progenitor)

Pronormblast (precursor)

Normoblast, Reticulocyte

Mature RBC (without nucleus)

EPO

• Erythropoietin (EPO): – A glycoprotein, 34kd. Produced in interstitial cells in cortical kidne

y such as fibroblast, endothelial cells.

– Roles:• Erythrocytic progenitor proliferate and differentiate to precurs

or.

• Accelerate precursor proliferation and differentiation.

• Promote bone marrow release reticulocytes.

• Renal type anemia: EPO production decrease

• Other hormones:– Androgen, thyroid hormone, parathyroid hormone,etc.

• RBC destruction:– Life span of RBC is about 120 days. Older cells

White blood cells (leucocyte)

• WBC: – 4~10109/L, average is 7109/L.– Include:

• neutrophil, eosinophil, basophil• monocyte, lymphocyte.

– Protection, execute specific and non-specific immune reaction.

• Physical and chemical properties – Chemotaxis: attracted by chemical substances released

by bacteria and foreign substances.– Movement: Move to chemotaxic source– Phagocytosis: engulf and digest

Composition and functions

• Neutrophil:– 10~12m, 2.0~7.0109/L, 60-70%.– Function:

• Phagocytosis: older cells, becteria, dead tissues, and other foreign substances.

• To execute non-specific immune activity in first front.

• Monocytes:– 15~30m, 0.12 ~ 0.8109/L, 3 ~ 8%.

– Monocytes-macrophages system:• Monocytes (in blood) wander into tissues and become macrophages

(50 ~ 80 m). Stronger phagocytosis.

• Contain many kinds of cytokines such as CSF, ILs, TNF, INF-a,b.

– Roles: • Engulf and clear: bacteria, vermins, older, necrotic tissues, dead neut

rophils, dead cells and fragments.

• Activate lymphocytes to execute specific immune response.

• Recognize and kill cancer cells.

• Produce CSF, Ils, TNF, INF-, , regulate growth of granulocytes.

• Lymphocytes:– 0.8~4.0109/L, 20 ~ 40%.– Development of lymphocyte:

• T lymphocyte: – lymphocytic stem cells T lymphocytes (thymus gland).

• B lymphocyte:– lymphocytic stem cells B lymphocytes (lymphoid tissue).

– Functions: • T lymphocytes: cellular type of immunity

• B lymphocytes: humoral immunity

• Eosinophils– 0.02~0.5 109/L, 0.5~5%.– Functions:

• Inhibit allergic reaction induced by basophils:

– Produce PGE to inhibit secretion of basophils;

– Engulf substances secreted by basophils;

– Secrete matters to hydrolyze histamine and 5-HT.

• Phagocytic action to some worms.

• Basophils– 0.0~1.0 109/L, 0~1%.– Large cytoplastmic granules contain heparin, 5-

hydroxytryptamine and histamine.– Function:

• Secrete heparin blood to prevent coagulation.

• Wander into tissue and become mast cell.

• Induce allergy.

Platelet

• Hemostasis:

– The process of blood clotting and then the subsequent dissolution of the clot.

Platelet activation adhension aggregation clot thrombus FDP

Blood Coagulation

thrombin ADP and TXA2 vWF fibrin

fibrinogen

plasmin

Fibrinolysis

• Anatomic physiology of platelet:– 2~4 m, thickness 1m.

Fibrinogen

Phospholipid

GP IIb/III a

Va

X

Ca2+

GPI

vWF

Receptor

– Membrane:• Receptor: For adhension, aggregation and coagulatio

n.

• Phospholipid: provides the lipid cofactors needed for coagulation reactions.

– Granules in platelet:-granules: coagulation factors, growth factors (e.g.

PDGF). -granules (dense bodies): Ca2+, ADP and serotonin.

– Volume: 100~300 109/L in adult.• Thrombocytopenia: <50 109/L, hemorrhage

• Thrombocytosis: >1000109/L, Thrombosis

• Physical properties– Adhesion:

• Mediated by von Willebrand factor (vWF).

• vWF is producted and stored in a-granules of platelets. Also synthesized by megakaryocytes.

• Function of vWF:– To act as a bridge between glycoprotein on the surface of pla

telets (GPIb/IX) and collagen fibrils.

– Serves as a carrier protein for factor VIII.

• von Willebrand Disease (vWD): deficiency in vWF a patient with long bleeding time, a low level of factor vWF/VIII complex.

• Bernard-Soulier Syndrome:deficiency of glycoprotein Ib/IX.

– Aggregation: • Activated platelets aggregate together.

• Activation of platelets: induced by thrombin.– Thrombin + receptor initiate signal cascade.

– G-protein, and phospholipase C(PLC-g).

– PLC-g IP3 and DAG formation.

– IP3 Ca2+ , and DAG PKC.

• Mechanisms:– Ca2+ phospholipase A2 (PLA2) arachidonic acid throm

boxane A2 (TXA2)

– PKC ADP fibrinogen to adhere to two platelet surface glycoproteins (GPIIb and GPIIIa) fibrinogen-induced platelet aggregation.

– Glanzmann-Thrombasthenia, deficiency of glycoprotein IIb/IIIa.

• Contractile function:

– PLC-g Ca2+ myosin light chain kinase (MLCK)

– MLCK phosphorylation of light chain of myosin

– Myosin interacts with actin

– Platelet morphology, motility, and clot retraction.

• Roles of platelet:– Platelet clot formation at the site of vessel injury (pr

imary hemostasis);

– Enhance activation of coagulation factors to solidify platelet clot by interlacing with fibrin (secondary hemostasis).

• Platelet function disorders: – Disorders of platelet adhesion:

• Bernard-Soulier Syndrome: deficiency of glycoprotein Ib/IX.

– Disorders of platelet aggregation: • Glanzmann-Thrombasthenia, deficiency of glycoprotein IIb/III

a.

– Disorders of platelet secretion: • Alpha or Dense Granules Deficiency.

– Disorders of platelet procoagulant activity:• Platelets fail to promote activation of the blood clotting proteins.

– Acquired platelet function disorders: • Drugs like aspirin, non-steroidal anti-inflammatory drugs like i

ndomethacin, ibuprofen.

Blood coagulation

• A process of blood from liquid to colloid. A serious of enzymes reactions.

• Coagulation factors:– Factors involved in the blood coagulation– Attentions:

• FIII come from tissue, others from plasma.

• FIV is Ca2+, and others are proteins.

• FII, VII, IX, XII exist as proenzymes.

Factor Trivial Name(s)Pathwa

y Characteristic

Prekallikrein Fletcher factorIntrinsi

c 

High molecular weight kininogen (HMWK)

contact activation cofactor; Fitzgerald, Flaujeac Williams factorIntrinsi

c 

I Fibrinogen Both-

II Prothrombin BothContains N-term. gla segme

nt

III Tissue FactorExtrins

ic-

IV Calcium Both-

V Proaccelerin, labile factor, accelerator (Ac-) globulin Both Protein cofactor

VI (Va) AccelerinThis is Va, redundant to Fac

tor V

VIIProconvertin, serum prothrombin conversion accelerator (SPCA), co

thromboplastinExtrins

icEndopeptidase with gla resi

dues

VIII Antihemophiliac factor A, antihemophilic globulin (AHG)Intrinsi

cProtein cofactor

IXChristmas Factor,

antihemophilic factor B,plasma thromboplastin component (PTC)Intrinsi

cEndopeptidase with gla resi

dues

X Stuart-Prower Factor BothEndopeptidase with gla resi

dues

XI Plasma thromboplastin antecedent (PTA)Intrinsi

cEndopeptidase

XII Hageman FactorIntrinsi

cEndopeptidase

XIIIProtransglutaminase,

fibrin stabilizing factor (FSF), fibrinoligaseBoth Transpeptidase

Stage 1: Formation of prothrombin activator.

Stage 2: Conversion of prothrombin to th

rombin.

Stage 3: conversion of fibrinogen to fibrin

clotting cascade

• Difference of stage 1:– Prothrombin-converting enzyme: Xa, Ca2+, V, PL.

– Difference of factor Xa:

• Intrinsic stage: – Start from XII. The intrinsic pathway requires factors VIII,

IX, X, XI, and XII. Also required are the proteins prekallikrein and high-molecular-weight kininogen, as well as Ca2+ and phospholipids secreted from platelets.

• Extrinsic stage: – Start from FIII (TF), is initiated at the site of injury in resp

onse to the release of TF.

– TF is a cofactor in the factor VIIa

– Factor VIIa, cleaves factor X to factor Xa

Prevention of coagulation

• Plasma inhibitors

• Fibrinolysis

• Role of the endothelial cells

Plasma inhibitors

Inhibitor Mol. Weight (kD)

Action Plasma Conc.

(mg/ml)Antithrombi

n III50 Antiserine pr

otease240

2-antiplasma

70 Antiplasmin 70

2-macroglobulin

725 Antiprotease 2500

Protein c 56 Anti-factor V and Viii

5

• Antithrombin III:– Nonspecific protease inhibitors

– Produced in liver and endothelial cells

– Inhibit active sites of FIXa,FXa,FXIa,FXIIa, thrombin.

• Protein C:

– Vitamin K-dependent protein

– Is activated to activited protein C (aPC) by thrombin in presence of endothelial cell-derived cofactor thrombomodulin.

– aPC inactivates FV and FVIII in presence of another vitamin K-dependent cofactor: protein S.

– See next slide.

X X

+ VaV

VIII VIIIa VIIIi

Vi

FII Thrombin

FI Fibrin

aPC

PS

PS

PC

Anticoagulation pathway

• Heparin: – A polysaccharide produced in basophilic mast cells

– Distributed in the pericapillary tissue.

– Abundant in lung, heart, liver, muscle tissues.

– Inhibit thrombin conversion.

– Promote antithrombin III activity.

• Calcium ions precipitants: – Sodium citrate

Fibrinolysis

• Fibrinolysis: – Process of liquefaction of fibrin

plasminogen plasmin

fibrin fibrin degradation products

Activator

Inhibitor

Activator: Tissue plasminogen activator (tPA), urokinase.Plasmin, a serine protease, is inhibited by 2-antiplasma.

• tPA:– Released from vascular endothelial cells following in

jury;

– Binds to fibrin and is consequently activated.

• Urokinase:– Produced as the precursor, prourokinase by epitheli

al cells lining excretory ducts.

– Role: to activate the dissolution of fibrin clots.

• plasminogen activator-inhibitors:– PAI-1 and PAI-2

Endothelial cells• Endothelium produces several inhibitors of hemostasis:

– Prostaglandin I2: • secreted by endothelial cells and is a potent inhibitor of platelet a

ggregation.

– Thrombomodulin: • Enhances the activiation of protein C by thrombin and results in

the inactivation of factor V and VIII.

– Heparans: • a heparin-like molecule, produced by endothelial cells. Increase t

he anticoagulant effect of antithrombin III.

– Plasminogen activator: • necessary for dissolution of fibrin clots, such as tPA.

Coagulation disorders

• Hemophilia A: – Deficiency of FVIII. The disease severity usually

parallels the factor VIII levels.

– Serve (< 1% VIII): with spontaneous bleeding;

– Moderate (1-5% VIII): with occasional bleeding, usually with trauma;

– Mild (6-30% VIII): with bleeding only after surgery or trauma.

– Therapy: administration of FVIII.

• Hemophilia B (Christmas Disease):– FIX deficiency.

– Treatment requires IX-rich material: fresh frozen plasma (FFP) or lyophilized concentrates proagulatant proteins.

• Decreased production of coagulation factors: – E.g. Liver disease, vitamin K malabsorption, dietary

deficiency of vitamin K.

• Inactivation of coagulation factors: – e.g. specific inhibitors, excessive activation of coagul

ation (DIC) and/or enzymatic destruction of coagulation factors.

Blood grouping and transfusion

• The discovery of blood groups: – 1901, Austrian Karl Landsteiner disc

overed human blood groups.

– Blood agglutination was an immunological reaction.

– Awarded the Nobel Prize in Physiology or Medicine in 1930.

• Agglutination:– Agglutinogen: antigen on membrane

of RBC.

– Agglutinin: antibody in the plasma.

• RBC grouping:– ABO, Rh, MnSs, lewis

– The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies.

Blood group A： A antigens on the surface of RBC, B antibodies in blood plasma.

ABO grouping

Blood group B ： B antigens on the surface of RBC, A antibodies in blood plasma.

Blood group AB： both A and B antigens on the surface of RBC, no A or B antibodies at all in blood plasma.

Blood group O： neither A or B antigens on the surface of RBC, but you have both A and B antibodies in blood plasma

• Antigens and antibodies:– Antigens:

• A, B.

• Carbohydrate

– Antibodies: Antibody A and B.• Ig M: congenital,

• Bigger Mr.

Rh grouping

• Original discovery:– Rhesus monkey: Red cells injected into rabbits got

serum injected back to Rhesus monkey, or human agglutination happens.

• Rh antigen and antibody– Antigen: D, E, C, c, e.

• 99% Chinese people are Rh+

• Minority in China 2-5% is Rh-

• 15% western people are Rh-

– Antibody: IgG

A Rh+ B Rh+ AB Rh+ O Rh+

A Rh- B Rh- AB Rh- O Rh-

Which blood group do you belong to?

Blood Transfusion

• Clinical significance:– ABO and Rh blood groups must be compatible between

the donor blood and the patient blood.

– Agglutinated RBC clog blood vessels or crack to becomes toxic when HB outside the cell.

• Cross-match test:– Main lateral: donor’s RBC and recipient’s serum.

– Co-lateral: donor’s serum and recipient’s RBC.

People with blood group O are called “universal donors”.

People with blood group AB are called “universal receivers”.

• Principle of blood transfusion:– Agglutination of main lateral: absolutely no.

– Both of main and co-lateral do not agglutinate:

– Co-lateral agglutinates but Main lateral: • slow and less amount of blood transfusion could be recommended.

• Clinical importance for Rh group:– Blood transfusion between Rh+ and Rh- persons.

– A mother who is Rh- woman give birth a baby who is Rh+.

– Preventive measure: given an injection of anti-Rh antibodies.

Donor

RBC

Serum (main lateral)

Recipient

Serum

RBC (co-lateral)

Cross match test