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