Download Blood physiology

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 (Thrombocytes)
• Main function:
– Maintain homeostasis
• Buffering pH
• Humoral regulation
• Body temperature regulation
– Transportation:
• Gases, nutrients, hormones, and so on.
– Host defense:
• Immune reaction, coagulation.
Section 1 Components and Characteristic
Water: 93-95%
Plasma: 50-60%
Whole
blood
Solutes: 5-7% Proteins:
Nutrients
Products
Electrolytes:
Others: urea, gases.
WBC, Platelet: 1%
RBC: 40-50% (male)
37-48% (female)
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;
buffer 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,
hormones, 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.(During fetal development, hematopoiesis
occurs in multiple waves throughout the developing embryo and fetus,
including extraembryonic yolk sac (YS), the para-aortic region of the
embryo, fetal liver, and placenta before eventually homing to the bone
marrow where it occurs just before birth)
• Third month: liver
• Fourth month: bone marrow
– Postnatal stages:
• Bone marrow of almost any bone, predominantly by
flat bones and long bones.
100
100
Hemopoitic
activity (%)
Yolk Sac
Bone morrow
Liver
Lymph nodes
Spleen
0
1
2
3
4
5
6
7
8
9
Prenatal age (months)
Proportion of Red
Morrow (%)
100
birth
100
Vertebrate
Tibia
Sternum
Femur
10
20
30
Ribs
40
50
Postnatal age (years)
60
70
80
90
– 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
hematopoietic cells in the marrow.
– Colony-stimulating factors (CSF): see a table in next slide.
– Cytokines:
• IL-1, stem cell factor (CSF), 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.
Hematopoietic growth factors
Growth Factors
Function: stimulate progenitor
of the followings:
GM-CSF (granulocytemacrophage 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
Red blood cells (erythrocytes)
• Circular, biconcave discs without nuclei. 7~8m,
thickness 1~2.5 m.
• Cell count and volume:
– Hematocrit: Percentage of blood volume occupied by
packed cell volume.
– Volume:
• 4.5~5.51012/L, average 5.01012/L (male).
• 3.8~4.61012/L, average 4.21012/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, 2~5g/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)

EPO
Pronormblast (precursor)

Normoblast, Reticulocyte

Mature RBC (without nucleus)
• Erythropoietin (EPO):
– A glycoprotein, 34kd. Produced in interstitial cells in cortical
kidney such as fibroblast, endothelial cells.
– Roles:
• Erythrocytic progenitor proliferate and differentiate to
precursor.
• 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:
– 4~10109/L, average is 7109/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:
– 10~12m, 2.0~7.0109/L, 60-70%.
– Function:
• Phagocytosis: older cells, becteria, dead tissues, and
other foreign substances.
• To execute non-specific immune activity in first front.
• Monocytes:
– 15~30m, 0.12 ~ 0.8109/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
neutrophils, 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:
– 0.8~4.0109/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, 5hydroxytryptamine 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
thrombin
vWF
ADP and TXA2
fibrin
plasmin
fibrinogen
Blood Coagulation
Fibrinolysis
• Anatomic physiology of platelet:
– 2~4 m, thickness 1m.
Fibrinogen
GP IIb/III a
Phospholipid
Va
Ca2+
Receptor
X
GPI
vWF
– Membrane:
• Receptor: For adhension, aggregation and
coagulation.
• 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: >1000109/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
platelets (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 
thromboxane 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
(primary 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/IIIa.
– 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
indomethacin, 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
Prekallikrein
Fletcher factor
Intrinsi
c
High molecular weight
kininogen (HMWK)
contact activation cofactor; Fitzgerald, Flaujeac Williams factor
Intrinsi
c
Characteristic
I
Fibrinogen
Both
II
Prothrombin
Both
III
Tissue Factor
Extrins
ic
Contains N-term. gla
segment
-
IV
Calcium
Both
V
Proaccelerin, labile factor, accelerator (Ac-) globulin
Both
VI (Va)
Accelerin
VII
Proconvertin, serum prothrombin conversion accelerator (SPCA),
cothromboplastin
Extrins
ic
Endopeptidase with gla
residues
VIII
Antihemophiliac factor A, antihemophilic globulin (AHG)
Intrinsi
c
Protein cofactor
IX
Christmas Factor,
antihemophilic factor B,plasma thromboplastin component (PTC)
Intrinsi
c
Endopeptidase with gla
residues
X
Stuart-Prower Factor
Both
Endopeptidase with gla
residues
XI
Plasma thromboplastin antecedent (PTA)
Intrinsi
c
Endopeptidase
XII
Hageman Factor
Intrinsi
c
Endopeptidase
XIII
Protransglutaminase,
fibrin stabilizing factor (FSF), fibrinoligase
Both
Transpeptidase
Protein cofactor
This is Va, redundant to
Factor V
clotting cascade
Stage 1: Formation
of prothrombin
activator.
Stage 2:
Conversion of
prothrombin
to thrombin.
Stage 3: conversion of
fibrinogen to fibrin
• 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
response 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)
Antithrombin
III
50
Antiserine
protease
240
2antiplasma
70
Antiplasmin
70
2macroglobulin
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.
Anticoagulation pathway
VIII
VIIIa
VIIIi
PS
X
X
aPC
PS
V
+
Va
FII
PC
Vi
Thrombin
FI
Fibrin
• 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
Activator
plasminogen
plasmin
Inhibitor
fibrin
fibrin degradation products
Activator: Tissue plasminogen activator (tPA), urokinase.
Plasmin, a serine protease, is inhibited by 2-antiplasma.
• tPA:
– Released from vascular endothelial cells following
injury;
– Binds to fibrin and is consequently activated.
• Urokinase:
– Produced as the precursor, prourokinase by
epithelial 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
aggregation.
– 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
the 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
coagulation (DIC) and/or enzymatic destruction of
coagulation factors.
Blood grouping and transfusion
• The discovery of blood groups:
– 1901, Austrian Karl Landsteiner
discovered 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.
ABO grouping
Blood group A：A antigens on the surface of RBC,
B antibodies in blood plasma.
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
Which blood group do you belong to?
A Rh+
B Rh+
AB Rh+
O Rh+
A Rh-
B Rh-
AB Rh-
O Rh-
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.
• 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.
People with blood group O are called
“universal donors”.
People with blood group AB are called
“universal receivers”.
• 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
Recipient
RBC (co-lateral)
Serum (main lateral)
Cross match test