PHYSIOLOGY OF BLOOD
FUNCTIONS OF BLOOD
HOMEOSTATIC FUNCTION
buffering
thermoregulation (transport of heat)
TRANSPORT OF SUBSTANCES
(blood gases, nutrients, metabolites, vitamins, electrolytes…)
HUMORAL CONTROL OF ORGANISM (hormones)
DEFENCE OF ORGANISM (immune functions)
BLOOD CLOTTING
BASIC CHARACTERISTICS
•Suspension character
•6 - 8% total body mass
•55% - fluid phase (plasma)
•45% - formed phase (blood cells and platelets)
•Serum: from plasma during blood clotting – after consumption of
fibrinogen
BONE MARROW
Size (1600-3000 grams), activity.
Red bone marrow, yellow bone marrow.
Pluripotent stem cells.
Unipotent (determined) stem cells – differentiated cells.
Extra-medullar haematopoiesis – liver, lien – CHILDREN.
Medullar haematopoiesis – ADULTS.
Bone marrow examination – punction.
Bone marrow diseases.
Bone marrow transplantation.
Section of yellow bone marrow.
This bone marrow is yellow in its
fresh state because of the
abundance of yellowish adipocytes
present. The hemopoietic (*)
tissue is comparatively less
abundant than in red bone
marrow. The adipocytes, or fat
cells, (Ad) appear as large circular
clear spaces in this field. A
megakaryocyte (M) and venous
sinuses (S) are also labelled.
Source:
http://audilab.bmed.mcgill.ca/HA/ht
ml/blood_7_E.html
This bone marrow is referred to
as red marrow because it
contains few adipocytes, or fat
cells, among an abundance of
hemopoietic cells. It is difficult to
identify the individual precursors
of red and white blood cells
because they are closely packed
and condensed during the fixation
of the tissue (*).
The following elements are
identified: a megakaryocyte (M),
which is a very large polyploid
cell responsible for the production
of blood platelets one adipocyte
(Ad) two blood sinuses (S).
The walls of these vessels are
the sites where newly formed
erythrocytes and leukocytes pass
from the connective tissue into
the blood circulation.
Silverthorn, D. U. Human Physiology – an Integrated
Approach. 6th. edition. Pearson Education, Inc. 2012.
Source: Wikimedia Commons
Cells Cells /ml
(average)
Normal range Percent of total number of
leukocytes
Leukocytes
(total)
9000 3600 - 9600
Granulocytes
Neutrophiles
5400 3000 - 6000 42 – 75
Eozinophiles 275 150 - 300 1 - 4
Basophiles 35 0 - 100 0,4
Agranulocytes
Lymphocytes
2750 1200 - 3400 20 - 50
Monocytes 540 110 - 590 1,7 – 9,3
Erythrocytes
woman
4,2 – 5,4 . 106
men 4,5 - 6,3 . 106
Platelets 300 000 140000 – 440000
BLOOD CELLS
White blood cell count
RED BLOOD CELLS (ERYTHROCYTES)
Men Women
Hematocrit (Hct)
(%)
47 42
Erythrocytes (RBC)
(106/ml)
4,5 - 6,3 x106 4,2–5,4x106
Haemoglobin (Hb)
(g/l)
140 - 180 120 - 160
Mean volume of ery
(MCV) (fl)
= Hct x 10 / RBC (106/ml) 82 - 97 82 - 97
Mean content of Hb
in ery (MCH) (pg)
= Hb x 10 / RBC (106/ml) 27 - 33 27 - 33
Mean concentration
of Hb
in ery (g/100ml)
= Hb x 100 / Hct 32 - 36 32 - 36
Mean diameter of
ery
(MCD) (mm)
7,5 7,5
Function of erythrocytes: blood gases transport
RED BLOOD CELL EXAMINATION
1. Red blood cell count
• normocytemia
• erytrocytopenia (oligocytemia)
• polyglobulia (polycytemia)
2. Concentration of haemoglobin
• anaemia
3. Hematocrit
SHAPE AND SIZE OF ERYTHROCYTES
Shape: biconcave disc
OPTIMAL RATIO OF SURFACE TO VOLUME!!!
By 30% larger surface in comparison with the cell of the same size
but of round shape!!!
Anizocytosis – physiological, pathological. Price-Jones curve.
Size: 7,5 mm in diameter, 2 mm thickness – normocytes.
Microcytes (-osis): diameter below 6 mm, volume below 80 fl
Macrocytes (-osis), megalocytes: diameter above 8.2 mm, volume
above 95 fl
Amount of haemoglobin in one red blood cell: hypochromia
(below 27 pg Hb/ery), normochromia,
hyperchromia
Deformation of red blood cells. Fahraeus-Lindqvist effect.
megaloblastic anemia
vitamin B12 deficiency
folate deficiency
DNA synthesis disorders
iron deficiency
blood loss
increased demands on iron
insufficient iron intake
insufficient iron resorption
PočetEry(n)
Size of Ery (mm)
SHAPE AND SIZE OF RED BLOOD CELLS
- Price-Jones curve
BLOOD VISCOSITY
Plasma and serum behave almost like Newtonian fluids, whole blood like nonNewtonian
fluids.
BLOOD VISCOSITY
Whole blood has an anomalous viscosity.
Inner diameter
viscosity
FACTORS AFFECTING BLOOD VISCOSITY
Fibrinogen
- Interactions with Ery (nonNewtonian
fluid)
- Along with LDL
- Hyperfibrinogenemia - Ery
clustering
- Note - age, smoking
Hematocrit
- Influence on direct and
indirect interactions between
Ery and between Ery and
fibrinogen
- Increased hematocrit - tighter
interactions between Ery =
increased viscosity
FACTORS AFFECTING BLOOD VISCOSITY
Vessel diameter
- Fahraeus-Lindqvist effect
- Axial accumulation of Era local
changes in viscosity
- Plasma behavior in relation to
the vessel wall
Blood flow velocity
- Behavior of blood as a nonNewtonian
fluid
- The "threshold force" required
to set whole blood in motion
- Laminar flow and transport of
the Ery through the center of
the vessel
Temperature
- Under physiological conditions
a negligible parameter
- Note cryoglobulins (HBC)
ERYTHROCYTE MEMBRANE
Provides
- Deformability of Ery
- Necessary stability (in
circulation)
Stress of Ery
- Arterial system
- Microcirculation (change of shape,
deformation, capillaries below 7.5
mm)
- Changes in tonicity, pH and pO2MP cca -9.0 mV
ERYTHROCYTE MEMBRANE
Membrane lipids
Phospholipid bilayer +
glycolipids + cholesterol
- Asymmetric distribution
- External -
phosphatidylcholine,
sphingomyelin
- Internal -
phosphatidylethanolamine,
phosphatidylserine
Outward-facing sugar
components - antigenic
structures
Clinical overlap
- Loss of Ery membrane asymmetry
- Activation of prothrombin to thrombin
conversion
- Signal for macrophages - elimination of Ery
- Thalassemia, diabetes mellitus
ERYTHROCYTE MEMBRANE
Membrane proteins
- About 12 major and 100 minor proteins; integral and peripheral
Transport proteins
- Band 3 (Diego Blood group)
- mediating the exchange of chloride (Cl−) for bicarbonate (HCO3
−) across a plasma membrane
- Aquaporin 1 = water channel (Colton Blood Group)
- GLUT1
- Jk antigen
- on a protein responsible for urea transport in the red blood cells and the kidney (aka human urea
transporter 11- HUT11 or UT-B1)
- Rh-associated glycoprotein (RHAG) (Rh Blood Group)
- an ammonia transporter protein
- Na+/K+-ATPase
- Ca2+-ATPase
- Na-K-Cl cotransporter
- Sodium-chloride symporter
- Chloride potassium symporter
- Potassium intermediate/small conductance calcium-activated channel (Gardos channel)
Cell adhesion proteins
- ICAM-4 (Landsteiner and Wiener Blood System)
- BCAM = Basal cell adhesion molecule (Lutheran blood group)
Structural proteins
• Establish linkages with skeletal proteins
• Regulating cohesion
• Ankyrin-based macromolecular complex
• Protein 4.1R-based macromolecular complex
– Protein 4.1 (Beatty's Protein)
– Glycophorins C and D (Gerbich Blood Group)
– XK (Kell blood group precursor) (Kell Blood Group)
– RhD/RhCE (Rh Blood Group)
– Duffy antigen/chemokine receptor (DARC)
– Alpha-adducin
– Dematin
Erythrocyte exceptions
They lack organelles
• no ATP production in oxidative phosphorylation
• no ability to replace damaged lipids and proteins (low metabolic activities,
with no ability to synthesize new proteins or lipids)
Free radicals exposure
• haemoglobin autoxidation (O2
•- release)
• a cell membrane rich in polyunsaturated fatty acids (susceptible to lipid
peroxidation)
• deformation in tiny capillaries; catalytic ions leakage (cause of lipid
peroxidation)
ERYTHROCYTE METABOLISM AND THEIR SPECIAL
FEATURES
Glycolysis as a source
of ATP and 2,3-BPG
(90% of Glu
consumption)
They lack organelles
(practically zero ability to
regenerate, no proteosynthesis)
Exposure to ROS
(hemoglobin autooxidation, Ery deformation as
a source of ROS, lipid peroxidation)
Pentose pathway as
a source of NADPH
(10% Glu
consumption)
Synthesis of GSH
(up to 2mM conc., GSH /
GSSG, GR - antioxidant
system)
Carbonic
anhydrase I and II
(CA I and II –
interconversion of
CO2 a HCO3
-)
ATP as a
vasodilator
Erythrocyte metabolism
1. Glucose as a source of energy
(GLUT1 transporter, insulin-independent)
2. Glycolysis generates ATP and 2,3bisphosphoglycerate
(the specific binding
of 2,3-BPG to deoxyhemoglobin decreases
the oxygen affinity of hemoglobin and
facilites oxygen release in tissues)
3. The pentose phosphate pathway
produces NADPH
4. Glutathione synthesis - the
antioxidant defence system
Sprague RS, Stephenson AH, Ellsworth ML: Red not dead: signaling in and from
erythrocytes. TRENDS in Endocrinology and Metabolism 2007, 18(9):350-355.
Poikilocytes – drop-like erythrocytes
Schizocytes – fragmented erythrocytes
Spherocytes – volume normal, diameter smaller, thickness bigger
Eliptocytes – ecliptic shape
Leptocytes – thin, centrally concentrated haemoglobin
(thalasemia, after splenectomy)
Akantocytes – prickly prominences
MORPHOLOGICAL VARIATIONS OF ERYTHROCYTES
FRAGILITY OF ERYTHROCYTES
Haemolysis – destruction of red blood cell membrane.
Types of haemolysis:
a) physical
b) chemical
c) osmotic
d) biological (toxic)
e) immunological
Spherocytosis
- disorders of protein net responsible for shape and elasticity of
erythrocyte membrane – actin, ankyrin, spectrin.
Disorders of glucose-6-phosphate-dehydrogenase .
Erythrocytes life span: 120 days, role of lien (double circulation), splenectomy.
Reticulocytes.
Gallagher PG: Abnormalities
of the Erythrocyte
Membrane. Pediatric Clinics
of North America 2013,
60(6):1349-+.
Sedimentation rate indirectly corresponds to suspension stability of
blood.
Method of Fahreus-Westergren (FW).
Physiological values: men – women
Units: mm/10min, 1 hr, 2 hrs, 24 hrs
Physiological causes of increased sedimentation.
Pathological causes of increased sedimentation.
ERYTHROCYTE SEDIMENTATION
Silverthorn, D. U. Human Physiology – an Integrated Approach. 6th. edition. Pearson Education, Inc.
2012.
HAEMOGLOBIN
Red pigment transporting oxygen.
Protein, 64 450, 4 subunits.
Hem – derivative of porphyrine containing iron, conjugated with
polypeptides (globin).
Embryonic haemoglobin: Gower I a Gower II (t2e2, a2e2),
Portland
Fetal haemoglobin: Hb F, b2g2, weaker binding of 2,3 DPG
Adult haemoglobin: Hb A, a2b2 (141/146)
Forms of haemoglobin:
oxyhaemoglobin - O2
carbaminohaemoglobin – CO2
methaemoglobin – Fe3+ in hem
carboxyhaemoglobin – CO
Silverthorn, D. U.
Human Physiology –
an Integrated
Approach. 6th.
edition. Pearson
Education, Inc. 2012.
Abnormalities of haemoglobin production
•haemoglobinopathy (abnormal structure of chains)
•thalasemia (lower production of normal chains)
•Sickle cell anaemia (Hb J)
Synthesis and destruction of haemoglobin
Hem: glycin a succinyl-CoA
Globin: AMK
Hem - globin: biliverdin, bilirubin (lumirubin – photo-therapy), bil
Clinical aspects - Glycosylated haemoglobin (HbA1)
• formed by hemoglobin's exposure to high plasma levels of glucose
• non-enzymatic glycolysation (glycation)- sugar bonding to a protein
• normal level HbA1- 5%; a buildup of HbA1- increased glucose concentration
• the HbA1 level is proportional to average blood glucose concentration over
previous weeks; in individuals with poorly controlled diabetes, increases in
the quantities of these glycated hemoglobins are noted (patients
monitoring)
Sugar CHO + NH2 CH2 Protein
Sugar CH N CH2 Protein
Sugar CH2 NH CH2 Protein
Schiff base
Glycosylated protein
Amadori reaction
Glycoprotein, 39 000, a2-globulin.
Recombinant erythropoetin.
Small amount in plasma, urine, lymph, foetal blood.
Inactivation: liver
Origin: kidneys (85-90%) – endothelial cells of peri-tubular capillaries
in kidney core, liver (10-15%)
Stimulation of release: tissue hypoxia of any origin, alkalosis, cobalt
salts, androgens, catecholamines (b-receptors)
Effects:
Erythropoetin responsive cell – differentiation into erythroid line:
increase of synthesis of nucleic acids, increase of iron absorption
in erythroid cells, stimulation of cells release from bone marrow into
circulation
Acclimation – adaptation to high altitude
ERYTHROPOETIN
Thrombopoietin (THPO)
- Binding of TPO to R (c-Mpl) platelets
and megakaryocytes
- Internalization of receptors
- "Clearance" of TPO and reduction of
circulating TPO levels
- Constitutive production of TPO
- Decrease in platelet count = increase in
circulating TPO levels
- Platelet aging = desialylation
- Desialylation due to infection?
- "Detection" of Gal oligosaccharide
residues
- AMR receptor
Characteristics
- Glycoprotein
- Liver, kidneys (PCT), bone marrow,
skeletal muscle
ERYTHROPOESIS
Substances affecting erythropoesis
Need of copper
Ceruloplasmin – binding protein (a2-globulin) with ferroxidase activity. Oxidation of
Fe2+ to Fe3+ is necessary for binding of iron to transferrin.
Need of cobalt
Part of vitamin B12 molecule.
Vitamin B12 (cyancobalamin)
Produced by bacteria in GIT.
Source: liver, kidneys, meet, milk products…
Resorption: necessity of s.c. intrinsic factor secreted by parietal cells of gastric
fundus and body. Bound to transcobalamins in blood.
Stored in liver, pancreas, kidneys, brain, myocardium.
Function: synthesis of nucleic acids, co-factor in conversion of ribonucleotids to
deoxyribonucleotids, production of metabolic active forms of folic acid
NECESSARY FOR NORMAL DIVISION AND MATURATION OF RED BLOOD
CELL LINE ELEMENTS.
Symptoms of anaemia after years only!!!
Pernicious anaemia.
Folic acid (pteroylglutamic)
Produced by higher plants and micro-organisms.
Source: green vegetables, yeast, liver, kidneys…
Function: part of co-enzymes during synthesis of DNA, participation in cell
division and differentiation
Deficiency: deficient nutrition, treatment with cytostatics (methotrexate)
Symptoms of anaemia already after couple of months!!!
Macrocyte hyperchromic anaemia.
Other vitamins
Vitamin B6 (pyridoxine) – metabolism of amino acids, synthesis of hem
Vitamin B2 (riboflavin) – part of flavoprotein enzymes – reductases of
erythrocytes (normal function and survival of erythrocytes). Normocyte
anaemia with lower reticulocytes count.
Vitamin C (ascorbic acid) – non-specific function in erythropoesis.
Hormonal influences
Androgens, estrogens, hormones of thyroid gland, glucocorticoids, growth
hormone.
ANAEMIA
Disorder, in which basic and characteristic feature is lower amount
of haemoglobin. Usually also haematocrit and red blood cell count
in 1 litre of blood are below physiological value.
CLASSIFICATION OF ANEMIAS
MORPHOLOGICAL CLASSIFICATION
Evaluation of erythrocyte volume and concentration of
haemoglobin in erythrocytes
1. Normocyte anaemia
2. Microcyte a.
3. Macrocyte
1. Normochromic anaemia
2. Hypochromic a.
PATHOPHYSIOLOGICAL CLASSIFICATION
Anaemias caused by inefficient blood production
Sideropenic anaemias – lack of iron
Megaloblastic a. – lack of vitamin B12 or folic acid
Anaemias caused by suppression of blood production
Anaemias in chronic diseases and symptomatic anaemias
Thalasemia
Anaemias caused by increased losses
Haemolytic a.– caused by increased destruction of erythrocytes
Chronic posthaemorhagic anemia
Acute posthaemorhagic anaemia
ANTIGENS AND ANTIBODIES OF RED BLOOD CELLS
1) History of blood transfusions.
2) Posttransfusion reactions: aglutination, haemolysis (immediate or delayed), life-threatening
complications (jaundice, damage of kidneys, anuria, death – in case of full blood or RBCs
administration, in case of plasma – dilution of aglutinins!!!
Autoimmune diseases. Paternity tests, event. transplantology.
3) Antigens of blood cells:
a) 30 antigen systems (ABO, Rh, MNSs, Lutheran, Kell, Kidd, Lewis, Diego, P, Duffy…)
b) hundreds of other – „weak“ – antigens (important for paternity testing, organ transplantations)
4) Aglutinogen: antigen of plasmatic membrane of cells
- complex oligosaccharide
- erytrocytes, salivary glands, pancreas, liver, kidney, lungs, testes
- saliva, sperm, amnionic fluid, milk, urine
5) Aglutinin: antibody against aglutinogen, g-globulin (IgM –AB0 system, IgG – Rh system),
produced in the same way as other antibodies
- after births almost zero concentration in blood
- production of aglutinins begins 2-8 months after birth: stimulation by antigens similar to
aglutinogens – in food, in GIT bacteria
- maximal concentration of antibodies is reached in 8-10 years, decreases gradually with age
Blood group systems
A-B-O SYSTEM
Genotype Blood group Aglutinogen Aglutinin
00 0 (H) anti-A a
anti-B
0A or AA A A anti-B
0B or BB B B anti-A
AB AB A and B Described
by Landsteiner in 1901, 1930 – awarded by Nobel Price.
Janský -1906.
Frequency of blood groups in ABO system:
O 47% (38%)
A 41% (42%)
B 9% (14%)
AB 3% (6,5%)
Subgroups in A a B blood groups.
A1 (1 million copies of antigen on 1 ery), A2 (250 thousands copies).
Heredity: both A and B is inherited dominantly, according to Mendel´s law.
Rh SYSTEM
Monkey Maccacus rhesus.
40th of the 20th century, Wiener a Landsteiner.
Frequency: 85% - Rh+, 15% - Rh-.
Antigens D, C, E, d, c, e. Present only on erythrocytes.
D – the „strongest“ antigen: Rh – positive, Rh – negative (produces
anti-D aglutinin after contact with D-erythrocytes).
Aglutinins production: only after the contact with D-erythrocytes
(transfusion, foetal erythroblastosis).
High concentration of anti-D antibodies lasts for many years!!!
HAEMOLYTIC JAUNDICE OF NEWBORNS
Rh-negative mother x Rh-positive foetus.
First pregnancy – immunisation of mother during delivery (or interruption or miscarriage!!!).
Next pregnancy – anti-D aglutinins (IgG) cross foetoplacental barrier.
Foetus damage: approx. in 17% of next pregnancies
Haemolysis of foetal erythrocytes – haemolyti disease of newborn (erythroblastosis fetalis):
•anaemia
•jaundice
•oedemas – event. hydrops fetalis
•CNS damage (icterus) –bile acids enter CNS (no haematoencephalic barrier!)
•deaths of foetus in utero
Prevention of foetal damage:
1) administration of small doses of anti-D antibodies to mother during pregnancy
2) administration of one dose of anti-D antibodies during postpartum period
Success of therapy: up 90%.