Physiology of Blood
Blood Clotting
doc. MUDr. Markéta Bébarová, Ph.D.
Blood Functions
 homeostatic function
 transport function
 humoral regulation
 immune defence
 blood clotting
‐ thermoregulation
‐ buffering
‐ blood gases
‐ nutrients, metabolites, 
vitamins
‐ hormones
‐ heat, etc.
https://www.rd.com/health/healthcare/why‐is‐
blood‐red/
Blood Composition
https://www.123rf.com/photo_39782091_blood‐
composition.html
 complex fluid consisting of plasma
(extracellular fluid rich in proteins) 
and of formed elements (RBCs, 
WBCs, platelets)
 suspension of formed elements in plasma
 total blood volume: ‐ adult man 80 ml/kg body weight
‐ adult woman 70 ml/kg body weight
 hematocrit ‐ fraction of the
total column occupied by RBCs; 
measure of concentration!
‐ adult man 45%
‐ adult woman 40%
‐ newborn 55%, infant 32%
(6‐8% of total body mass)
Blood Composition ‐ Plasma
 watery solution composed
of:
‐ water (90‐92%)
‐ electrolytes ( 1%)
‐ plasma proteins (7‐8%)
‐ nutrients
(carbohydrates, lipids, 
aminoacids)
‐ gases (O2, CO2)
‐ waste products
(urea, uric acid, etc.)
‐ others
(hormones, vitamins, etc.)
http://encyclopedia.lubopit
ko‐
bg.com/Composition_and_
Functions_of_Blood.html
 serum – residual fluid after
blood clotting
Blood Composition ‐ Plasma
Guyton  Hall. Textbook of Medical Physiology
Blood Composition – Formed Elements
elements / µl
LEUKOCYTES  (WBCs) 3600 ‐ 9600
GRANULOCYTES
neutrophiles 3000 ‐ 6000
eozinophiles 150 ‐ 300
basophils 0 ‐ 100
AGRANULOCYTES
lymphocytes 1200 ‐ 3400
monocytes 110 ‐ 590
ERYTHROCYTES  (RBCs)
man 4.5 – 6.3 . 106
woman 4.2 – 5.4 . 106
THROMBOCYTES  (platelets) 140000 – 440000
White Blood Cell Count %
GRANULOCYTES
neutrophiles 50 ‐ 70
eozinophiles 1 ‐ 4
basophils  1
AGRANULOCYTES
lymphocytes 20 ‐ 40
monocytes 2 – 8
Blood Composition – Formed Elements
https://www.cancer.gov/publications/dictionaries/cancer‐terms/def/bone‐marrow
 Hematopoesis
‐ medullar
adult – bone marrow
‐ extramedullar
children – liver, spleen
Blood Composition – Formed Elements
 Hematopoesis
https://commons.wikimedia.org/wiki/File:2204_The_Hematopoietic_System_of_the_Bone_Marrow_new.jpg
Blood Composition – Formed Elements
elements / µl
LEUKOCYTES  (WBCs) 3600 ‐ 9600
GRANULOCYTES
neutrophiles 3000 ‐ 6000
eozinophiles 150 ‐ 300
basophils 0 ‐ 100
AGRANULOCYTES
lymphocytes 1200 ‐ 3400
monocytes 110 ‐ 590
ERYTHROCYTES  (RBCs)
man 4.5 – 6.3 . 106
woman 4.2 – 5.4 . 106
THROMBOCYTES  (platelets) 140000 – 440000
White Blood Cell Count %
GRANULOCYTES
neutrophiles 50 ‐ 70
eozinophiles 1 ‐ 4
basophils  1
AGRANULOCYTES
lymphocytes 20 ‐ 40
monocytes 2 – 8
Red Blood Cells (Erythrocytes)
https://www.rd.com/health/health
care/why‐is‐blood‐red/
 diameter 7.5 µm, thickness 2 µm; volume 90 fl (normocytes) 
Price‐Jones curve
microcytes (‐osis)  6 µm,  80 fl; macrocytes (‐osis)  8.2 µm,  95 fl
anizocytosis (physiological vs. pathological)
 lack of organelles
Red Blood Cells (Erythrocytes)
https://www.rd.com/health/health
care/why‐is‐blood‐red/
 biconcave discs
 diameter 7.5 µm, thickness 2 µm; volume 90 fl (normocytes) 
OPTIMAL SURFACE TO VOLUME RATIO
DEFORMATION IN CAPILLARIES 
(Fahraeus‐Lindqvist effect)
microcytes (‐osis)  6 µm,  80 fl; macrocytes (‐osis)  8.2 µm,  95 fl
anizocytosis (physiological vs. pathological)
poikilocytosis – abnormal shape of erythrocytes
spherocytes – spheric erythrocytes
eliptocytes – eliptic erythrocytes
schizocytes – fragmented erythrocytes
etc.
 lack of organelles
Red Blood Cells (Erythrocytes)
‐ red pigment transporting oxygen
‐ 4 protein subunits (globin)
‐ hem – derivative of porphyrine
containing iron, conjugated with
globin
 Hemoglobin
http://cubocube.com/dashboard.php?a=1190&b=1304&c=103
 HbA (adult; 22)
 HbF (fetal; 22)
weaker binding of 2,3‐DPG, thus, 
higher affinity to oxygen
Red Blood Cells (Erythrocytes)
‐ oxyhemoglobin (O2)
‐ carbaminohemoglobin (CO2)
 Hemoglobin derivatives
‐ carboxyhemoglobin (CO)
‐ methemoglobin (Fe3+ in hem)
‐ glycosylated hemoglobin (HbA1) – physiologically  5%
HbA1 level proportional to glucose plasma concentrations in previous 
weeks ‐ monitoring of diabetes in clinical practise
Red Blood Cells (Erythrocytes)
parameter man woman
hematocrit (Hct; %) 42 ‐ 52 37 ‐ 47
erythrocytes (RBC; 106/µl) 4.5 – 6.3 4.2 – 5.4
hemoglobin (Hb; g/l) 140 ‐ 180 120 ‐ 160
parameter man woman
mean corpuscular volume
(MCV; fl)
= HCT / RBC 80 ‐ 95 80 ‐ 95
mean content of hemoglobin 
(MCH; pg)
= Hb / RBC 27 ‐ 32 27 ‐ 32
mean corpuscular hemoglobin 
concentration (MCHC; g/1 ml)
= Hb / Hct 310 ‐ 360 310 ‐ 360
erythrocytopenia (oligocytopenia) ‐ normocytemia – polyglobulia (polycytemia) 
anemia
hypochromia – euchromia ‐ hyperchromia
Red Blood Cells (Erythrocytes)
 Anemia
‐ disease characterized by a decreased amount of hemoglobin
‐ Hct and RBC are usually lower as well but not in all cases!
Morphological classification
Pathophysiological classification
1. Normocyte a.
2. Microcyte a.
3. Macrocyte a.
1. Normochromic a.
2. Hypochromic a.
3. Hyperchromic a.
A) RBC size: B) RBC Hb content:
1. sideropenic a. (lack of iron)
2. megaloblastic a. (lack of vitamin B12 or folic acid)
3. a. due to suppresion of hemopoesis
4. symptomatic a. (secondary to a primary disease)
5. thalasemia
A) anemia caused by inefficient hemopoesis:
Red Blood Cells (Erythrocytes)
 Anemia
‐ disease characterized by a decreased amount of hemoglobin
‐ Hct and RBC are usually lower as well but not in all cases!
Morphological classification
Pathophysiological classification
1. Normocyte a.
2. Microcyte a.
3. Macrocyte a.
1. Normochromic a.
2. Hypochromic a.
3. Hyperchromic a.
A) RBC size: B) RBC Hb content:
B) anemia caused by an increased loss
1. acute and chronic posthemorhagic a.
2. hemolytic a.
A) anemia caused by inefficient hemopoesis:
Red Blood Cells (Erythrocytes)
 Hemoglobin erythrocyte life span: 120 days
Red Blood Cells (Erythrocytes)
 Hemolysis
‐ destruction of membrane of erythrocyte
‐ physical
‐ chemical
‐ osmotic
‐ toxic (biological)
‐ immunological
Red Blood Cells (Erythrocytes)
https://www.123rf.com/photo_39782091_blood‐
composition.html
 Erythrocyte sedimentation rate
https://www.syl.ru/article/170503/new_skorost‐
osedaniya‐eritrotsitov‐norma‐chto‐oznachaet‐skorost‐
osedaniya‐eritrotsitov
Red Blood Cells (Erythrocytes)
 Erythrocyte sedimentation rate
‐ indirectly proportional to the suspension stability of
erythrocytes (Helmholtz bilayer, zeta potential)
https://openi.nlm.nih.gov/detailedresult.php?img=P
MC3415751_rbhh‐33‐297‐g05&req=4
https://www.labce.com/spg8
13211_zeta_potential_and_v
an_der_waals_forces.aspx
Red Blood Cells (Erythrocytes)
 Erythrocyte sedimentation rate
https://www.sysmex.cz/media‐
center/rouleaux‐formation‐5493.html https://en.wikipedia.org/wiki/F
ile:Gray453‐ab.png
‐ indirectly proportional to the suspension stability of
erythrocytes (Helmholtz bilayer, zeta potential)
Red Blood Cells (Erythrocytes)
 Erythrocyte sedimentation rate
https://www.syl.ru/article/170503/new_skorost‐
osedaniya‐eritrotsitov‐norma‐chto‐oznachaet‐skorost‐
osedaniya‐eritrotsitov
Fahraeus‐Westergren
method (FW)
man 2‐8 mm/hour
woman  7‐12 mm/hour
physiological vs. pathological
increase
‐ size and number of RBCs
‐ fibrinogen
‐ immunoglobulins
main factors affecting ESR:
Blood Composition – Formed Elements
 Hematopoesis
https://commons.wikimedia.org/wiki/File:2204_The_Hematopoietic_System_of_the_Bone_Marrow_new.jpg
 Erythropoesis
‐ stimulated by 
erythropoetin
Erythropoesis
 Erythropoetin
‐ glycoprotein, 2‐globulin
‐ 85‐90% originates in the kidney (endothelial cells of
peritubular capillaries in the kindey medulla)
‐ 10‐15 % originates in the liver
‐ synthesis and release stimulated by tissue hypoxia of any
origin (adaptation to high altitude), alkalosis, androgens, 
catecholamines (‐rec.), etc.
‐ many other functions, such as regulation of bone formation and repair, 
muscle regeneration and hypertrophy, angiogenesis, neuroprotection
(neurotrophic factor), etc.
Erythropoesis
 Vitamin B12 (cyancobalamin)
‐ produced by bacteria in GIT
‐ ingested ‐ sources: liver, kidneys, meet, milk products, etc.
‐ the intrinsic factor (secreted by parietal cells of the stomach) is
necessary for its resorption in the ileum
‐ transport in blood – bound to transcobalamin
‐ necessary for normal division and maturation of red blood cell 
line elements
‐ symptoms after long‐term 
deficiency – pernicious anemia
Blood Composition – Formed Elements
elements / µl
LEUKOCYTES  (WBCs) 3600 ‐ 9600
GRANULOCYTES
neutrophiles 3000 ‐ 6000
eozinophiles 150 ‐ 300
basophils 0 ‐ 100
AGRANULOCYTES
lymphocytes 1200 ‐ 3400
monocytes 110 ‐ 590
ERYTHROCYTES  (RBCs)
man 4.5 – 6.3 . 106
woman 4.2 – 5.4 . 106
THROMBOCYTES  (platelets) 140000 – 440000
White Blood Cell Count %
GRANULOCYTES
neutrophiles 50 ‐ 70
eozinophiles 1 ‐ 4
basophils  1
AGRANULOCYTES
lymphocytes 20 ‐ 40
monocytes 2 – 8
Thrombocytes (Platelets)
‐ the smallest formed elements
(diameter 2‐4 µm, thickness 0.5‐1 µm, 4‐8 fl)
‐ smooth, round discs
‐ nucleus‐less, colorless, granulated
‐ fragments of megakaryocytes
‐ 1/3 in the spleen, 2/3 in the peripheral
blood (thrombocytosis after splenectomy)
‐ life span: 9‐ 12  days, biological halftime 
4 days
https://www.researchgate.net/publica
tion/283465115_Effects_of_Methadon
e_Exposure_during_Development_on_
Avian_Brain_and_Blood_Cells/figures?
lo=1
Thrombocytes (Platelets)
‐ membrane contains glycoprotein
receptors for adhesion to surfaces
(collagen, fibrinogen, von Willebrand factor)
‐ cytoplasm contains actin, myosin, 
glycogen, lysozomes and granules
https://oncohemakey.com/platelet‐structure‐
and‐function‐in‐hemostasis‐and‐thrombosis/
http://www.bloodjournal.org/content/108/8/25
87
1) dense granules (‐granules)
(non‐protein substances – calcium, 
serotonin, ADP, …)
2) ‐granules
(protein substances – clotting factors
such as vWF, factor V and XIII, PDGF, …)
‐ glycocalyx – 10 – 50 nm, mixture of
proteins and mucopolysaccharides
(clotting factors, ions, histamin, …) 
Thrombocytes (Platelets)
‐ key players in hemostasis
‐ keeping integrity of the vessel wall and 
healing of a ruptured vessel wall (PDGF)
‐ inflammatory reaction, changes in 
permeability of capillary wall, graft
rejection, …
‐ carriers of many substances absorbed to 
their surface
https://oncohemakey.com/platelet‐structure‐
and‐function‐in‐hemostasis‐and‐thrombosis/
http://www.bloodjournal.org/content/108/8/25
87
 Functions
Hemostasis
‐ reaction of vessels
‐ actions of platelets
‐ blood clotting
 set of mechanisms which prevent and stop bleeding
 three main processes:
https://www.firstaidforfree.com/what‐are‐the‐different‐
types‐of‐bleeding‐in‐first‐aid/
 balance between procoagulant and anticoagulant factors
to prevent/stop bleeding but also to prevent
intravascular clotting!  (thrombosis, risk of embolism)
Hemostasis (white clot)
‐ myogenic contraction
(direct damage)
‐ serotonin, 
thromboxan A2 
(platelets)
‐ endothelin 1
(endothelial cells; 
thrombin, fibrinogen)
‐ epinephrine (pain)
‐ fibrinopeptides
 reaction of vessels ‐ vasoconstriction
 the extent of vasoconstriction depends on the severity of vascular
injury
https://www.firstaidforfree.com/what‐are‐the‐different‐
types‐of‐bleeding‐in‐first‐aid/
Hemostasis (white clot)
‐ vasoconstriction ‐ serotonin, thromboxan A2 
‐ formation of plug
‐ blood clotting (clotting factors in ‐granules) 
 actions of platelets
 adhesion
 activation
 aggregation
Hemostasis (white clot)
 actions of platelets
 adhesion
https://courses.washington.edu/conj/bloodcells/platelets.htm
‐ impaired endothelium – collagen, fibronectin, laminin
(components of the subendothelial matrix) – platelet membrane
receptors (glycoproteins, integrins)
‐ von Willebrand factor (vWF) released from endothelial cells and 
from ‐granules of thrombocytes (high shear stress, certain cytokines, hypoxia)
Hemostasis (white clot)
 actions of platelets
 adhesion
 activation
https://courses.washington.edu/conj/bloodcells/platelets.htm
‐ degranulation: dense granules – serotonin (5‐HT), Ca2+, ADP, …
‐granules – vWF, clotting factor V, fibrinogen, 
growth factors (PDGF), …
thromboxan A2 (TXA2; cyclooxygenase)
‐ morphological
changes
(swelling, 
pseudopodia)
vasoconstriction (5‐HT, TXA2)
stimulation of adhesion (vWF), 
activation and aggregation (ADP, PAF)
mitogenic effects (PDGF)
dense granules – serotonin (5‐HT), Ca2+, ADP, …
‐granules – vWF, clotting factor V, fibrinogen, 
growth factors (PDGF), …
thromboxan A2 (TXA2; cyclooxygenase)
Hemostasis (white clot)
 actions of platelets
 adhesion
 activation
‐ degranulation:
‐ morphological
changes
(pseudopodia)
vasoconstriction (5‐HT, TXA2)
stimulation of adhesion (vWF), 
activation and aggregation (ADP, PAF)
mitogenic effects (PDGF)
https://www.researchgate.net/publicat
ion/308050751_Dual_antiplatelet_ther
apy_for_acute_coronary_syndromes_H
ow_long_to_continue/figures?lo=1
Hemostasis (white clot)
 actions of platelets
 adhesion
 activation
 aggregation
https://www.researchgate.net/publicat
ion/308050751_Dual_antiplatelet_ther
apy_for_acute_coronary_syndromes_H
ow_long_to_continue/figures?lo=1
‐ activation of additional platelets
(ADP, 5‐HT, TXA2) promotes their
aggregation
‐ molecular bridges between
platelets: von Willebrand factor
(vWF), fibrinogen
Hemostasis (white clot)
 actions of platelets
 adhesion
 activation
 aggregation
‐ activation of additional platelets
(ADP, 5‐HT, TXA2) promotes their
aggregation
‐ molecular bridges between
platelets: von Willebrand factor
(vWF), fibrinogen
https://www.youtube.com/watch?v=WFa1x6‐ufTg
 white clot
Hemostasis
Hemostasis (red clot)
 blood clotting
Hemostasis (red clot)
 blood clotting
https://doctorlib.info/physiol
ogy/medical/101.html
surface contact activation
tissue factor activation
Hemostasis (red clot)
 fibrinolysis
https://www.researchgate.net/pu
blication/284136686_Data_Supp
orting_the_Structural_and_Functi
onal_Characterization_of_Throm
bin‐
Activatable_Fibrinolysis_Inhibitor
_in_Breast_Cancer/figures?lo=1
tPA – tissue plasminogen activator
uPA – urokinase plasminogen activator
PAI‐1, PAI‐2 – plasminogen activator inhibitors
TAFI – thrombin‐activatable fibrinolysis inhibitor
streptokinase
Hemostasis (red clot)
 clotting is counteracted by anticoagulating mechanisms
‐ endothelium
‐ blood stream
‐ TXA2 vs.
prostacycline
a) non‐humoral control
‐ antithrombin III
‐ fibrin
‐ thrombomodulin
‐ protein C (Ca)
‐ protein S
‐ plasmin
‐ TFPI
b) humoral control
Hemostasis ‐ Summary
Hemostasis – Endothelial Cells
Intravascular Coagulation
 caused by damage of endothelium due to:
‐ atherosclerosis (myocardial infarction, stroke) 
‐ inflammation (venous thrombosis, pulmonary embolism)
 antithrombotic drugs
https://slideplayer.com/slide/8138006/
https://step2.medbullets.com/heme/121681/anticoagulants
https://www.researchgate.net/p
ublication/284136686_Data_Su
pporting_the_Structural_and_Fu
nctional_Characterization_of_Th
rombin‐
Activatable_Fibrinolysis_Inhibito
r_in_Breast_Cancer/figures?lo=1
tPA – tissue plasminogen activator
uPA – urokinase plasminogen activator
PAI‐1, PAI‐2 – plasminogen activator inhibitors
TAFI – thrombin‐activatable fibrinolysis inhibitor
streptokinase
Blood Clotting Testing
 bleeding time, clotting time
 prothrombin time
 activation partial thromboplastin time
https://cz.pinterest.com/pin/
175077504249510600/
Blood Clotting Testing
 bleeding time, clotting time
 prothrombin time
 activation partial thromboplastin time
Blood Clotting Testing
 bleeding time, clotting time
 prothrombin time
https://bpac.org.nz/BT/2010/November/inr.aspx
Coagulation Disorders
 blood clotting starts either spontaneously or after
inadequately small stimulus, or blood clotting blunted
‐ diseases of vessels
‐ platelet disorders (thrombocytopenia, thrombocytopathy)
‐ coagulopathies
a) disorders of synthesis of clotting factors (e.g. hemophilia, 
hypovitaminosis K, therapy with coumarin derivatives)
b) disorders of metabolism of clotting factors (e.g. consumptive
coagulopathy, hyperfibrinolysis, therapy by heparin, repeated
transfusions)