HAEMOSTASIS COAGULATION OF BLOOD

HAEMOSTASIS - I
DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
DEPT. OF PHYSIOLOGY

OBJECTIVES
 Haemostasis
 Blood coagulation
 Anti-haemostatic
mechanism
 Bleeding disorders.
 Laboratory tests.
Saturday, May 14, 2016

HAEMOSTASIS
 Definition – spontaneous arrest or stoppage of bleeding
from injured blood vessel by physiological process.
 3 processes
 Vasoconstriction
 Formation of temporary haemostatic plug formation
 Formation of Definitive haemostatic plug formation

VASOCONSTRICTION
 Immediate –
 Direct effect of injury
 Proportionate to the
degree of trauma.
 Later by humoral
 Release of 5- HT by
bound platelets to the
collagen

FORMATION OF TEMPORARY
HAEMOSTATIC PLUG FORMATION
 Platelet adhesion
 Platelet activation
 Platelet aggregation
 Formation of
temporary
haemostatic plug
 Inhibition of further
plug formation.

PLATELET ADHESION
 After injury platelets
contacts with collagen &
damaged endothelium
 Swell, becomes irregular &
protrudes Pseudopodia.
 Contractile proteins contracts
& releases granules.
 Platelets becomes sticky &
adhere to collagen.

PLATELET ACTIVATION
 Platelets secretes
 ADP & Thromboxane
A2
 Activates other
platelets & cycle
continues

PLATELET AGGREGATION
 Activated sticky
platelets stick to each
other & forms
Aggregation
 It is also increases by
Platelet Activating
Factor (PAF) released
by neutrophils,
Monocyte & platelets
cell membrane lipids.

FORMATION OF TEMPORARY
HAEMOSTATIC PLUG
 Platelet Adhesion
 Platelet Aggregation
 Fairy Loose Plug

INHIBITION OF FURTHER
PLUG FORMATION.
 Prostacycline from
membrane
phospholipids
 Inhibit Thromboxane
formation

FORMATION OF DEFINITIVE
HAEMOSTATIC PLUG FORMATION
 Temporary plug
converted to definitive
plug by Process of
blood coagulation.
 Results in formation of
tight unyielding seal

COAGULATION OF BLOOD
 Through out life blood – in
fluid state but when
removed or shed or
collected in container
become jelly like – clot
 Fluidity – necessary for
circulation.
 Coagulation – protect
from excessive bleeding.

COAGULATION OF BLOOD
 Clotting factors
 Mechanism of coagulation
 Role of calcium in blood coagulation.
 Role of vitamin –k, liver and vascular wall in
haemostasis and coagulation.
 Blood clot retraction
 Blood in fluid state
 Thrombosis

CLOTTING FACTORS
 I – FIBRINOGEN
 Soluble
 Mol wt – 3,40,000
Dalton
 6 polypeptide chain
 Conc. – 0.3 gm/100 ml
 It is converted into
fibrin in the presence of
enzyme thrombin

CLOTTING FACTORS
 II- PROTHROMBIN
 Inactive precursor of
thrombin.
 Mol wt 69000 dalton.
 Synthesized in liver in
the presence of vitamin
K.
 Conc. is 40 mg / 100
ml.

CLOTTING FACTORS
 III – THROMBOPLASTIN
 Also called tissue factor or tissue thromboplastin
 Released in extrinsic pathway.

CLOTTING FACTORS
 IV – CALCIUM
 Essential in all stages of coagulation.

CLOTTING FACTORS
 V – LABILE FACTOR / PROACCLERIN
 Required for formation of protrombin activator
 Consumed during clotting so absent in serum.

CLOTTING FACTORS
 VII – STABLE FACTOR / PROCONVERTIN
 For activation of factor X in extrinsic pathway.

CLOTTING FACTORS
 VIII – ANTI-HAEMOPHYLLIC FACTOR A / ANTI-
HAEMOPHLIC GLOBULIN.
 Protein of b globulin type, synthesized in liver.
 Activation of factor x
 Deficiency causes classical Haemophilia.
 Inherited disease in which CT prolonged.

CLOTTING FACTORS
 IX – ANTI-HAEMOPHILIC FACTOR B/ PLASMA
THROMBOPLASTIC COMPONENT
 First discovered in patient named Christmas.

CLOTTING FACTORS
 X –STUART-PROWER FACTOR
 Along with active factor V, Ca and phopholipid forms a
complex – Prothrombin activator.
 Formed in both extrinsic & intrinsic pathway.

CLOTTING FACTORS
 XI – PLASMA THROMBOPLASTIN
ANTICEDENT / ANTI-HAEMOPHILIC FACTOR C
 Its deficiency causes hemorrhagic state.

CLOTTING FACTORS
 XII – HAGEMAN FACTOR/ GLASS FACTOR /
CONTACT FACTOR
 Activated when comes in contact with electronegative
surface or glass or rough surface.
 Its activation initiate intrinsic pathway.

CLOTTING FACTORS
 XIII – FIBRIN STABILIZING FACTOR /
FIBRINASE / LAKI LORAND FACTOR
 Required for activation of fibrin polymer along with Ca.

MECHANISM OF COAGULATION-
INTRINSIC PATHWAY.

EXTRINSIC PATHWAY.

DIFFERENCE .
 INTRINSIC
PATHWAY.
 Begins in blood itself.
 Much slower take 2-6
min.
 Initiated by activation
of factor XII.
 EXTRINSIC
PATHWAY.
 Begins with trauma to
the vascular wall or
tissue outside the
vessel wall.
 Explosive in nature
takes 15 sec.
 Initiated by activation
of factor III.

CONVERSION OF
PROTHROMBIN TO THROMBIN
 Prothrombin –
 Inactive precursor of
thrombin.
 Mol wt 69000 dalton.
 Synthesized in liver in
the presence of
vitamin K.
 Conc. is 40 mg / 100
ml.

THROMBIN.
Proteolytic enzyme.
Amount of thrombin
produced during
clotting of 1 ml of
blood is sufficient to
coagulate 3 liters of
blood.

I – FIBRINOGEN
 Soluble
 Mol wt – 3,40,000 Dalton
 6 polypeptide chain
 Conc. – 0.3 gm/100 ml
 It is converted into fibrin in the presence of enzyme
thrombin

FIBRINOGEN TO FIBRIN.
 Proteolysis
 Polymerization .
 Stabilization of fibrin polymers.

BLOOD CLOT RETRACTION.
 Clot is meshwork of fibrin
with entrapped blood cells ,
platelets & plasma.
 Contractile proteins – Actin,
myosin & thrombosthenin.
 Compress fibrin meshwork
squeeze out serum.
 Clot reduced to 40% of
original volume.

ROLE OF CALCIUM.
 Except for first 2 steps Ca required for all steps.
 Ca removal causes Anticoagulation.
 e.g. use of oxalates & citrates.

ROLE OF VITAMIN K.
 Chemical structure.
 Naphthoquinone derivatives.
 Fat soluble , insoluble in water.
 Sources.
 Food , bacterial flora.
 Role of vitamin K
 Synthesis of coagulants like Prothrombin.
 Factor VII , IX & X & circulatory anticoagulant
protein.

ROLE OF VITAMIN K.
 Deficiency causes serious hemorrhages.
 Its due to
 Obstructive jaundice
 Newborn babies.
 Chronic diarrhoea.
 Side effects of antibiotics.

ROLE OF LIVER.
 Synthesis of procoagulants – site of synthesis of
factor V,VII,IX,X, Prothrombin & fibrinogen
 Removal of activated procoagulants.
 Synthesis of anticoagulants like – heparin, anti
thrombin III & protein C

ROLE OF BLOOD VESSELS.
 Endothelium
 Anticoagulant role.
 Barrier.
 Produces heparin & α-2
macroglobulin.
 Smoothness prevent
aggregation.
 Produces PGI2 prevent
aggregation.

ROLE OF BLOOD VESSELS.
 Coagulant role
 Von Willebrand factor
(VWF)
 Tissue factor.
 Plasminogen activator.
 Sub endothelial tissue –
collagen fibres
 Causes platelet
aggregation
 Intrinsic pathway
activation.

BLOOD IN FLUID STATE
 Velocity of circulation.
 Surface effect of
endothelium.
 Glycocalyx
 Circulatory
anticoagulants.
 Fibrinolytic mechanism.
 Removal of activated
clotting factors.

VELOCITY OF CIRCULATION.
 Blood is in constant motion due to pumping by
heart & at constant velocity
 Decrease in velocity
 Intravascular clotting

SURFACE EFFECT OF ENDOTHELIUM.
GLYCOCALYX
 Endothelial lining smoothness – prevents adhesion
& intrinsic mechanism.
 Glycocalyx --inner layer of endothelium negatively
charged repel clotting factors &Y platelets &
prevent clotting.
 Intact Endothelium – barrier between collagenous
tissue & blood

CIRCULATORY ANTICOAGULANTS.
 Natural anti-coagulant.
 Heparin
 Antithrombin-III
 Alpha 2 macroglobulin
 Protein C

FIBRINOLYTIC MECHANISM.
 Protein C
 Inactivates inhibitor of
TPA
 Increases Plasmin
formation
 Acts as Fibrinolytic

REMOVAL OF ACTIVATED
CLOTTING FACTORS.
 Liver plays an important role
 Removes activated clotting factors
 Prevents Intravascular Clotting

THROMBOSIS
 Def.– Intravascular
clotting of blood & clot
so formed is thrombus
 Thrombus – Def –
Solid mass formed in
the living heart or
blood vessel from the
constituents of blood.

THROMBOSIS
 Virchow’s triad which
predisposes to
thrombus formation.
 Predisposing factors
 Endothelial injury
 Alteration of blood flow
 Hypercoagulability of
blood

ENDOTHELIAL INJURY
 It occurs in
 Ulcerated plaques in
advanced
atherosclerosis,
 Haemodynamic stress in
HT
 Arterial diseases
 DM
 Hypercholesterolemia

ALTERATION OF BLOOD FLOW
 Turbulence / stasis blood
flow
 Platelet contact with
endothelium
 Initiate thrombosis
(especially venous
thrombosis in leg veins
after major operations)

HYPERCOAGULABILITY OF
BLOOD
 Increase Platelet count
& adhesiveness.
 Increase Coagulation
factors as fibrinogen,
prothrombin
factors,Via,VIIa,Xa
 Decrease coagulation
inhibitors – Antithrombin
III & fibrinogen
degradation product.

THROMBOGENESIS
 Adherence of platelets
 Activation of coagulation system
 Entanglement of RBC with WBC – so clot mass is
mainly formed by entangled RBC & WBC.

THROMBI
 Red - mainly venous
 Soft, red & Gelatinous
 White – mainly arterial
 Pale & firm
 Mixed or laminated –
consists of alternate
white & red Layers –
Lines Of Zahn.

EFFECTS OF THROMBI
 Ischemia and Infarction
 Clot in Intact vessel decrease blood supply (Ischemia)
 Cell death (Infarction)
 Thromboembolism
 Dislodged clot in distant vessel & block circulation
 Pulmonary & Cerebral Embolism

PREVENTION OF THROMBI
 Drugs – decrease platelet adhesion; Aspirin,
Dextran
 Anticoagulants – Heparin, Dicoumarol
 Intermittent compression or electrical
stimulation of calf muscle

Thank you.

HAEMOSTASIS COAGULATION OF BLOOD

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