Haemostasis Primary Plug Formation Coagulation(Clotting) Related Investigations Related Diseases Drugs Therapy Fibrinolysis

1. Name: Chanaka Lakshan
Student ID: BS/15/10/15
Facilitator: Dr.Ariff
Subject: Histology & Hematology
Stream: Biomedical Science

2. 1) Primary Plug Formation
2) Coagulation(Clotting)
3) Related Investigations
4) Related Diseases
5) Drugs Therapy
6) Fibrinolysis

3.  Immediately after the injury, blood vessel will constrict
 Then the primary plug forms in 3 steps;
 Adherence
• Sub endothelial collagen expose
• This makes the release of Von Willebrand Factor/VWF
• VWF induce conformational changes in platelets where they get adhesive
filaments
• VWF anchors platelets to the sub endothelial collagen by GP-1b receptors

4.  Activation
• Adherence makes activation
• Platelets release cytokines & chemical mediators via degranulation
 [ADP, VWF, thromboxane A2, platelet-derived growth factor
/PDGF, vascular endothelial growth factor /VEGF, serotonin, and
coagulation factors]
• VWF & ADP make nearby platelets adhere
• TXA2 – platelet activation/maintain vasoconstriction
• Serotonin – inflammatory mediator/vasoconstriction
• PDGF & VEGF – cell division
• Factor 5 & 8 – important in coagulation
• Activation of platelet factor-3 that acts as a binding site for cofactor 5 & 8
• Production of thrombin

5. Adherence- Joining of platelets to collagen.
Activation- Attracts additional platelets to damaged site.
Aggregation- Fibrinogen forms bridges between activated platelets to form a plug.
Aggregation
•Platelets join each other by fibrinogen interaction with GP 2b-3a receptors
•Formation of primary plug (/primary hemostasis)

6. Coagulation
 Clots form upon the conversion of Soluble fibrinogen to insoluble cross-linked fibrin, and its
addition to the platelet plug.
 Fibrin threads that act as mesh.
 The coagulation process is useful in closing up and maintaining the platelet plug on larger wounds.
 The release of Prothrombin allows for the formation of a thrombus, or clot, to form.
 Proteins in coagulation – prekallikrein [activation of factor 7], High molecular Wt. Kininogen
[support reciprocal activation of 12,11 & prekallikrein]
 Majority of coagulation factors are serine protease that circulate in inactive form
 They are needed to be activated to function
 Many are synthesized by liver [factor 2,7,9,10,5,1]
 Some need vit K to be synthesized [factors 2,7,9,10]
 Protein C will be activated by protein S where as Activated protein C will inhibit the activation of
factor 8 & 5

7. Series of reactions takes place
to give rise to insoluble fibrins
which involves in the
formation of the permanent
secondary clots.

8. Fibrinolytic
 Anticlotting Mechanisms are Activated.
 Allow Clot Disintegration and Repair Damaged Vessel.
 Prevents the blood clot from growing and becoming problematic.
 2 types;
1) Primary Fibrinolysis - Normal body process
2) Secondary Fibrinolysis - Breakdown of clots due to a medicine, a medical
disorder.
 Plasmin (an enzyme) cuts the fibrin mesh at various places forming
circulating fragments that are cleared by other proteases or by kidney and
liver .

9.  After the wound has healed, the fibrin itself is dissolved in a process known
as Fibrinolysis .
 Plasmin breaks up fibrin clots.
 It is activated from inactive Plasminogen by tissue Plasminogen activator (t-
PA) and urokinase.
 They are inhibited by Plasminogen activator inhibitor-1 and Plasminogen
activator inhibitor-2 (PAI-1 and PAI-2).
 Initially, Plasminogen activators are inhibited. Over time, endothelial cells
secrete tissue Plasminogen activators & dissolving the clot & structural
integrity of the blood vessel wall is restored.
 Blood coagulation and Fibrinolysis always occur simultaneously in the blood
stream.

10. Anticoagulation factors
1. Anti thrombin 3 – inactivates factor 10a & give –ve
feedback on thrombin
2. Prostacyclin from endothelial cells – convert ADP in
to products that inhibit platelet aggregation &
vasodilatation
3. Protein C [Vit K dependent zymogen which is produced
in liver] – inactivates factor 5a & 8a
4. Protein S [vit K dependent binding protein] – the co-
factor for protein C
5. Thrombin with endothelial cells [=thrombomodulin] –
activates protein C, inhibits thrombin, inactivates factor
5a & 8a

11. Related Ix
 Bleeding time – an evaluation on platelet function; normal : <6 min
 Platelet count – normal: 150000 – 400000 per ml
 Partial thromboplastin time/aPTT –
1. related to intrinsic pathway (factor 12, 11, 9, 8, 10, 5);
2. used for monitoring heparin therapy
3. normal: 30-50 s
4. Prolonged aPTT may be due to intrinsic factor deficiency, heparin therapy,
sepsis or presence of Ab against coagulation factors
 50/50 mixing study –
1. Patient’s plasma + normal plasma & checks for aPTT
2. If aPTT becomes normal: patient lacks intrinsic factors
3. If not: circulating anticoagulants or antibodies against intrinsic factors
 Prothrombin time/PT –
1. Related to extrinsic pathway (factor 2, 7, 5, 10)
2. Used in monitoring warfarin therapy
3. Normal : 12-13 s
4. Factors determining accuracy : factor deficiencies, anticoagulants, a
circulating inhibitor

12.  Fibrinogen level – normal 200-500 mg/dL
 ADP platelet aggregation
 Ristocetin aggregation test – for presence/activity of VWF;
 Ristocetin cofactor assay uses platelet-poor plasma (with vWF but no
platelets) and adds ristocetin and exogenous formalin-fixed platelets
which can passively agglutinate (but not actively "aggregate", as they
are dead). Formalin does not allow the extrinsic platelets to secrete
the vWF of their α-granules, and thus only the activity of the intrinsic
vWF is tested.
 Thrombin time/TT
1. Normal 20-30s
2. Measures 3rd stage of coagulation
3. Prolonged due to :
• presence of heparin
• presence of fibrin split products
• deficiency or abnormality of fibrinogen

13. Drugs
 Unfractioned heparin (thrombin, 10a)
1. Administered via continuous dnp
2. Can be given as injections for prophylaxis
3. Increase the risk of heparin induced thrombocytopenia
 Enoxaparin (10a)
1. Twice or once a day
2. Treatment as compared to warfarin
3. Improved mortality in cancer patients for DVT/deep vein thrombosis & PE/pulmonary
embolism
 Warfarin
1. Related to factor 2, 7, 9, 10, C & S [C & S are natural anticoagulants]
2. Oral vitamin K antagonist – blocks vit K, so liver can’t form coagulation factors which
are formed by it, clotting won’t occur
3. Affected by diet & medications
4. CHEAP
5. If overdosed bleeding occurs; hence vit K is administered

14. Bleeding Disorders
1) It is due to the inability of the body to perform
Hemostasis properly.
2) It is due to a problem with the body's blood clotting process.
3) These disorders can lead to heavy and prolonged bleeding
after an injury.
4) Abnormal bleeding both outside and inside the body.
5) Arises due to;
 - Defects in the blood vessels
 - Defects in the platelets
 - Deficiency of coagulation factors

15. Vascular causes of bleeding
disorders
 Congenital
Due to vascular malformations and connective tissue
problems.
Heriditory Hemorrhagic Telangietasia (thin blood vessels
walls lacking smooth muscles)
Ehlers-Danlos Syndrome
 Acquired
Caused due to external reasons. Occurs after birth.
scurvy (Vitamin C deficiency)
Henoch-Schonlein purpura (generalized
hypersensitivity vasculitis)

16. Platelet defects
 Defects in platelets leads to bleeding disorders due to reduced platelets or receptor problems.
Thrombocytopenia - Disorder in which decreased in number of platelets are present. Caused due to;
 Reduced platelet production in the bone marrow.
 Increased breakdown of platelets in the blood stream, spleen or liver
 Bleeding from small vessels
 Normal or increased bleeding time
 Increased destruction
(1) isoimmune thrombocytopenia
(2) idiopathic thrombocytopenic purpura (ITP)
(3) thrombotic thrombocytopenic purpura (TTP)
(4) drug reaction
(5) mechanical destruction
(6) hypersplenism
ITP
 easy bruising and bleeding after minor trauma [Rx- steroid & splenectomy]
Acute - children following viral infection, self limiting disease, plt turns out helpless
Chronic - adults (often premenopausal females)
 may be associated with other “autoimmune diseases”
 production of autoantibody against Pt’s own platelets
 removal of opsonized platelets
 decreased circulating platelet, but increased BM megakaryocytes
TTP
• abnormal platelet aggregation in microcirculation
• angiopathic hemolytic anemia
• fever
• transient neurologic deficits
• renal failure
Thrombocytopathy - Dysfunctioning of the platelets, which results in prolonged bleeding time.

17. Platelet Functional Abnormalities
congenital
1. Bernard-Soulier syndrome
 Von Willebrand factor (vWF) cannot join with the platelets
 defect in platelet membrane glycoprotein (GP Ib)
 defect in platelet adhesion
2. Glanzmann’s throbosthenia
 Defect in platelet membrane glycoprotein (GP IIb & IIIa)
 Defect in platelet aggregation
 Fibrin joining doesn’t take place
 Both are Autosomal Recessive

18. Platelet Functional Abnormalities
acquired
1. Aspirin
 Inhibits cyclooxygenase & suppression of TXA2
(thromboxane A2)synthesis
 Effect lasts for 72 hours
 Irreversibly Binds to the Platelet for its entire lifespan (7-10
Days)
2. Thrombocythemia
 Functionally abnormal platelets
 Occasionally seen in myeloproliferative disorders

19. Coagulation factor deficiency
1.congenital : single factor deficiency
a. sex-linked
1) Hemophilia A (Factor VIII def.)
2) Hemophilia B (Christmas disease, Factor IX def.)
b. autosomal dominant
1) Von Willebrand’s disease
c. autosomal recessive
2. acquired : multi-factor deficiency and clotting
abnormalities
1) Vitamin K deficiency
2) Severe liver disease

20. Hemophilia A (Factor VIII deficiency)
• Classic hemophilia
• 80-85%
• Bleeding into joints
• X linked inherited disorder
• The main symptom is haemarthrosis
Investigation
Increased aPTT
Normal bleeding time, plt, PT

21.  Hemophilia B (Christmas disease, Factor IX def.)
• 10-15%
• Less common than hemophilia A
• Sex-linked inheritance
 Investigation
 prolonged PTT
 Von Willebrand's disease
 Easy bruisability (no bleeding into joints)
 Unable to release VIII-vWF
 Autosomal dominant
 Usually diagnosed in childhood or young adults
 Investigation
 Increased bleeding time
 Normal plt, PT
 Normal or increased aPTT

22.  Vitamin K Deficiency (vitamin K dependent factors :
II, VII, IX, X)
Acquired disorder
Investigation
Increased PT
Normal bleeding time, plt
Normal or increased aPTT
 Severe Liver Disease (Factors synthesized in liver : II,
V, VII, IX, X, fibrinogen)
Investigation
 Increased PT, aPTT
 Normal bleeding time, plt

23. Disseminated Intravascular
coagulation (DIC)
 Proteins that control blood clotting becomes overactive
 Formation of blood clots in small vessels all over the body
 Occur as a secondary complication in a variety of diseases
 Obstruction of blood flow that leads to organ damage.
• There’re 2 types; acute & chronic
• Due to predominance of thrombin generation and consumption of coagulation factors, acute DIC
will increase the bleeding tendency
• Chronic & subacute DIC will increase the thrombotic tendency
underlying causes;
- Inflammation & Infection
- Release of tissue factor or thromboplastic substance
- Blood cancer
- Widespread endothelial injury
Investigation
Acute DIC: - prolongation of aPTT, PT and TT
- reduction of platelets, AT III and protein C
- decreased fibrinogen
- elevated fibrin degradation products
Chronic DIC: - aPTT and PT may be within normal ranges
- slightly decreased platelets
- elevated fibrin degradation products
Management
 Treating the underlying cause
 Replacement therapy such as platelet transfusion and fibrinogen transfusion
 Administration Heparin

24. Deep Vein Thrombosis
 Formation of blood clots in one/more of the deeps veins.
 Symptoms include pain, swelling and redness