2. HAEMOSTASIS
Refers to the complicated chemical interplay that
maintains blood viscosity, or thickness.
Blood disorders occur when haemostasis falls out
of balance.
If blood becomes too thin, it loses the ability to
form the blood clots that stop bleeding.
When blood becomes too thick, the risk of blood
clots developing within the blood vessels rises
creating a potentially life-threatening condition.
4. PLATELETS
Platelets are produced in bone marrow by a process known
as thrombopoiesis.
They are formed in the cytoplasm of the megakaryocyte (a
very large cell).
The cytoplasm of the megakaryocyte fragments at the edge
of the cell.
This is called platelet budding.
Megakaryocytes mature in about 10 days, from a large stem
cell, the megakaryoblast.
5. PLATELET NUMBERS
• Among all the formed elements, platelets are the
smallest.
They are estimated to be 150,000 –450,000 per cubic
mm.
• Their half life is around 10 days.
11. CLOT FORMATION
• Clot consists of a gel of fibrin and trapped
formed elements
• Clot closes cut vessel
• When clot separates from plasma, remaining
fluid is serum
• Clotting process called coagulation
13. CLOTTING FACTOR IN THE BLOOD
CLOTTING FACTOR SYNONYMS
Fibrinogen Factor I
Prothrombin Factor II
Tissue factor Factor II, tissue
thromboplastin
Calcium Factor IV
Factor V Proaccelerin, labile
factor, Ac-globulin
(AC-G)
Factor VII Serum prothrombin
conversion, accerator
(SPLA) Proconvertin
stable factor
14. Factor VIII Antihaemophilic factor (AHF)
Antihaemophilic globulin (AHG)
Factor IX Plasma thromboplastin
component (PTA); Christmas
factor, Antihaemophilic factor B
Factor X Stuart factor, stuart-prower factor
Factor XI plasma thromboplastin antecedent
(PTA), Antihaemophilic C
Factor XII Hageman factor
Factor XIII Fibrin stabilizing factor
Prekallikrein Fletcher factor
High molecular wt. Fitzgerald factor
Kininogen (HWWK)
Platelets
15. Blood clotting occurs in three stages
Stage 1.
Stage 2.
Stage 3.
Formation of prothrombinase
Formation of thrombin
Formation of fibrin plug (clot)
16.
17. BLOOD CLOTTING DIAGRAM
Several clotting factors released
from damaged tissues, vessel wall
and platelets
Prothrombinase
Ca2+
Prothrombin Thrombin
Fibrinogen Fibrin
(clot)
Thrombin
Ca2+
18. • Vitamin K needed to form four of
the clotting factors
• Within 30 minutes platelets begin to
retract the clot by pulling edges of
cut vessel together
19. FIBRINOLYSIS
Is the process where a fibrin clot, the product of
coagulation, is broken down.
Its main enzyme, plasmin, cuts the fibrin mesh at
various places, leading to the production of circulating
fragments that are cleared by other proteinases or by
the kidney and liver.
20. CLOT DISSOLVING
• As repair of a cut or damaged vessel proceeds,
a series of enzyme catalyzed reactions called
fibrinolysis slowly dissolves the clot
• An enzyme called tissue plasminogen
activator catalyzes the conversion of inactive
plasminogen enzyme to active plasmin
• Active enzyme catalyzes the dissolving of clot
23. INTRAVASCULAR CLOT
• Intravascular clot – clot within closed vessel
• Damaged vessel lining or slowing of blood flow
Platelets aggregate and release clotting factors
• Resulting clot called a thrombus
• Moving piece of the clot is an embolus
• Clot moves downstream and blocks smaller
vessel embolism
• May cut off blood supply to organ
24. ANTICOAGULANTS
• Chemicals that decrease or prevent blood clotting
are called anticoagulants
• Heparin is administered medically and it occurs
naturally in our bodies. It works by decreasing
thrombin production
• Coumadin (warfarin) is effective as a long-term
anticoagulant. It is an antagonist of vitamin K.
• EDTA and CPD are used in blood banks to keep
the donated blood from clotting. They both work
by tying-up and removing calcium.
26. Coagulation and Disease
Hemophilia
Cardiovascular Diseases
Key problem – clots block undamaged blood
vessels
Anticoagulants prevent coagulation
Keep platelets from adhering
Prevent fibrin coagulation
"Clot Busters": Prevent further clotting
Speed fibrinolysis
Limit tissue damage (heart, brain…)
27. HEMOPHILIA
–Inherited clotting disorder due to a deficiency in a clotting
factor.
–Hemophilia is perhaps the best known of the bleeding
disorders.
–Hemophilia is a genetic disorder caused by mutations of genes
on the X chromosome.
–Because the mutated gene is recessive, the majority of
hemophiliacs are male.
28. Von Willebrand's Disease
Von Willebrand's disease is the most common of
the inherited bleeding disorders, including
hemophilia.
Von Willebrand's disease affects up to one
percent of the population,
and may be found in both sexes (as opposed to
hemophilia, which primarily affects males).
Von Willebrand's factor is a protein that allows
platelets to form temporary plugs at sites of blood
vessel injury:
Defects in von Willebrand's factor, impair the
ability of platelet cells to 'cling' to an injury and
form a plug.
29. THROMBOCYTOPENIA
Thrombocytopenia occurs when platelet cells fall to
abnormally low levels, impairing coagulation.
Leukemia, lymphoma, and some other cancers are
known to cause thrombocytopenia.
Cases of thrombocytopenia have also occurred due to
heparin, a blood thinning medication.
30. LIVER DISORDERS
Liver cirrhosis interferes with the liver's ability to
produce vital proteins, including coagulation factors.
Low levels of coagulation factors in turn may lead to
bleeding disorders.
31. THE END
“Our greatest glory
is not in never
failing but in rising
up every time we
fail.”
Ralph Waldo
Emerson
