Coagulation Profile
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Lab# 8
BCH 220
Coagulation Profile
Objectives:
1
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.
Coagulation
is a complex process by which blood forms clots.
It is an important part of
hemostasis
(the cessation of blood loss from a damaged vessel).
Disorders of coagulation can lead to an increased risk of bleeding (hemorrhage) or
clotting (thrombosis).
Coagulation:
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:
1-
Vascular spasm
, Damaged blood vessels
constrict.
2-
Platelet plug formation,
Platelets adhere
to damaged endothelium to form platelet
plug (
primary hemostasis
)
3-
Blood Coagulation,
Clots form upon the
conversion of fibrinogen to Fibrin (
secondary
hemostasis
).
Clotting
Cascade
•
A
cascade
is
a
mechanism in which enzymes activate other
enzymes sequentially usually leading to an amplification of an
initial signal.
•
Pathways
•
Extrinsic
•
Intrinsic
•
Each
of
these
pathways leads to the conversion of factor X
(inactive) to factor Xa (active)
Initially independent, then they converge on
common pathway leading to the formation of a
fibrin clot
What triggers extrinsic and intrinsic pathways:
Extrinsic—Release of biochemicals from broken blood vessels/damaged tissue.
Intrinsic—No tissue damage, blood contacts damaged endothelial layer of blood
vessel walls.
Simple test but takes time and rarely done now.
Method:
Venous blood is taken and placed on glass test tube at 37°C and it
observed at time intervals until clotting occurs
Normal blood takes 5-10min to clot
Longer periods
Coagulation defects (e.g. Hemophilia)
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Clotting time - capillary method
BLEEDING TIME
Provides assessment of
platelet count
and function
Method:
It is determined by noting time at which blood coming out a small cut, no longer forms a
spot on a piece of filter paper placed in contact with cut surface.
The normal range from 2-4 min
PROTHROMBIN TIME (PT)
Method:
An excess of tissue factor and Ca2+ ions are added to diluted plasma
containing citrate (anticoagulant) and then the time taken for the mixture
to clot is measured
Normal value
Normal value
10-15 secs
10-15 secs
High PT
low levels of thrombin.
Results from liver disease due to deficiency of prothrombin, fibrinogen, V, VII
and X factors
Vital process in hemostasis, crucial for blood clot formation. Discover the mechanisms behind coagulation, including intrinsic and extrinsic pathways. Learn about clotting cascade, clotting time estimation, and the role of vascular spasm, platelet plug formation, and blood coagulation in maintaining hemostasis.
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Presentation Transcript
Lab# 8 BCH 220 Coagulation Profile
Objectives: 1-To estimate Clotting time, Bleeding time, and Prothrombin time .
Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis (the cessation of blood loss from a damaged vessel). Disorders of coagulation can lead to an increased risk of bleeding (hemorrhage) or clotting (thrombosis).
Hemostasis is maintained in the body via three mechanisms 1- Vascular spasm, Damaged blood vessels constrict. 2- Platelet plug formation, Platelets adhere to damaged endothelium to form platelet plug (primary hemostasis) 3- Blood Coagulation, Clots form upon the conversion of fibrinogen to Fibrin (secondary hemostasis).
Clotting Cascade A cascade is a mechanism in which enzymes activate other enzymes sequentially usually leading to an amplification of an initial signal. Pathways Initially independent, then they converge on common pathway leading to the formation of a fibrin clot Extrinsic Intrinsic Each of these pathways leads to the conversion of factor X (inactive) to factor Xa (active)
What triggers extrinsic and intrinsic pathways: Extrinsic Release of biochemicals from broken blood vessels/damaged tissue. Intrinsic No tissue damage, blood contacts damaged endothelial layer of blood vessel walls.
Clotting time Simple test but takes time and rarely done now. Method: Venous blood is taken and placed on glass test tube at 37 C and it observed at time intervals until clotting occurs Normal blood takes 5-10min to clot Longer periods Coagulation defects (e.g. Hemophilia)
BLEEDING TIME Provides assessment of platelet count and function Method: It is determined by noting time at which blood coming out a small cut, no longer forms a spot on a piece of filter paper placed in contact with cut surface. The normal range from 2-4 min
PROTHROMBIN TIME (PT) Method: An excess of tissue factor and Ca2+ ions are added to diluted plasma containing citrate (anticoagulant) and then the time taken for the mixture to clot is measured Normal value 10-15 secs High PT low levels of thrombin. Results from liver disease due to deficiency of prothrombin, fibrinogen, V, VII and X factors
