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Coagulation Cascade with primary and secondary.pptx

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Abhijith Puttananickal

Haemostasis is the process of stopping bleeding at the site of an injury while maintaining normal blood flow elsewhere. It involves four main steps: vasoconstriction, primary haemostasis (platelet plug formation), secondary haemostasis (clot formation), and fibrinolysis. Secondary haemostasis, also known as the coagulation cascade, involves the intrinsic, extrinsic, and common pathways that activate coagulation factors and ultimately result in a stable fibrin clot. Vitamin K plays an important role by activating coagulation factors II, VII, IX, and X.

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Dr Abhijith J Puttanani 1
Haemostasis is a process that prevents bleeding at the site of an injury while maintaining normal blood flow elsewhere 4 Major Steps Vasoconstriction Primary Haemostasis (platelet plug formation) Secondary Haemostasis (clot formation) Fibrinolysis 2
Vessel's first response to injury Greater the trauma more will be the spasm ,sometimes it can occlude the vessels completely Triggers Direct injury to vascular smooth muscle Secretion of nitric oxide, prostaglandins stop; secretion of endothelin begins further contraction Nervous system reflexes initiated by local pain receptors. Effects Slows down the flow of blood via the vessel Increases the period of contact between platelets and exposed collagen 3
Process by which a platelet plug is formed Steps 1,Exposure Endothelial injury Damage to endothelial cells exposes collagen Damaged cells release Von Willebrand factor which binds to the exposed collagen 4
2,Adhesion GP1B surface proteins on platelets bind to Von Willebrand factor Von Willebrand factor is a large glycoprotein that is present in the plasma and endothelium Once VWF binds to the subendothelium, it exposes multiple binding sites for platelets to adhere, activate, and aggregate. 5
6 3, Activation Platelet changes shape ,first swells then contracts & forms arms to grab other platelets, releases more von Willebrand factor, serotonin, calcium, ADP, thromboxane A2 (positive feedback loop) ADP, thromboxane A2 result in GPIIB/IIIA expression
7 4,Aggregation GPIIB/IIIA binds to fibrinogen, links platelets platelet plug
Clinically Patient can be asymptomatic Skin bleeding Petechiae , Purpura ,Ecchymoses Mucosal Bleeding Epistaxis ,Gingival Bleeding, Menorrhagia, Haemoptysis Investigations Platelet Count Bleeding Time Platelet Aggregometry(Best Method) 8
Aka Secondary Haemostasis. End product - fibrin meshwork. Its called a cascade as from one stage to the next in the Cascade, a greater amount of proenzyme is involved resulting in amplification. Each factor is named in the order of their discovery. Consists of three pathways, the extrinsic, intrinsic, and common pathways, that interact together to form a stable blood clot 9
10 Intrinsic Pathway Extrinsic Pathway Common Pathway Stable Clot
11 Intrinsic Pathway Extrinsic Pathway Common Pathway Stable Clot The extrinsic and intrinsic coagulation pathways both lead into the final common pathway by independently activating factor X. X Xa
12 Thrombin Prothrombin Fibrinogen Fibrin Xa Va Ca++ Membrane Phospholipids STABLE FIBRIN CLOT X X
13 Thrombin Prothrombin Fibrinogen Fibrin Prothrombinase Complex STABLE FIBRIN CLOT
14 Thrombin Prothrombin Fibrinogen Fibrin Xa Va Ca++ Membrane Phospholipids STABLE FIBRIN CLOT
15 Thrombin Prothrombin Fibrinogen Fibrin Xa Va Ca++ Membrane Phospholipids STABLE FIBRIN CLOT X V Thrombin XII I XIII a Ca++ Thrombin
16 Thrombin Prothrombin Fibrinogen Fibrin Xa Va Ca++ Membrane Phospholipids STABLE FIBRIN CLOT X X
17 X Xa
18 X X a Intrinsic pathway begins when factor XII or the Hageman factor is exposed to collagen, kallikrein, and high molecular weight kininogen (HMWK) and is subsequently activated. Factor XIIa activates factor XI into XIa. With a calcium ion, factor XIa activates factor IX Then, factor IXa, factor VIIIa, and calcium form a complex to activate factor X. Factor VIII is found in the blood and is often activated by thrombin (factor IIa). aPTT measures both Intrinsic and Common
19 Thrombin Prothrombin Fibrinogen Fibrin Xa Va Ca++ Membrane Phospholipids STABLE FIBRIN CLOT X X
20 X X a *Tissue factor is aka tissue thromboplastin
21 X Xa The extrinsic pathway begins when there is injury to the surrounding tissues Which exposes tissue factor (factor III) to the blood. Tissue factor then becomes bound with calcium and factor VIIa to activate factor X Factor VII is present in the blood and requires vitamin K to be activated. PT measures both Extrinsic and common pathway
22 Thrombin Prothrombin Fibrinogen Fibrin Xa Va Ca++ Membrane Phospholipids STABLE FIBRIN CLOT X X
23 Vitamin K regulates blood coagulation converts coagulation factors into mature forms Quinone reductase reduces vitamin K quinone (dietary form) into vitamin K hydroquinone Vitamin K hydroquinone donates electrons to y-glutamyl carboxylase, Which Activates the enzyme Adds carboxyl group to glutamic acid residues on proteins This coverts the clotting factors to its active form Vit K dependant Factors are II, VII, IX, X
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Coagulation Cascade with primary and secondary.pptx

Editor's Notes

  • #4: Endothelin isa 21-amino acid long peptide that is a vasoconstrictor produced from endothelial cells, vascular smooth muscle cells (VSMC), macrophages, and the renal medulla.