Haemostasis; Clotting Mechanism (Part 2)

Описание: Hemostasis (Session 2): Coagulation Cascade—Intrinsic & Extrinsic Pathways with Dr. Faiza
Build on Session 1 (vascular constriction and platelet plug) with a clear, step-by-step walkthrough of secondary hemostasis. This lecture explains how thrombin and fibrin are generated, how clots stabilize, the roles of calcium and phospholipids, and why positive feedback rapidly amplifies clot formation.

Personal Stamp: Presented by Dr. Faiza

🔬 Key Topics Covered:
Overview of Clot Formation: From temporary platelet plug to fibrin mesh and clot retraction; fate of clots (lysis vs fibrous organization).
Coagulation Factors: Current nomenclature and sequence of activation; where platelets interface with the cascade.
Common Pathway: Prothrombin activator (Xa + Va + Ca²⁺ + platelet phospholipids) → thrombin → fibrin monomers → fibrin fibers → factor XIII–mediated cross-linking.
Extrinsic Pathway: Tissue trauma → Tissue factor (III) activates VII → X → prothrombin activator formation.
Intrinsic Pathway: Blood/contact activation (collagen, glass) → XII → XI → IX (+ VIII) → X → prothrombin activator.
Timelines & Dynamics: Extrinsic (fast, ~15 s) vs intrinsic (slower, ~1–6 min); positive feedback by thrombin on platelets and factors V, VIII, X.
Essential Cofactors: Critical role of Ca²⁺ (except for factors I and II); how citrate/oxalate chelate Ca²⁺ and act as anticoagulants.
Stabilization & Retraction: Factor XIII cross-linking, platelet cytoskeleton in retraction, and remodeling into fibrous tissue when needed.

🎓 Learning Objectives:
Trace intrinsic and extrinsic pathways to the common pathway and thrombin burst.
Identify the composition and function of the prothrombin activator complex.
Explain thrombin’s dual role in fibrin formation and factor XIII activation.
Differentiate timing and triggers of intrinsic vs extrinsic pathways.
Recognize the importance of calcium and platelet phospholipids in coagulation.

📚 Learning Resources:
Phone: +92 310 7990649
Email: [email protected]

Website: https://www.medicoseacademics.com/

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Dr. Faiza
Assistant Professor of Physiology
MBBS (AIMC, lahore, Best Graduate)
FCPS (Physiology)
CHPE (Certificate in Health Professional Education)
DHPE (Diploma in Health Professional Education)
DHPE (Masters in Health Professional Education)
MBA (Masters of Business Administration)
MPH (Masters of Public Health)
LinkedIn:   / faizaikram  

Tags:
Hemostasis, Coagulation Cascade, Intrinsic Pathway, Extrinsic Pathway, Common Pathway, Prothrombin Activator, Factor Xa, Factor V, Factor XIII, Thrombin, Fibrin, Tissue Factor, Calcium in Coagulation, Platelet Phospholipids, Positive Feedback, Clot Retraction, Fibrous Organization, Anticoagulants, Citrate, Oxalate