PPOM 1 Week 18 LEC 164: The Coagulation Cascade

Source: https://www.youtube.com/watch?v=dl6uMKJRJmQ Don't use the Khan Academy Video Dr. Goldstein recommends, it's not as intuitive

Factor I

AKA Fibrinogen, precursor for Fibrin protein which becomes weak strands, then Fibrin mesh. “Common Pathway”

Factor Ia

AKA Fibrin, protein that forms polymers to strengthen platelet clot formed during Primary Hemostasis. “Common Pathway”

Factor XIIIa

AKA Fibrin Stabilization Factor, strengthens Fibrin strands into Fibrin mesh through crosslinking. “Common Pathway”

Factor XIII

AKA unactivated form of Fibrin Stabilization Factor, must be activated by Thrombin before it can crosslink Fibrin strands together. “Common Pathway”

Factor III

AKA Tissue Factor or Tissue Thromboplasin, expressed by damaged tissue outside blood vessels to initiate Extrinsic Pathway. Converts Factor VII to Factor VIIa (along with Thrombin)

Factor IIa

AKA Thrombin, protein that combines with Ca²⁺ to convert Fibrinogen to Fibrin. Also activates Fibrin Stabilization Factor to crosslink Fibrin strands, as well as Factor VII so that it can get Common Pathway started with Factor Xa, AND Factor V to Va. “Common Pathway”

Factor II

AKA Prothrombin, inactive factor that is converted to Thrombin by Prothrombin Activator Complex. “Common Pathway”

Factor Xa

1 of 2 parts of Prothrombin Activator Complex which combine with Ca2+ in order to convert Prothrombin to Thrombin, which ultimately converts Fibrinogen to Fibrin. Starts the “Common Pathway”

Factor Va

1 of 2 parts of Prothrombin Activator Complex which combine with Ca2+ in order to convert Prothrombin to Thrombin, which ultimately converts Fibrinogen to Fibrin. Starts the “Common Pathway”

Factor IV

AKA Ionized Calcium (CA²⁺), used to change many of the factors (proteins) from their standard to activated forms. Involved in multiple pathways

Extrinsic Pathway

AKA “Tissue Factor Pathway”, initiated by damage to tissue and vasculature, allowing blood to come into contact with tissue.

Common Pathway

Pathway that is initiated by Prothrombin Activator Complex in order to convert Prothrombin to Thrombin (which itself will later convert Fibrinogen to Fibrin)

Intrinsic Pathway

AKA “Contact Activation Pathway”, triggered by inflammation/damage to blood cells or endothelial cells; result of blood being exposed to collagen of subendothelial layer. Lot more steps involved in cascade and slower, secondary response but produces larger amount of fibrin. Amplification phase

Factor VII

Factor that is activated by Tissue Factor in the Extrinsic Pathway, as well as Thrombin; its activated form is later activated by Ca²⁺ as well. Large amount in blood, starting point for initiation of Cascade. Involved in multiple pathways

Factor VIIa

Factor that is activated by Ca²⁺ to convert Factor X to Factor Xa, which starts the Common Pathway. “Extrinsic Pathway”

Factor XII

First factor that will be activated when the Intrinsic pathway is initiated. “Intrinsic Pathway”

Factor XIIa

Factor that combines with various cofactors to convert Factor XI to Factor XIa. “Intrinsic Pathway”

Factor XIa

Factor that combines with Ca²⁺ to convert Factor IX to Factor IXa. “Intrinsic Pathway”

Factor IXa

Factor that converts Factor VIII to Factor VIIIa; also combines with Factor VIIIa, platelet phospholipids, and Ca²⁺ ions to form a complex that activates Factor X to start off the Common Pathway. “Intrinsic Pathway”

Factor VIII

Factor that is activated by Factor IXa in the Intrinsic Pathway to form complex with Factor IXa as well as platelet phospholipids and Ca²⁺

Prothrombin Time (PT)

Coagulation study that measures Extrinsic Pathway

Activated Partial Thromboplastin Time (aPPT)

Coagulation study that measures Intrinsic Pathway