Discussing how the coagulation pathways are controlled by inhibitors and fibrinolysis

Home, - Demonstrate your understanding of the haemostatic pathways

Question: - Demonstrate your understanding of the haemostatic pathways by:

a) Discussing how the coagulation pathways are controlled by inhibitors and fibrinolysis

Part a

Coagulation is an active phenomenon and involves homeostasis (refers to as cessation of bleeding). This arrest (thrombohaemmorhagic homeostats) is controlled by the body by complicated relations between coagulation and the fibrinolytic system along with platelets.

General coagulation pathway presents equilibrium between the pro coagulant pathway (which accounts for clot formation) and the mechanisms that inhibit the same further than the injured site. This coagulation process is a cascade of events that leads to hemostasis. The intricate pathway is responsible for fast healing process and prevents the bleeding.

The coagulation process is monitored and maintained by various inhibitors, which stops the clot formation, by preventing the formation of thrombus.

Disparity in the coagulation system can happens in the perioperative period, which can results in factors such as thrombosis or bleeding.

Coagulation pathway includes primary hemostasis which accumulate the platelets and secondary hemostasis as well, which includes two pathways, extrinsic as well as intrinsic, are originately separate but merged at a level, and leads to formation of fibrin activation.  Its overall aim is to stabilize the plug of platelet with a fibrin mesh. The commonest pathways activates the fibrinogen into the fibrin. The hemostasis can be done by several clotting factors. The intrinsic pathway consists of factors I (fibrinogen), II (prothrombin), IX (Christmas factor), X (Stuart-Prower factor), XI (plasma thromboplastin) , and XII (Hageman factor). The extrinsic pathway consists of factors I, II, VII (stable factor), and X. Lastly, the common pathway consists of factors I, II, V, VIII, X.

Fibrin is significant for hemostasis as both the primary product of the coagulation cascade and the final substrate for fibrinolysis.

Fibrinolysis competence is very much influenced by clot structure, Regulation of the fibrinolytic system, like that of the coagulation cascade, is accomplished by varous cofactors, receptors, and inhibitors.


b. providing the possible reasons for the patient's results shown in Table 2.

Test          Result                  Reference range       Units

PT/INR    1.9                          0.8-1.2                      N/A

APTT/APR  2.0                    0.8 - 1.2                     N/A

Fibrinogen level 3.0              1.8- 4.5                        g/l

Part B

Increased PT/INR means blood is taking long time to clot. Increased APTT means patient might have a bleeding disorder. 

It may be due to disturbed and defective intrinsic pathways and deficiency of clotting factors. 

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