Hemostasis and Clotting

Thrombopoietin

Released by the liver; stimulates bone marrow and protects platelets.

Platelets

Cell fragments made in bone marrow; initiate clotting.

TXA2

Released from injured endothelial cells; activates platelets and stimulates aggregation.

Von Willebrand factor (vWf)

adhesive protein for platelets, sourced from endothelial cells.

Factor X

Converts prothrombin to thrombin in the coagulation cascade.

Thrombin

Converts fibrinogen to fibrin during coagulation.

Fibrin

Forms a thread-like mesh to hold platelets together in a clot.

Plasmin

Enzyme that breaks down fibrin, leading to clot dissolution.

Normal Hemostasis

The process that stops blood loss effectively.

Abnormal Hemostasis

Occurs when clotting happens inappropriately or fails to occur.

Role of Endothelium in Hemostasis

Inhibits coagulation through the release of prostaglandins, nitric oxide, and vWF.

Vasoconstriction stage of Hemostasis

Smooth muscle contracts to reduce blood loss.

Formation of a Platelet Plug stage

Aggregation of platelets attracted to damaged vessel walls by collagen.

Blood Coagulation stage

Activation of Factor X initiates the fibrin cascade for clot formation.

Fibrinolysis stage

Thrombin converts plasminogen to plasmin which dissolves fibrin threads.

Intrinsic Pathway of Coagulation

Slower response activated by damaged blood vessels.

Extrinsic Pathway of Coagulation

Faster response activated by damaged tissue.

Warfarin and Heparin

Anticoagulant that decreases thrombin production.

Acetylsalicylic acid (Aspirin)

Inhibits platelet aggregation, preventing clot formation.

Thrombolytics and Tissue Plasminogen Activators

Medications that increase plasminogen to promote clot breakdown.

Thrombocytopenia

Condition characterized by decreased platelet levels.

Etiology of Thrombocytopenia

Caused by bone marrow suppression.

Manifestations of Thrombocytopenia

Results in easy bleeding and impaired clotting.

Von Willebrand Disease

Hereditary disorder affecting platelet function due to vWf deficiency.

Manifestations of Von Willebrand Disease

Includes skin rashes, frequent nosebleeds, easy bruising, gum bleeding.

Prolonged ASA Use Complications

Can result in excessive bleeding due to impaired clotting.

Deep Vein Thrombosis (DVT)

Formation of blood clots in deep veins, primarily of the legs.

Complications of Deep Vein Thrombosis (DVT)

Potential for thromboembolism, leading to pulmonary embolism.

Hypercoagulable state

A condition that increases the risk of clot formation.