Platelet Differentiation and Hemostasis

These flashcards cover vocabulary related to platelet differentiation, hemostasis, and common bleeding and clotting disorders.

Platelet Differentiation

The process when myeloid stem cells become megakaryocytes and fragment into platelets.

Thrombopoiesis

The process of platelet production regulated by thrombopoietin.

Megakaryocytes

Large cells in the bone marrow that fragment to form platelets.

Thrombopoietin (TPO)

A hormone that regulates platelet production.

Primary Hemostasis

Formation of a platelet plug in response to vascular injury. (adhesion, activation, aggregation)

Platelet Aggregation

Plts have receptors that bind to fibrogen that acts as a bridge to bind to other plts

Fibrinolysis

The breakdown of clots, important for preventing excessive clotting.

Coagulation Cascade

clotting factors float in blood in inactive form (XII) and wait for injury (vascular or tissue) to convert fibrinogen to fibrin

Intrinsic Pathway

Clotting pathway activated by collagen in the case of vascular injury. Hagman factor activated XIIa → Xa

Extrinsic Pathway

Clotting pathway activated by tissue factor release from damaged tissues. Tissue factor directly activates Xa

Common Pathway

Pathway where intrinsic and extrinsic converge to produce thrombin (IIa). needs Ca and prothrombinase complex to convert prothrombin into thrombin.

Thrombin

An enzyme that converts fibrinogen into fibrin during coagulation, amplifies cascade, activates monocytes, promotes adhesion molecules expression and interaction with leukocytes for inflammation

von Willebrand Factor (vWF)

A protein that facilitates platelet adhesion to blood vessel walls.

Calcium in Coagulation

Essential cofactor for activation of several clotting factors.

Antithrombin III (AT-III)

A protein that inhibits thrombin and other clotting factors.

Protein C

A protein that helps downregulate clotting by degrading Factors Va and VIIIa.

Thrombocytopenia

A condition characterized by abnormally low platelet counts. (bleeding risk)

Thrombocytosis

A condition characterized by abnormally high platelet counts. (clotting risk)

Hemophilia A

A genetic disorder caused by deficiency of Factor VIII.

Hemophilia B

A genetic disorder caused by deficiency of Factor IX.

Factor V Leiden

A mutation that makes Factor V resistant to inactivation by Protein C.

Vitamin K

A vitamin necessary for the synthesis of clotting factors II, VII, IX, and X.

Partial Thromboplastin Time (PTT)

A blood test measuring the intrinsic pathway of coagulation.

Prothrombin Time (PT)

A blood test measuring the extrinsic pathway of coagulation.

Adenosine diphosphate (ADP)

A molecule released from platelets that promotes activation and aggregation.

Clot contraction

Process that stabilizes the clot by reducing its size.

Serotonin (5-HT)

A compound released by platelets that causes vasoconstriction.

Thromboxane A₂ (TxA₂)

A potent vasoconstrictor produced by activated platelets.

Spleen in Hemostasis

Organ that can sequester platelets, affecting blood counts.

Liver Disease Impact

Impaired production of clotting factors leading to increased bleeding risk.

Mucocutaneous bleeding

Bleeding from the mucous membranes, commonly seen in certain disorders.

Deep vein thrombosis (DVT)

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

Pulmonary embolism (PE)

A blockage in the pulmonary arteries caused by blood clots.

Nutritional deficiencies

Lack of vitamins necessary for proper blood coagulation.

Glycoprotein Ib-IX-V complex

A receptor complex on platelets that facilitates adhesion to collagen.

Stable fibrin clot

A clot that results from the conversion of fibrinogen to fibrin.

Endothelial cells

Cells lining blood vessels that play a critical role in hemostasis.

CBC (Complete Blood Count)

A blood test used to assess overall health and detect disorders.

Endomitosis

A process where cells undergo replication without division, yielding polyploid cells.