BIO230 Chapter 11 Extended

Hemostasis

The regulated process that stops bleeding, stabilizes the injury, and removes the clot once healing occurs.

Vascular Component

The first stage after injury involving immediate vasoconstriction and exposure of collagen and tissue factor.

Collagen exposure

The trigger for platelet activation and the intrinsic coagulation pathway.

Scurvy

A vitamin C deficiency that leads to weak collagen and fragile blood vessels.

Ehlers-Danlos syndrome

A connective tissue defect that causes bleeding even if platelets and coagulation factors are normal.

Platelet Component

The stage of hemostasis where platelets form the initial plug, also known as primary hemostasis.

Megakaryocytes

The cells in the bone marrow responsible for the production of platelets.

Platelet plug formation

The process whereby platelets adhere to the damaged vessel, aggregate, and provide a surface for coagulation factors.

vWF

Von Willebrand factor, which binds collagen and helps platelets adhere to the damaged vessel.

GpIb

A receptor on platelets that helps them bind to von Willebrand factor.

GpIIb/IIIa receptors

Receptors on platelets that bind fibrinogen for aggregation.

Primary platelet plug

The temporary and unstable aggregate of platelets that initially forms at the site of vessel injury.

Coagulation Component

The stage of hemostasis that stabilizes the platelet plug with fibrin, also known as secondary hemostasis.

Activated factors

Coagulation factors that have an 'a' designation indicating they are active (e.g., Xa, VIIa).

Calcium (Ca²⁺)

A necessary component for the coagulation process.

Platelet phospholipid (PF3)

A component required for the coagulation process.

Extrinsic Pathway

The coagulation pathway triggered by tissue factor, associated with factor VII and tested by PT/INR.

Warfarin

A medication that affects the extrinsic pathway of coagulation.

Intrinsic Pathway

The coagulation pathway triggered by collagen contact, involving factors XII, XI, IX, and VIII, and tested by aPTT.

Heparin

A medication that affects the intrinsic pathway of coagulation.

Common Pathway

The coagulation pathway that begins at Factor X and leads to the formation of thrombin from prothrombin.

Thrombin

An enzyme that converts fibrinogen to fibrin, facilitating the formation of a stable blood clot.

Factor XIII

A coagulation factor that cross-links fibrin to stabilize the clot.

Fibrinolysis

The controlled removal of a clot once healing occurs, involving the breakdown of fibrin.

Plasmin

An enzyme responsible for breaking down fibrin during fibrinolysis.

Fibrin degradation products (D-dimer)

Substances produced from the breakdown of fibrin, elevated in various clinical conditions.

Thrombocytopenia

A quantitative platelet disorder characterized by a decreased platelet count.

Petechiae

Small purple or red spots on the skin caused by bleeding.

Purpura

Larger purple spots on the skin due to bleeding underneath.

Ecchymosis

A larger bruise that results from bleeding under the skin.

Mucosal bleeding

Bleeding that occurs in mucosal tissues, often associated with platelet disorders.

Aspirin

A medication that can cause qualitative platelet disorders by inhibiting platelet function.

Uremia

A condition resulting from kidney failure that can affect platelet function.

Liver disease

A condition that can lead to qualitative disorders in platelet function.

von Willebrand Disease

A disorder characterized by defective platelet adhesion and decreased factor VIII stability.

Hemophilia A

A genetic disorder caused by a deficiency of factor VIII, leading to bleeding issues.

X-linked recessive

The pattern of inheritance for hemophilia A, predominantly affecting males.

↑ aPTT

An indicator of a clotting issue associated with hemophilia A.

Hemarthrosis

Bleeding into a joint, commonly seen in hemophilia.

Mixing Studies

Tests used to determine the presence of inhibitors in coagulation by mixing patient plasma with normal plasma.

Corrects

Indicates a factor deficiency when mixing studies show improvement in PT/aPTT.

Does not correct

Indicates the presence of an inhibitor when mixing studies do not improve PT/aPTT.

Petechiae + normal PT/aPTT

A pattern indicating a platelet disorder.

↑ aPTT only

A pattern indicating an intrinsic pathway defect.

↑ PT only

A pattern indicating an extrinsic pathway defect.

Normal platelets + joint bleeding

A pattern indicative of hemophilia.

Elevated D-dimer

An indicator of active clot breakdown.

Balance in hemostasis

The equilibrium that prevents excessive bleeding or thrombosis.

Vasoconstriction

The immediate response of blood vessels to injury that reduces blood flow.

Tissue factor

A key trigger for the extrinsic coagulation pathway.

Prothrombin

The precursor to thrombin in the coagulation cascade.

Fibrinogen (I)

The soluble plasma protein that is converted to fibrin by thrombin.

Temporary and unstable plug

Characteristic of the primary hemostasis until stabilized by fibrin.

Clinical significance of D-dimer

Elevated levels may indicate conditions like DVT, PE, MI, and stroke.

Sequestration/dilution

A condition that may lead to thrombocytopenia due to pooling of platelets.

Prolonged bleeding time

A characteristic of qualitative platelet disorders.

Deep bleeding

A bleeding pattern characteristic of hemophilia, especially into muscles and joints.

Severity of hemophilia A

Based on factor activity levels; severe, moderate, or mild.

Defective platelet adhesion in von Willebrand Disease

Results from impaired function of von Willebrand factor.

Coagulation disorder symptoms

Include deep bruising, internal bleeding, and prolonged bleeding times.

Screening Tests

Initial assessments used to evaluate hemostatic function.

Clinical links for collagen disorders

Scurvy and Ehlers-Danlos syndrome demonstrate the importance of collagen in hemostasis.

Role of calcium in coagulation

Essential for several steps in the coagulation cascade.

Fibrin stabilization

The role of secondary hemostasis in forming a stable clot.

Influence of medications on coagulation pathways

Warfarin and heparin target different pathways affecting hemostasis.

Signs of thrombocytopenia

Can include spontaneous bruising and prolonged bleeding after minor injuries.

Interpreting abnormal PT or aPTT

Essential for diagnosing potential coagulation factor deficiencies or inhibitors.

Importance of balancing hemostasis

Too little activity can cause bleeding; too much can lead to thrombosis.

Management of clotting disorders

Involves addressing the underlying cause, such as factor replacement or medication.

Role of platelets in primary hemostasis

Adhesion, aggregation, and providing surfaces for clotting factors.

Definition of hemostasis balance

Preventing excessive bleeding while avoiding unwanted clot formation.

Symptoms of qualitative platelet disorders

Prolonged bleeding time without a decrease in platelet count.