Hematologic System Disorders

What are the main components of the hematologic system?

Blood vessel wall, white blood cells, red blood cells, platelets, and blood plasma.

What are the five stages of hemostasis?

1. Vessel spasm (vasoconstriction)
2. Platelet plug formation (activation, adhesion, aggregation)
3. Blood coagulation (fibrin clot)
4. Clot retraction (edges of vessel join)
5. Clot dissolution (fibrinolysis)

What are the two main categories of hemostasis disorders?

1. Thrombosis – inappropriate clot formation
2. Bleeding – failure to clot appropriately

What three components are required for clotting?

1. Platelets (from bone marrow)
2. Von Willebrand Factor (adhesion & carrier protein)
3. Clotting factors (made in liver using vitamin K)

Why is hemostasis necessary?

Maintains vascular integrity and prevents loss of volume, oxygen, and promotes healing after infection or tissue damage.

What role does Antithrombin III play in coagulation?

Inactivates coagulation factors; when paired with heparin, it prevents uncontrolled thrombus formation.

What is the function of Protein C and Protein S?

Protein C inactivates factors V and VIII; Protein S accelerates Protein C.

What is plasmin’s function?

Breaks down fibrin → fibrin degradation products (act as anticoagulants)

What is hypercoagulability?

An increased risk of forming clots (arterial or venous).

What causes arterial vs. venous thrombi?

• Arterial: Turbulent flow + platelet adhesion
• Venous: Blood stasis + high clotting factors

What leads to increased platelet function?

• Flow disturbances
• Endothelial damage
• Platelet hypersensitivity

What general conditions increase platelet function?

Atherosclerosis, diabetes, smoking, high lipids/cholesterol, high platelet count

What conditions cause increased coagulation activity?

Pregnancy, contraceptives, post-surgery, immobility, CHF, cancer

How does atherosclerosis relate to clotting?

Vessel damage → platelet adhesion → growth factor release → smooth muscle proliferation → plaque buildup

What is thrombocytopenia?

Low platelet count due to:
• ↓ production
• ↑ sequestration (spleen)
• ↓ survival

Types of thrombocytopenia?

• Drug-induced
• Idiopathic thrombocytopenic purpura (ITP)
• Thrombotic thrombocytopenic purpura (TTP)

What causes bleeding related to platelets?

• Low platelet count (severe)
• Impaired platelet function
• Bleeding common in small vessels: petechiae, purpura

Where does bleeding commonly occur in thrombocytopenia?

Mucous membranes (nose, mouth, GI, uterus)

What are petechiae and purpura?

• Petechiae: Tiny red-purple spots (platelet issue)
• Purpura: Larger purple bruises

What is a thromboembolic disease?

Fixed (thrombus) or moving (embolus) clot that obstructs vessels → tissue ischemia or death (heart, brain, lungs)

Arterial vs. Venous thrombi causes?

• Arterial: Protein defects in hemostasis
• Venous: Clinical disorders (immobility, surgery, cancer)

How is thromboembolic disease treated?

• Anticoagulants: Heparin, Warfarin
• Thrombolytics: Streptokinase, Urokinase

What is Virchow’s Triad?

1. Vessel injury (e.g., atherosclerosis)
2. Blood flow abnormalities
3. Hypercoagulability

What is the difference between primary and secondary thrombophilia?

• Primary: Inherited protein defects (e.g., Protein C/S deficiency)
• Secondary: Acquired (e.g., prolonged immobility, cancer)

What is vitamin K’s role in coagulation?

• Essential for clotting factor synthesis
• Fat-soluble, made by gut bacteria
• Deficiency → inactive factors → abnormal bleeding

What causes coagulation factor deficiencies?

• Defective synthesis
• Genetic disorders (Hemophilia A, B, Von Willebrand)
• Increased consumption (e.g., DIC)

What is antiphospholipid syndrome?

Autoimmune disorder with antibodies against membrane phospholipids → ↑ clot risk
Tx: Heparin + aspirin

How are hereditary thrombophilias inherited?

Most are autosomal dominant (e.g., Factor V Leiden)

What are examples of vascular disorders that cause bleeding?

• Hereditary hemorrhagic telangiectasia (thin-walled capillaries)
• Scurvy (vitamin C deficiency → poor collagen)
• Cushing disease (protein wasting from cortisol)
• Senile purpura (aging)

What is DIC?

A disorder where clotting and bleeding happen simultaneously due to widespread coagulation activation.