PRIMARY

• Vascular defects that lead to increased permeability and increased vascular fragility

  Hemorrhagic disease (non-thrombogenic purpura)
• Causes of increased permeability


  • Vitamin C deficiency (scurvy)
  • Purpura senilis
• Causes of increased vascular fragility

  • Old age
  • After cortisone administration
  • During menopause
  • In the course of infection
  • In the course of endocrine disturbances (Cushing's)
  • Toxemias (diabetes and uremia)
  • Variety of drugs (e.g, barbiturates, salicylates, etc.)
• Other forms of vascular disorders

  • Henoch-Schoenlein purpura
  • Purpura fulminans
  • Hereditary hemorrhagic telangiectasia
  • Waterhouse-Friedrichsen syndrome
• Laboratory findings in vascular defects

  • Bleeding time-prolonged
  • Tourniquet test-positive
  • Coagulation time, clot retraction, platelet count, PT, PCT, PTT - normal
• 14-18 um, round nucleus with homogenous chromatin, NC Ratio of 3:1, earliest recognizable stage

  Megakaryoblast (MK-I)
• 15-40 um, indented nucleus with moderately condensed chromatin, N:C Ratio of 1:2

  Promegakaryocyte (MK-II)
• 30-50 um, multilobed nucleus with deeply and variably condensed chromatin, N:C Ratio of 1:4, Largest cell in BM

  Megakaryocyte (MK-III)
• Areas within the platelet

  • Peripheral zone
  • Sol-gel zone/structural zone
  • Organelle zone
  • Submembrane area
• Specific functions of the peripheral zone

  • Responsible for platelet adhesion and aggregation
  • Contains glycocalyx with glycoproteins
• Glycoproteins in the peripheral zone: provide its function

  • Glycoprotein Ib/IX/V -
  • Glycoprotein IIb/IIIa -
  • Glycoprotein V -
  • GP VI -
  • Glycoprotein Ib/IX/V - receptor protein for binding of vWF
  • Glycoprotein IIb/IIIa - binding site for Fibrinogen
  • Glycoprotein V - Thrombin substrate
  • GP VI- collagen key receptor
• Bernard-Soulier Syndrome

  Absence of GP lb/tx/v
• Glanzmann's Thrombasthenia

  Absence of GP IIb/IIla
• Provides support for cell structure and mechanism for cell contraction, consists of thrombasthenin, microfilaments and microtubules

  Sol-gel zone/structural zone
• Components of the organelle zone

  • Mitochondria
  • Lysosomes
  • Alpha Granules
  • Dense Granules
• Contents of alpha granules

  • PDGF
  • Fibronectin
  • Fibrinogen
  • Thrombospondin
  • PLATELET factor 4
  • Beta – thromboglobulin
  • vWF
  • vWF plasminogen
• Contents of dense granules

  • Calcium ADP
  • Serotonin
  • Pyrophosphate
  • ATP
• Links the inner cell body to the membrane

  Submembrane area
• Arachidonic acid metabolism, also serves as the control center of activation

  Dense tubular system
• It Release of granules

  Open canalicular system
• Stages of platelet activation:

  • Adhesion
  • Aggregation
  • Secretion
  • Clot retraction
• Responsible for clot retraction

  Thrombasthenin
• Red, pinpoint hemorrhagic spots; caused by capillary inability to withstand normal trauma

  Petechiae
• Hemorrhage of blood into small areas of the skin, mucous membranes and other tissues

  Purpura
• Form of purpura in which blood escapes into large areas of the skin or mucous membranes

  Ecchymosis
• Types of bleeding

  • Epistaxis -Nosebleed
  • Hematochezia - Fresh blood in stool (red)
  • Melena - Old blood in stool (black)
  • Hemarthrosis - Leakage of blood into the joint cavity
  • Hematemesis - Vomiting of blood
  • Hemoptysis – expectoration of blood
  • Hematohidrosis - Sweating of blood
  • Menorrhagia - Excessive menstrual bleeding
• Platelet aggregates reinforced by fibrin

  Thrombus