Vascular Part 1 Flashcards
State five reasons why a thrombus does not normally form in intact vessels.
- Smooth surface
- Prostacyclin
- heparan sulfate
- tissue factor pathway inhibitor (TFPI)
- Thrombomodulin
Platelete activation inhibitor
Prostacyclin
Activates antithrombin
Heparan sulfate
Inactivates VIIa…controls TF/extrinsic pathway
TFPI- Tissue factor pathway inhibitor
Activates protein C pathway
Thrombomodulin
State four procoagulant properties of the vascular intima that lend to thrombus formation during vascular damage.
- Vasoconstriction
- Basement membrane exposes collagen
- von Willebrand factor secreted
- Tissue factor exposed
Necessary for platelets to adhere to subendothelial collagen in arterioles; (and eventual) platelet aggregation.
von Willebrand factor secreted
Activates plasma coagulation system (factor VII)
Tissue factor exposed
Discuss thrombopoiesis:
List the four stages of maturation.
- Megakaryoblast
- promegakaryocyte
- megakaryocyte
- platelets (thrombocytes)
Nucleus round; 2-6 nucleoli; chromatin is homogeneous, loosely organized; cystoplasm basophilic
Megakaryoblast
Nucleus indented; nucleoli are variable; chromatin is condensed and cytoplasm is basophilic
Promegakaryocyte
Nucleus-2-32 lobes (8 lobes are most common); cytoplasm is blue to pink and abundant; granules reddish blue.
Megakaryocyte
No nucleus; light blue to colorless cytoplasm; red to violet, abundant granules.
Platelet (thrombocytes)
Regulatory mechanism of thrombopoiesis.
Growth factor, specifically hormone called thrombopoietin
Sites of platelet production
Medullary=BM; extramedullary=lungs
Describe the morphology of a normal platelet when stained with wright’s stain.
chromomere aka granulomere; Hyalomere
Outside of platelets is light color and round
Name the two pools into which platelets are distributed
Circulatory pool (2/3) and splenic pool (1/3)
state the average life span of the platelet
8-12 days
Discuss four platelet functions.
Source of PF3
Source of PF4
Maintain vessel integrity
formation of platelet plug
Phospholipid found within platelet membrane and is essential reaction site in the cascade.
source of PF 3
Protein found in platelet’s alpha granules and is capable of neutralizing heparin
Source of PF 4
What is the job of maintaining vessel integrity in platelet?
Platelets adhere to the subendothelial collagen, and fill in the gaps until new endothelial cells grow
List four causes of platelet activation caused by traumatic venipuncture and/or shaking of the sodium citrate tube
Subsequent release of PF4
PF4 will neutralize heparin in blood sample
falsely shorten APTT
potential for subsequent over anticoagulation of the paitent
In the formation of the platelet plug: Is it primary or secondary hemostasis?
Primary
In the formation of the platelet plug: does it have short or long term effect?
Short term effect
In the formation of the platelet plug: list two hemostatic systems involved in primary hemostasis?
Vascular intimia and Platelets
In the formation of the platelet plug: List type of bleeding with disorder of Primary hemostasis?
Temporarily arrests bleeding; excessive bruising & mucocutaenouse
In the formation of the platelet plug: type of test are used for diagnostic purposes?
Platelet tests
List the three steps involved in primary hemostasis.
Platelet adhesion
Platelet activation
Platelet aggregation
Discuss the platelet adhesion.
- Platelets first adhere to collagen
- GPIb binds platelet to vWF (bridge)
- GPIb/IX necessary to attach vWF bridge to the subendothelium for platelet adhesion
Discuss the platelet activation.
Platelets release procoagulant factors and synthesize prostaglandins to activate platelets
Discuss the platelet aggregation
Fibrinogen bridge and glycoprotein IIB/IIIa complex needed for platelets to attach to one another that is platelet aggregation
List three zones of platelet ultrastructure.
Peripheral zone
Sol-gel zone
Organelle Zone
Functions as receptor and transmitter region as well as it is essential for adhesion and aggregation.
Peripheral zone
Functions as cytoskeletal/contractile region.
Sol gel zone
Functions as metabolic/organelle region and has two types of granules.
Organelle zone
List two types of granules in organelle zone
Alpha and Dense bodies
Differentiate quantitative vs. qualitative platelet testing.
Quantitative tests– number!!
- Platelet count or slide estimate
Qualitative Tests- Function!!
- Bleeding time, platelet function analyzer (PFA-100), platelet aggregation, clot retraction
Indicate why EDTA is the anticoagulant of choice when performing electronic platelets counts.
It prevents the clumping of platelets
