HCP 3 Flashcards
What are the progenitor cells to platelets?
Giant Megakaryocytes
How long do platelets last in circulation?
7-10 days
List the different platelet binding proteins that platelets have and what they bind to
- GpIc/IIa: laminin and fibronectin
- GpIb: vWF
- GpIa/IIa: collagen exposed on subendothelium
Contents of alpha granule?
Factor V, Fibronectin, vWF, Fibrinogen, PDGF, PF4, TGF
Contents of delta (dense) granule?
Serotonin, ADP, ATP, Ca2+, Epinephrine
Where is vWF made and where is it found?
Made by endothelial cells and megakaryocytes
Found in Weibel-Palade bodies, circulation, and alpha granules
What do endothelial cells express to prevent platelet activation/aggregation?
PGI2 (prostacyclin), Nitric oxide, ADPase
What 2 events are referred to as “platelet activation”?
- Shape change of platelet from discoid to spikey
- Degranulation
Alternate name for Factor XII?
Hageman Factor
Alternate name for Factor IX?
Christmas Factor
Alternate name for Factor X?
Stuart Factor
What factor is Tissue Factor?
Factor III
What Factor is Prothrombin?
Factor II
What Factor is Fibrinogen?
Factor I
What Factor is Ca2+
Factor IV
How does the extrinsic pathway get quickly inactivated?
After production of a small amount of Xa, TFPI inhibits the TF-VIIa-Ca2+ complex
What is a blood clot?
Mass composed platelets & fibrin, with erythrocytes leukocytes, and serum entrapped in fibrin
What is a thrombus?
Intravascular blood clot (cannot be used interchangeably with “blood clot”)
What are the anticoagulant factors?
Tissue Factor Pathway Inhibitor (TFPI)
Antithrombin III
Thrombomodulin
Protein C (With Protein S as a cofactor)
What is the half-life of free Factor VIII and VIII-vWF?
Free factor VIII: 2.4 hours
VIII-vWF: 12 hours
Describe Hemophilia A
- Mutation in Factor VIII gene
- X linked Recessive Trait (affects males and homozygous females)
- Prolonged PTT
- Normal PT and bleeding time
Describe Hemophilia B
- Mutation if Factor IX gene
- X linked Recessive Trait (affects males and homozygous females)
- Prolonged PTT
- Normal PT and bleeding time
Where is the Factor VIII gene located?
Where is the Factor IX gene located?
VIII: Tip of long arm of X chromosome Xq28
IX: Tip of long arm of X chromosome Xq27.1
What is bleeding time?
Test done to asses platelet function; measure time from start of bleeding to platelet plug formation
What does the Partial Thromboplastin Time Assay test for?
Intrinsic Pathway function
XII, XI, IX, X, V, II, I
What does the Prothrombin Time assay test for?
Extrinsic Pathway function
VII, X, V, II, I
What are the 3 main abnormalities that are part of thrombus formation?
- Endothelial Injury
- Stasis or Turbulent blood flow
- Hypercoagulability
What are 4 things that can happen to a thrombus?
- Propagation
- Embolization
- Dissolution
- Organization/Recanalization
Where is a DVT most likely to occur?
In the deep veins at or above the knee
-Femoral, popliteal, iliac veins
What is the most important activator of Factor X?
Tenase
Type I vWD?
- Autosomal dominant; 70% of all cases
- Incomplete penetrance; variable expressivity
- Decreased maturation of increased clearance from plasma
Type 2A vWD?
Decreased formation vWF multimers
Type 2B vWD?
defective vWF has enhanced binding to GpIb (spontaneous binding);–>increased clearance
Type 2M vWD?
Decreased binding capacity to GpIb
Type 2N (Normandy) vWD?
Decreased binding capacity to factor VIII; mutation in Factor VIII binding domain
What are the 5 sources of arterial supply for medial and lateral nasal cavity walls?
- Anterior ethmoidal artery
- Posterior Ethmoidal artery
- Sphenopalatine Artery
- Greater palatine artery
- Septal bran of superior labial artery
Where do the 5 arteries anastomose?
Keisselbach area (highly vascular)
What factor and proteins use Vitamin K as a cofactor?
Factors: II, VII, IX, X
Proteins: C &S
What is the name of vitamin K1 and what are its sources?
Phylloquinone
Leafy green vegetables (cabbage, kale, spinach)
What is the name of vitamin K2 and what are its sources?
Menaquinone
Eggs, liver, fermented food, gut bacterial
Where does our major source of vitamin K come from?
K2; Gut bacteria
What form of vitamin K is used as a cofactor?
What enzyme is vitamin K a cofactor for?
- Dihydroquinone/Hydroquinone vitamin K
- gamma-glutamyl carboxylase
What enzyme reduces epoxide vitamin K to quinone vitamin K?
Vitamin K epoxide reductase (enzyme action is inhibited by warfarin)
Why heparin before warfarin?
- Heparin is taken first to decrease thrombin levels
- Warfarin has to be administered second because it initially stimulates coagulation by fast inhibition of protein C & S
What is a saddle embolus?
Embolism in main pulmonary artery bifurcation (will cause instant death)
Why are extended bed rest and immobilization considered risk factors for DVT?
There is reduced milking action of the veins by the leg muscles, which causes stasis/pooling/decreased washout of factors and decreased venous return
What does thrombin do?
activates factors V, VIII, IX, XI, XIII
Activates protein C
binds to PAR-1 on platelet ➡️ increase platelet activation
converts fibrinogen to fibrin
