Hemostasis & Coagulation

Question 1

Platelet developement

Answer 1

Stem Cell
Megakaryoblast
Megakaryocyte
Megakaryocyte Break-up
Platelets

Question 2

Platelet parts:

Answer 2

Glycoprotein Coating: prevents plts from adhearing to normal vasculature
Contractile Proteins: actin, myosin, and thrombosthenin
ER and Golgi Apparatus: Ca++ and enzyme storage
Mitochondria: ADP and ATP synthesis
PG and TXA2 synthesis
Fibrin stabilizing factor synthesis
Growth factors

Question 3

Stages of Hemostasis

Answer 3

1. vascular constriction
2. platelet plug is formed
3. blood coagulation/clot formed
4. fibrin formation and repair of injured vessel
5. clot lysis

Question 4

Von Willebrand Factor

Answer 4

• produced by capillary endothelial cells

- attracts platelets to tear in blood vessel wall

Question 5

Steps of Coagulation

Answer 5

1. activation of coagulation factors and formation of PROTHROMBINASE (prothrombin activator)
2. Prothrombinase converts PROTHROMBIN to THROMBIN
3. Thrombin converts FIBRINOGEN to FIBRIN FIBERS

fibrin fibers = enmeshed platelets, blood cells, and plasma to form clot

Question 6

Final outcome of Stage 1 of the clotting pathway?

Answer 6

Prothrombinase

Question 7

Extrinsic Clotting Pathway

Answer 7

• Tissue damage causes release of Thromboplastin
• Thromboplastin, Factor VII and Ca++ form = Thromboplastin/Factor VII Complex
• TBPN/FVII Complex activates Factor X
• Act.FX + FV + platelets phospholipids + Ca++ form = Prothrombinase

Question 8

Intrinsic Clotting Pathway

Answer 8

• Blood contact with collagen d/t damaged blood vessel wall activates Factor XII
• Act.FXII activates Factor XI
• Act.FXI + Ca++ activate Factor IX
• Act.FIX + Factor VIII + Platelet Phospholipids + Ca++ activate Factor X
• Act.FX + FV + platelets phospholipids + Ca++ form = Prothrombinase

Question 9

Vitamin K dependent clotting factors:

Answer 9

Prothrombin
Factor VII
Factor IX
Factor X

Question 10

What forms the Clot:

Answer 10

• thrombin converts fibrinogen to fibrin fibers

- fibrin clot is made up of fibrin fibers, platelets, blood cells, and plasma

Question 11

What retracts the Clot:

Answer 11

actin, myosin, thrombosthenin, and Ca++

Question 12

What forms the connective tissue in Clot:

Answer 12

fibroblasts which invade the clot and form connective tissue, enhanced by growth factors

Question 13

t-PA

Answer 13

• released by injured tissue and vascular endothelial cells

- converts plasminogen to plasmin

Question 14

Plasminogen

Answer 14

-inactive protein in clots which is converted to plasmin by t-PA

Question 15

Plasmin

Answer 15

• made from plasminogen by t-PA

- proteolytic enzyme which digests fibrin fibers and procoagulants

Question 16

Prevention of coagulation in Normal Blood Vessels:

Answer 16

1. smooth vascular endothelium
2. fibrin fibers absorb fibrin to prevent clot spread
3. antithrombin III combines/binds to and inactivates thrombin
4. endogenous heparin increases the effect of antithrombin III 100-1000x