Clotting Cascade Flashcards
Thrombin function
Recruit even more platelets and cause fibrins to form a mesh work over the platelet aggregation
CASE 1 68yo male on warfarin therapy for 5 mos for many past strokes, he has fallen and fractured his hip. Warfarin is discontinued 48hrs before surgery for what reason
48hrs is the time required for full expression of the Factor 2,7,9,10 genes
Reason warfarin should be discontinued 48hrs prior to surgery
Warfarin DECREASES VIT K
VIT K is needed for gamma-glutamylcarboxylase since it inhibits epoxied hydrolase
What does Gamma-glutamylacarboxylase do
Catalysts many Ca bonding proteins (FACTORS 2, 7, 9, 10 + PROTEIN C and PROTEIN S) = coagulation
(Synthesis of these take 48hrs, and breakdown of them also takes 48hrs by warfarin)
Factor 2 half-life
60hrs
Factor 9 half-life
24hrs
Factor 10 half-life
40-60hrs
What activated the extrinsic pathway
+ which important factor
External Trauma when blood escapes the vascular system
FASTER
*FACTOR 7
What activates the intrinsic pathway + which important factor
Trauma inside vascular system
(Platelets, exposed endothelium, chemicals, collagen —> activate)
SLOWER
*Factor 8, 9, 11, 12
INTRINSIC PATHWAY STEPS
- Kallikrein activates F12 (hageman factor)
- F12a activates F11
- F11a activates F9*
- Thrombin activates F8*
- F10 is added *
=TENASE COMPLEX
Thrombin is what factor
Factor 2
Intrinsic TENASE complex includes
F8a
F9a
F10
EXTRINSIC PATHWAY steps
- Tissue injury activates Thromboplastin
- Thromboplastin activates F7*
- Tissue Factor is added
- F10 is added
= TENASE COMPLEX
Extrinsic TENEASE complex
F7a
F10
Tissue Factor
COMMON PATHWAY steps
- Factor 10 on TENASE complex is activated by CA+2
- F10a uses Ca+2 + F5a to activate Prothrombin (F2) to Thrombin (F2a)
- F2a activates F5
- F2a uses Ca+2 to activate F8 + make FIBRIN *
Primary Hemostasis
Platelets aggregate to form platelet plug (block hole) WEAK -vascular contraction -glycoproteins R on platelets - collagen +fibrinogen
Secondary Hemostasis
Fibrin Mesh forms of the platelet plug by coagulation cascade
- STRONG
- fibrin
- subendothelial collagen
- Thromboplastin
- coagulation factors
- fibrinogen
MAJOR ROLE OF THROMBIN *
- Fibrinogen to Fibrin
2. F13 to F13a
How is the Fibrin cross linked
F13a and Ca+2 cause the fibrin to cross link
3 other roles of thrombin
- F5a
- F8a
- Activation of platelets
2 anticoagulants and what there major effect is
- Hydroxycoumarins
- Indanediones
* INHIBIT VIT K
Hydroxycoumarins example
Warfarin
Activation of VIT K steps (2 steps)
- 2,3-epoxied reductase + NADH : 2,3-epoxide—> QUINONE
- Quinone reductase : quinone —> QUINOL * in liver
* LIVER : quinone —> quinol (active)
What does the VIT K (QUINOL) do
Uses gamma-glutamyl carboxylase* to ACTIVATE Factors 2, 7, 9, 10, Protein C and Protein S
How does Warfarin inhibit coagulation
It INHIBITS the 2,3-Epoxide Reductase which blocks the conversion of VIT K cycle to convert GLUTAMATAE RESIDUES ——> gamma-carboxyglutamate residues (Factors 2,7,9,10, proteins C +S)* + PROTHROMBIN*
For patient with elevated PT or mucosal bleeding what shouldI give them
400mg VIT K or daily 50mg-100mg
Peak plasma warfarin happens when
3hrs after Ingested
S-Warfarin
Binds to albumin tighter
*5x more potent
R-warfarin
Highly binds to proteins
Not as potent
Which types of drugs will inhibit or increase the ability of warfarin to work
Drugs that compete to bind to albumin or drugs that inhibit warfarin metabolism
Protein C and Protein S function
ANTICOAGULATION
——I F5a + F8a
= LOWER THROMBIN FORMATION*
Low Protein C cases
Significant risk for venous thrombosis
With Patient taking Warfarin what should you look our for
Any bleeding
Diet should have VIT K (green leafy veggies)
Carry ID card
Hemophilia A
X F8 most severe + more common
* cant form Fibrin clot (Hemostasis) + no TENASE COMPLEX
Hemophilia B
X F9
Also called Christmas Disease
