Hematology (Strauss) Flashcards
What are the 4 phases of blood clot formation?
- Vascular
- Platelet
- Coagulation
- Fibrinolytic
What is the phase of clot formation where blood vessels contract (collagen in the vessel contracts to stop the bleeding via a local myogenic spasm)?
Vascular phase
What is the phase of clot formation where platelets distort, clump, and stick to form initial platelet plug (will distort due to the action of instigators)?
Platelet phase
What is the phase of clot formation where blood profactors become factor and react to form fibrin (the basis for the clot)?
Coagulation phase
What is the basis for the blood clot?
Fibrin
What is the phase of clot formation where the clot dissolves to allow healing?
Fibrinolytic phase
What is the local autocoid that is released from traumatized tissue how long do they last, and where are they eliminated?
Synthesized in bone marrow by megakaryocytes
1-4 micrometers
7-10 day half-ife
Eliminated by macrophages in the spleen
Can platelets reproduce?
No. They have no nuclei.
Can platelets contract?
Yes. They have throbosethin, actin, and myosin, which are contractile proteins.
Why is a dental extraction the ultimate challenge to the patient’s ability to clot?
Can’t get primary closure.
Why are scaling and root planing potentially devastating if the patient can’t stop bleeding?
Can’t just easily stop the bleeding, plug it, close, etc.
The platelet surface is coated with what to keep them from adhering to normal endothelium but allows them to adhere to damaged cell walls?
Glycoprotein
Platelets have what on the membrane that activates multiple stages of the coagulation process?
- Phospholipids
2. Platelet Factor 3 (PF3)
Why is the half-life of a platelet and important consideration?
Factor in when taking patient off anticoagulation meds
What is released from platelets and endothelial cells to link the platelets with exposed collagen fibers?
Von Willibrand factor
How long until the initial platelet plug occur?
5-12 minutes
Is the platelet plug strong?
No, but it gives you initial stability
What can cause the fibrin clot to be formed?
- Damaged endothelium
2. Factors in the blood
How long does the fibrin clot take to form?
Up to 6-8 hours
How long with the fibrin clot (a scab) stay there?
A few days
Plasminogin becomes plasmin and dissolves what?
Fibrin clots. This is a process that is occurring all the time.
What is an irreversible platelet poison?
Aspirin
How long does the analgesia of aspirin last?
4 hours
For how long does aspirin irreversably poison your platelets?
7 days
What are necessary for platelet aggregation and activation of nearby platelets in order for the number of activated platelets to increase successively?
- ADP
2. Thromboxane A2
Initially, what activates platelets in the area of a wound?
Exposed collagen fibers in damaged vessel walls
What makes the platelet plug, which is loose at first, stronger?
Fibrin threads from coagulation phase interweaving through the platelet plug
What are 2 major parts of the coagulation system?
- Procoagulants
2. Anticoagulants
In normal blood flow, what part of the coagulation system predominates?
Anticoagulants
What are 2 things that start the coagulation process?
Material from damaged vessel walls in blood (things in blood that notice material or damage)
What are 2 ways to get to the formation of prothrombin activator complex in the coagulation cascade?
- Extrinsic pathway
2. Intrinsic pathway
What is the purpose of the prothrombin activator complex in the coagulation cascade?
Convert prothrombin (Factor II) to Thrombin (Factor IIa)
Which system includes XII, XI, IX, VIII?
Intrinsic system
Which system is mostly VII?
Extrinsic system
Which pathway includes X, V, IV, III?
The common pathway
What is the purpose of Thrombin in the coagulation cascade?
Converts fibrinogen (Factor I) to Fibrin (Factor IA)
What is the purpose of Fibrin (Factor Ia) in the coagulation cascade?
Form a meshwork around the platelet plug
The extrinsic and intrinsic pathways of coagulation meet where?
The common pathway
What factors are in the common pathway?
Factors 10, 3, 4, 5, 2, 1
What does the common pathway produce?
Factor 10 and Factor 5 and phospholipid form the prothrombin complex to convert prothrombin (Factor II) to Thrombin (Factor IIa) which converts Fibrinogen (Factor I) to Fibrin (Factor Ia)
What is the only factor in the extrinsic pathway for coagulation?
Factor 7
What stimulates factor VII of the extrinsic pathway?
Release of Factor 3 (Tissue thromboplastin) from traumatized tissue (Re: 3+7 = 10, 10 is the common pathway)
What are the factors in the intrinsic pathway?
12, 11, 9, 8
What stimulates the intrinsic pathway and what is the factor that starts off the intrinsic pathway?
Collagen from vessel wall and injured tissue activates factor 12
Collagen from the vessel wall and injured tissue not only activates Factor 12 of the intrinsic pathway, they also activate what?
Platelets. The platelets fwill produce PF3 which will come back into play at the end of the intrinsic pathway as Factor 9a interacts with Factor 8 and PF3 to stimulate Factor 10 of the common pathway
Factor 12 activated, becomes Factor 12a, and requires what two things to activate Factor 11?
- Kininogen
2. Prekallikrein
Once Factor 11 is activated by Factor 12a + kinenogen + prekallikrein, and becomes factor 11A, it activates what Factor next in the intrinsic pathway?
Factor 9
Factor 9 becomes Factor 9a after activation by Factor 11a, and Factor 9a activates what next and in what pathway?
Activates Factor 10 of the common pathway
What must factor 9a have help in order to activate Factor 10 of the common pathway?
Factor 8 and PF3
When Factor 10 is activated by Factor 9a + Factor 8 + PF3, what is created?
Factor 10 + Factor 5 + phospholipids form Prothrombin activator to activate Prothrombin (Factor II) to Thrombin (Factor IIa) which will activate Fibrinogen (Factor I) to Fibrin (Factor Ia)
Why do we want to know if a patient has liver disease?
Every proenzyme (except for Factor 8) are made in the liver. If the function of the liver is not good, you won’t have good clotting.
Why does cancer affect clotting?
Radiation therapy affects bone marrow, where the clotting happens
What is required for the Prothrombin activator (Factor 10 + Factor 5 + phospholipids) to convert Prothrombin (Factor 2) to Thrombin (Factor 2a)?
Calcium
Where is prothrombin (Factor 2) synthesized and on what vitamin does it depend?
- Liver
2. Vitamin K
What substance is Thrombin (Factor 2a)?
Proteolytic enzyme that acts on fibrinogen (Factor 1)
Fibrin (Factor IA) is syntehsized where and is it a monomer or a dimer?
- Liver
2. Monomer that polymerizes with other fibrin monomers to form fibrin fibers
As a dentist, can you order a CBC?
Yes
Are the initial bonds between fibrin (Factor Ia) monomers strong or weak?
Weak
What strengthens the bonds between fibrin monomers as they polymerize to make fibrin?
Fibrin stabilizing factor
Where is fibrin stabilizing factor released from?
Plasma globulin
Platelets