Blood Stuff 1.1 Flashcards
Hemostase vs Coagulation
p3
Coagulation is one of the steps of hemostasis
Hemostasis involves all the parts (5 steps) involved in the clot formation
p3
Phase vasculaire
vasoconstriction of the vaisseaux as a response to a breach
This is just to reduce the overal flow of blood into the damaged site
THROMBOPOÏÉTINE
What it is and production
Synthesized in the liver
The liver produces a constant rate of thrombopoietine
If there are a lot of plaquettes in the blood, they will bind to trhombopoetine -> less thrombopoetine gets to the moelle osseuse -> less plaquettes are synthesized and vice versa
a mechanism of regulation
Facteur von Willebrand
Protein that travels in blood and binds on damaged blood vessels
Specifically binds to exposed collagen
When bound, plaquettes can recognize it (FVW) and bind to it to form a blood clot (coagulate)
This step is called addhesion via
Ib-V-IX receptors
When bound, the plaquettes send signals and express Receptor IIb-IIIa
This step in important for aggregation
ATTENTION!!
Récepteur Ib-V-IX
- responsable de l’adhésion
- médiateur : fVW
Récepteur IIb/IIIa
- responsable de l’aggrégation
- médiateur : fibrinogène
Recepteurs Ib-V-IX vs IIb-IIIa
Ib-V-IX receptor is important for initial adhesion where as IIb-IIIa is important for aggrgation
1b-5-9 are the facteur van willbran sensors!
The most important product of coagulation?
Fibrin
THE GLUE
It is the goal of coagulation which solidifies the platelets!!!
Why are thre so many facteurs de coagulation
Because coagulation is a dangerous process that needs to be well controlled
Given the cascade of coagulation, what is the ultimate goal?
The transformation of Fibrinogen into Fibrin
La voie commune de la cascade and the involved facterus
10(X) + 5(V) -> 2(thrombin’IIa) -> 1(fibrin; Ia)
Role of thrombin
It is the facteur that allows to go from Fibrinogen -> Fibrin
Temps de prothrombine
Addition of Facteur tissulaire (FT) + Calcium -> activation of extrintic route -> fibrinogene and then fibrin
We can measure the time to get fibrin or the clump as the time for coagulation
PT = play tenis = outside= exogene route
Temps de céphaline active - TCa
Partial thromboplastin time
Similar to the temps de prothrombine, this route tests the speed of the intrinsic route
requires phospholipds
Partial thromboplastin time -> Play Table Tenis -> inside -> intrinec
Role of calcium
Coagulation cannot occur in the absence of Calcium
Where do plaquettes come from?
megakaryocytes
True or False,
Plaquettes are the most important and strongest response to stop bleeding
False,
Platelets is liek the first step. You need coagulation!!
Thrombin role in the coagulation cascade?
Activation du fibrinogène
* Activation du fXIII
* Activation rétrograde des
facteurs V, VIII, XI (like a bomb reaction; more more more; amplification)
What is the most important factor to initiate the coagulation cascade? ?
Facteur tisulaire
Can you study facteurs de coagulation in serum?
NOPE
Serum = no anticoagulant
Ne contient pas les facteurs
de coagulation (car
consommés dans le caillot)
You are doign a prothombin time and céphaline active time. You notice that both of them work well but the patient still has coagulation problems. WHy?
The patient likely has an issue in the voie commune and his intrinsic and extrinsic pathways work well
What is Rapport international normalisé (RIN)?
Key to normalize values across laboratories in the efficency of warfarine
Temps de prothrobmotin standartize following a prescription
Retraction du caillot
Step 4 of coagulation
This is a step that involves the post activation of the plaquettes by thrombin.
This makes the plaquettes explode and have projections that will grab both ends of the damaged vaisseau and try to bring them together to close the hole.
The most important player in the destruction of the caillot?
Plasmin
It can break fibrin bonds (fibrinolyse) and leads to the breakage of the clot after the closure of the vessel
Role of facteur XIII
Glue fibrins together
Caillot rouge vs caillot blanc
53 minutes
Caillot Rouge
Globules rouges
« coincés » dans un
treillis de fibrine
Caractéristique des
thromboses veineuses
Caillot Blanc: Thrombose arterielles
Antithrombine and what amplifies it
Prevents the activation of thrombine
fortement amplifiée par l’heparan sulfate (héparine)
Complexe protéine C activée et protéine S
BLockers of coagulation
Clivage enzymatique des facteurs Va/VIIIa
Protéine C activée détruit
les facteurs de coagulation
là ou ils ne sont plus utiles
thrombomoduline
Factor that is found on healthy endothelium and that binds thrombonin preventing its activity
This blocked thrombonin has now an effect of activatin protein C, which as we know:
Protéine C activée détruit
les facteurs de coagulation
Heparin
Medication that blocks coagulation
Antithrombine est fortement amplifiée par l’heparan sulfate (héparine)
Augmente l’effet inhibiteur de
l’antithrombine
La faoi est l’endroit de synthèse de presque tous les
facteurs de la coagulation
! Exception and what is the problem?
VIII et von Willebrand
IF a ptn has a cirrose du foie they will have lowered coagulation factors but not von Willebrand or VIII
Hemophilie A vs B
Déficit en facteur VIII (hémophilie A) : 80%
! Déficit en** facteur IX **(hémophilie B) : 15%
Hemophilie Transmission
EXAM EXAM EXAM
Transmission is done via chromosome X
A boy has an X and a Y chromosome
A girl has two X chromosomes
Must understand that this affects mainly guys. The reason is that both chromosome X must be affected in a girl for her to be sick. Whereas a guy only has one chromosome so, just getting one X is sufficient.
If a father is touched by hemophilie, it’s son will never never have hemophilie because the affected chromosome X is not transmitted. Intead, the boys take the healthy chromosome X from the mother
However, the daughters will 100% carry hemophilie because they must take one X chromosome from father and one from mother. Again here, they carry the mutation but it is recessive i,e not showing.
On the other hand, if the mother is affected, well there is a 50% chance of transmitting the affected X chromosome to ether a guy or a girl so 50 50 chance for both guy and girl to hav ethe mutation.
But here again, the girl that takes the mutated chromosome X will only carry and not show since the other chromosome comes from the father
On the other hand, the affected boys will display hemophilie because they only have one X
Maladie de von Willebrand
In contrast to hemophilie, this is autosomale dominante
This means, having one bad chromosome is sufficent to produce symptoms and so it affects girls and boys
Anti-vitamine K and effect
This is a medication by the name of Coumadin
It blocks vitamin K activity
Vitamin K is key for facteurs II, VII, IX et X
which are essential across the coagulation path
i.e, blocks coagulation
