Exam 3: Disorders of Hemostasis Flashcards
How is plasmin formed from plasminogen?
plasminogen along with factor XII and tPA (tissue plasminogen activator - also uses epithelial plasminogen activator)
What is one way to determine if clotting has happened?
measuring dimers
Which factors are dependent upon Vitamin K?
II, VII, IX, and X
A dog has low platelets, what is this called?
thrombocytopenia
Which pathway does APTT test?
The intrinsic coagulation pathway
Whyaren’t you worried about testing for factor III in the extrinsic coagulation cascade?
without FIII, you’re dead. only need to test for VII.
Bleeding disorders 1
What are three factors that deter coagulation?
think simply
a physical barrier
a non wettable surface (is thromboresistant)
and anticoagulant proteins
Bleeding disorder 1
What are three factors that encourage coagulation?
contraction of damaged vessel
exposure of collagen factors (reduced blood flow and reducsed shear stresss…clot stability)
production of von willebrand factor
bleding disorder 1
Which is more effective, primary or secondary hemostasis? why?
secondary is stronger. primary hemostasis only results in a platelet plug
Bleeding disorder 1
What steps are the involved in primary hemostasis - and what proteins and what is their role?
Adhesion: GP1b and vWF allow platelets to adhere
Release reaction: platelets release their granules (proteins talke about below)
Aggregation: aggregation of platelets and platelet plug (upregulation of ADP and vWF bridges)
Platelets faciliatate the coagulation reaction via scramblase
fibrinogen binds platelets to platelets
vWF binds platelets to collagen
Ca2+ is a cofactor in coagulation
ADP+++ helps platelets express a receptor to bind to other platelets
Bleeding disorder 1
What are the vitamin K dependent factors? What commonly used household item could interfere with this?
2,7,9,10
rodenticide
bleeding disorder 1
What one main enzyme is needed for the coagulation cascade?
thrombin
bleeding disorder 1
What are coagulation factors activated by?
exposed TF on endothelial cells, microparticles or extravascular fibroblasts.
also negatively charges surfaces like collagen
bleeding disorder 1
what factors are involved in the intrinsic, extrinsic, and common pathways?
intrinsic (inside walmart): 12,11,9,8
extrinsic: (3) and 7
common: 10,5,2,1
bleeding disorder 1
How does the common pathway go from factor 10 to a stable clot?
10 to 10a
(Ca, PF3, Va) - prothrombinase
2 to 2a
Fibrinogen to fibrin
(13a)
stable fibrin clot
bleeding disorder 1
What clotting factors does the liver make and which ones do macrophages also make?
1,8,9,11,12,13
2,5,7,10
bleeding disorder 1
can you run our of TFIII?
Not unless you’re dead
bleeding disorder 1
what is involved in the break down of clots?
antithrombin makes up 70% of the anticoagulant proteins, it inactivates thrombin and active factors 12,11,10,9
bleeding disorder 1
what can be mesured for evidence of clotting? What is this a process of?
D-dimers and Fibrin(ogen) degradation products
fibrinolysis - plasminogen to plasmin
bleeding disorder 1
What would make you weary in thrombosis?
peeing out antithrombin due to a damaged glomerulus.
what bleeding disorder is known as “clotting to death and bleeding to death at the same time?”
DIC, you’re clotting and running out of clotting factors. DIC can lead to liver failure.
Why is vitmanin K important for coagulation and what does it have to do with bile obstruction?
Vitamin K is responsible for creating the activation site on coagulation factors.
vitamin K is fat soluble. The bile emulsifies fats. without fat, there can exist a vitamin K deficiency.
What happens during thromboembolic disease?
pro-coagulant mechanisms overwhlem anticoagulant mechanisms and can cause vessel obstruction, poor or no perfusion and limb or organ dysfunction
What are some primary and secondary ways to evaluate hemostasis?
primary: platelet count on a blood slide and bleeding time
Secondary: checking APTT and PT time, quantifying fibrinogen and vWF.
not mentioned is ACT (Activated clotting time) that is an old test that is no longer used.
What are some clinical signs of a hemostasis disorder?
petechial (vascular and platelet abnormalities) and large hemorrahages (coagulation)
hemarthrosis is blood in the joints
What are some acquired causes for vascular disease? what would lab results look like?
vasculitis, cushings, scurvy
mainly normal. prolonged bleeding and normal to decreased platelet count
coag tests would be normal
You are looking at lab results for a hemostasis disorder. all coagulation tests are normal. there is prolonged bleeding and the ACT is slightly prolonged (can be normal to prolonged in current example). What may be the problem?
thrombocytopenia. these test don’t test for platelets, just the coagulation cascade. things are normal but something is not functioning.
What breeds are susceptible to type I vWF?
doberman pinscher
welsh corgi
german sheperd
golden retriever
poodle
What breeds are susceptible to type II vWF?
german shorthair pointer
What breeds are susceptible to type III vWF?
scottish terrier, shetland sheepdog, chesapeake bay retriever
What tests are normal for a vitamin k antagonism/ deficiency?
bleeding time, quantitative fibrinogen, and vWF
coagulation tests are prolonged
DIC is a nonspecific response to many things like…? How does DIC present on lab results?
extensive tissue damage: heat stroke, pancreatitis, sever hypoxia
endotoxemia/septicemia
IMHA
Neolpasia (progoagulant proteins)
vascular disease
& more!
everything prolonged… every time.
