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VetTech Hemostasis,
coagulation factors homostasis cascade vessles lab work handling diseases
Question | Answer |
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COAGULATION | AKA: blood clotting. A protective mechanism that minimizes blood loss when blood vessels are ruptured. Phase of hemostasis which the platelet plug changes into a blood clot, it is done by clotting factors. |
In normal coagulation there is a very finely controlled system that: | Prevents blood loss Maintains blood flow Allows the healing and repair of injured vessels Too much or too little hemostasis=BADNESS |
Hemostasis | termination of bleeding by mechanical or chemical means or by the coagulation process of the body. |
Defects of hemostasis | Include excessive hemostasis, which results in clots, or excessive bleeding Disorders of hemostasis can be life threatening Also, it pretty much sucks to discover an animal has a hemostatic disorder when they are in surgery! |
Componants of Hemostasis | Circulating coagulation factors (proteins) These form insoluble fibrin, which is sort of a net for platelets Circulating platelets (thrombocytes) The vessel wall |
Coagulopathy | Refers to excessive bleeding that results from absence of or abnormal function of one or more coagulation factors |
Coagulation factors are present in plasma in very _____ concentrations | Small |
Coagulation factors are activated mostly by | damaged endothelial cells These proteins are ONLY exposed when endothelial cells are damaged. This prevents activation of coagulation factors when there is no need! |
Coagulation Factors | Once they are initially activated, coagulation factors undergo a “cascade” or “waterfall” where additional factors are activated and amplified The grand finale is conversion of fibrinogen to fibrin, and the formation of a stable fibrin clot |
Clotting steps | 13 |
Intrinsic | Coagulation that occurs in the blood vessels |
Extrinsic | Coagulation that occurs within the tissues |
Common pathway | The final culmination of both pathways coming together, formation of the fibrin clot |
The All Important Vitamin K | Normal coagulation factor activity absolutely REQUIRES Vitamin K |
Vitamin K serves as a cofactor for formation of coagulation factors | II, VII, IX and X Also anticoagulant proteins C and S Without Vitamin K, the precursors to II, VII, IX, X, C and S are formed but lack activity, or are nonfunctional |
PIVKA | Proteins in vitamin K absence/antagonism Can test for these! PIVKA testing used when rodenticide toxicity is suspected |
Giving Vitamin K | Given to animals who have suspected or confirmed rodenticide toxicity Can be given SQ, IM or orally IM=high incidence of acute allergic reaction, BLEEDING Remember if given orally needs to be with food since Vitamin K is a fat soluble vitamin! |
Platelets | Fragments of megakaryocytes CRUCIAL to hemostasis Responsible for the first, initial stopping of blood flow Platelets adhere to damaged endothelium Accomplished by binding of a surface receptor 1b to von Willebrand factor (vWF), which binds to collage |
Platelets forming plug | Platelets then adhere to one another When they stick together they swell, form little feet, or “pseudopodia” to grab onto each other Platelets contain granules that when released stimulate further platelet recruitment and aggregation |