Hemostasis Flashcards
Coagulation
What is hemostasis?
The process by which the body control bleeding and maintains blood in a fluid form.
Hemostasis is composed of? (4)
- Vascular system (blood vessels)
- Platelets
- Coagulation (factors)
- Fibrinolysis
What activates the primary hemostasis system? What 2 functions are primarily involved?
Activated by small vessel damage. Vasoconstriction Platelet function
What activates the secondary hemostasis system? What 2 functions are mainly involved?
Activated by major trauma, surgery, or hemorrhage Coagulation proteins Enzymatic reactions
What is vasoconstriction?
ability of small vessels to contract which decreases the diameter of of blood vessels and decrease blood flow.
What do platelets do?
Form a platelet plug
Coagulation is is dependent on a series of _______ that take part in a series of ______ ______ resulting in the formation of ______.
Proteins enzymatic reactions Fibrin
The secondary system also includes _______ which is clot _____ once the blood loss has stopped and the vessel repaired.
Fibrinolysis dissolution
The vascular system prevents bleeding through? (3)
Vessel constriction Activation of PLTs Activation of coagulation system
The vessel wall contains Fibrous tissue consisting of?
Collagen and elastic fibers smooth muscle
An injured vessel exposes collagen which reacts with PLTs via ____ _____ _____
von WIllebrand factor
What is the life span of a PLT?
7 - 10 days
What stimulates PLT production?
Thrombopoietin
PLT parent cell is the _______ that undergoes ________.
Megakaryocyte Endomitosis
There are no significant # of PLTs in bone marrow, _____ in circulation, and _____ in spleen.
67% BM 33% Spleen
What are the 3 phases of PLT function?
Adhesion Amplification Aggregation
What happens during PLT adhesion? What is required? (2)
PLTs adhere to collagen and change shape (when they interact) Required: von Willebrand factor (vWF) and Glycoprotein 1b (GpIb) Secretion of PLT and clot activating substances.
What happens during Amplification? What helps this?
Secreted substances recruit more PLTs to aggregate. Thromboxane A2
What happens during Aggregation and what is used?
PLTs adhere to other PLTs Uses GpIIb and GpIIIa to adhere with oth. PLTs via plasma proteins such as fibrinogen.
T/F: PLTs play and important roles in the formation of the primary PLT plug (primary hemostasis) as well and the coagulation cascade (secondary hemostasis)
True
PLTs serve as the site for?
Coagulation
What are coagulation factors?
Blood proteins that conclude with an insoluble fibrin clot
Where are all coagulation factors produced? Which one is not produced here?
Liver EXCEPT factor VIII
What are the two different pathways for clotting?
Extrinsic (Tissue factor pathway): Rapid response to tissue injury Intrinsic (Contact activation pathway): slower response, but quantitatively more significant.