Heme 2.5 Flashcards
how is any local bleeding “arrested”
intereaction between platelets and blood vessel endothelial cells, fallowed by cascade of coagulation
what is hemostasis desiged to ensure
there is no major leakage of blood following injury and consists of a complex system proteins and enzymes
what is thrombosis
clots forming to easily
how many platelets can a single megakaryocite produce
around 3000
what amount of platelets are pooled in the spleen
about 20-30%
what is the average lifespan of a platelet
5-20 days
what artery layer is important for hemostasis
connective tissue layer (within the tunica intima)
what triggers vasoconstriction in arteries and vains
the direct injury itself
sympathetic nervous system
descrive platelet plug formation
- aggregation of platelets
- platelets stick to exposed collogen, swell, and form spiked process
- platelet plugs are effectin in preventing blood los due to small injuries
how do platelets tick to exposed collagen of damaged endothelium
GPIa receptors (GP=glycoproten)
what is von Willebrand’s Factor (vWF) and what receptor does is use
via GBIb receptors, it speciffically causes platelets to attach firmly to and spread across the damaged endothelial surface.
what happens to platelets when they adhere
the will indergo major structural changes and deformities
what three things are stored within platelet granules
ADP
Thromboxane (TA2; TXA2; a prostaglandin)
serotonin (5-HT)
what does fibrinogen bind to to link platelets together
GPIIb/IIIa
what is the process of the cuagulation phase
- occurs either to reinforce a platelet plug of to stop blead when a platelet plug fails
- involved numerous clotting factors which are often indicated by roman numerals
- most(not all) clotting cafros are proteins and are synthesized by the liver
what are most clotting factors existing as
zymogens (inactive form in the blood)
clotting factor I (name and location
fibrinogen, liver
CF II
prothrombin, liver
CF III
tissue factro or thromboplastin, perivascular tissue
CF IV
calcium, Plasma
what are the vitamin K dependant CF
II, VII, IX, X
CF V
proaccerlerin, LIVER
CF VII
proconvertin (stable factor), liver
what is the blood clotting cascade
comprises intrinsic and extrinsic pathways- both are initiated mimultaneously and lead to final common pathway
intrinsic pathway
initiated within the blood
extrinsic pathway
initiated outside the blood
what does the common pathway begin
when factor X is initiated
what are three “natural” anti-coagulants
- thrombomodulin
- antithrombin III (or just antithrombin)
- Heparin cofactor II
what is inside a true clot
red cells, fibrin and proteins
Where can Von Willebrands factor be found
a protein found in plasma, platelets, and the walls of blood vessels
