The process of blood clotting, or hemostasis, stops blood loss
platelet aggregation
property of platelets to adhere to an injured surface and then attract other platelets, which clump together or aggregate at the area, plugging up an injury to the vascular system
clotting factors
proteins in the plasma that serve to activate various parts of the blood clotting process by being transformed from inactive to active forms. Also known as coagulation factors.
thromboxane A2 and serotonin
causes vascular spasms
coagulation phase
3rd hemostasis step: blood clotting enzyme chain reaction, ending with *fibrinogen converted into fibrin*
platelet adhesion
Platelets stick to exposed collagen underlying damaged endothelial cells in vessel wall
prothrombin activator
a protein formed by clotting factors from damaged tissue cells and platelets; it converts prothrombin into thrombin, a step essential to forming a blood clot
Platelets release
adenosine diphosphate (ADP), (2) thromboxane A2 and serotonin, (3) clotting factors; (4) platelet-derived growth factor (PDGF), (5) calcium ions,
clot retraction
after coagulation, platelets contract pulling torn blood vessel together
clotting factors
any of the various plasma components involved in the clotting process
platelet phase of hemostasis
attachment of platelets to sticky endothelial surface marks the beginning of this phase - begins within 15 seconds of the injury occurrence
extrinsic pathway of coagulation
begins when damaged endothelial cells or peripheral tissues release Factor III, also termed tissue factor or thromboplastin
Common pathway factors
begins when enzyme complexes from either pathway activate Factor X
Intrinsic pathway of coagulation
begins with the activation of proenzymes (usually Factor XII) exposed to collagen fibers at the injury site
Vascular phase of hemostasis
causes contraction of a vessel wall, referred to as a vascular spasm, decreasing the diameter of the vessel - lasts about 30 minutes
calcium ions
required for platelet aggregation and in several steps in the clotting process
Platelet-derived growth factor (PDGF)
stimulates division of smooth muscle cells and fibroblasts to rebuild blood vessel wall
Adenosine Diphosphate (ADP)
stimulates platelet aggregation and secretion
Hemostasis
to stop or control bleeding establishes a framework for tissue repairs.
Factors Limiting Clot Growth or Formation
two homeostatic mechanisms prevent clots from becoming large -swift removal and dilution of clotting factors -inhibition of activated clotting factors
Hemostasis Phase
vascular phase, the platelet phase, and the coagulation phase