blood 5 Flashcards
what are plateletsF
Fragments of megakaryocytes with blue staining out region and purple granular center
what enzyme regulate platelet formation
thrombopoeitin
what is the point of platlets
clotting factors and enzymes
temporary plug sealing broken blood vessels
how are platelts that do not clot keep inactive
by NO (nitric oxide) and prostacyclin release from endothelium
what is the life span of a platelet
about 10 days
what is the stem cell of a platelet
hemocytoblast
what is the development pathway of platelets
hemocytoblast –> megakaryoblast –> Promegakaryocyte —> Megakaryocyte –> Platelets
what is hemostasis
a series of reactions for stoppage of bleeding
what are the three phases of homeostasis
vascular spams- smooth muscle immediate vasoconstriction in response to injure
platelet plug formation- platelets stick and release chemicals for nearby platelets to stick
coagulation (blood clotting)- fibrin forms a mesh trapping RBCs and platelets forming the clot
when does vasoconstriction happen?
in response to injury, trigger by damage and chemical from ECs and platelets, pain reflex
what are platelets sticking to?
they don’t stick to blood vessels or each other they stick to exposed collagen fibers forming a plug (VWF)
how do platelets attract more platelets?
by releasing serotonin and ADP
what are platelets
Fragments of megakaryocytes with blue staining out region and purple granular center
upon damage to Blood vessel endothelium platelets will
adhere to collagen (VWF)
release sertonin and ADP to attract more
release and stimulated by thromboxane A2
why don’t platelets plugs happen everywhere
limited to area of injury by presence of NO and prostacyclin released by endothelial cells
