17.2 Flashcards
(31 cards)
what are band cells
immature/brand new versions of a granulocyte
what is leucopenia
formation of wbc, regulated by the production of interleukins and colony stimulating factors
what are the 2 pathways of differentiation of hemocytoblasts
lymphoid stem cells that rise to lymphocytes
myeloid stem cells that rise to all other wbc
how long do monocytes last?
months
how long do lymphocytes live for
months-years
what is leukopenia
abnormally low wbc counts
what are leukemias
cancerous conditions in which clones of a single wbc remain unspecialized and divide out of control
what are the functions of platelets
critical in clotting process forming a temporary seal when blood vessels break
what is thrombopoeiting
hormone that regulates the formation of platelets
what is another name for platelets
megakaryocytes
what is haemostasis and what are its steps
process of preventing blood loss
vascular spasm
platelet plug formation
coagulation
what is haemostasis and what are its steps
process of preventing blood loss
vascular spasm
platelet plug formation
coagulation
what are vascular spasms
immediate vaso-constriction response to blood vessel injury that reduce blood flow until the other mechanisms can begin
what occurs during platelet blood formation
when blood vessels break the collagen in its walls attract and activate platelets
when activated they sweel and become spiked and sticky and adhere to each other to close the damaged walls
what occurs during coagulation
process in which blood is transformed from liquid to a gel, reinforcing platelet plugs with fibrin threads to seal larger vessel breaks
what are the factors that inhibit clot formation
anticoagulants
what are the factors that promote clot formation
clotting factors/procoagulants
what are the 2 pathways to the formation of prothrombin activator
intrinsic - factors are present within the blood, slower clotting process and may be triggered by negatively charged surfaces such as activated platelets
extrinsic - triggered by endothelium derived glycoprotein (TF - tissue factor) and can occur rapidly bypassing some steps of the intrinsic pathway
why is prothrombin activator necessary in clotting formation
it is necessary because it leads to the production of active enxyme thrombin which converts soluable fibrinogen into fibrin
why is fibrin necessary in clotting formation
fibrin causes plasma to become gel like and form the fibrin mesh that forms a clot
what is clot retraction
process in which contractile proteins within platelets contract and pull neighbouring fibrin strands squeezing plasma from the clot and pull damaged tissue together
what stimulates repair of skin
platelet derived growth factor to stimulate endothelial cell division
what is fibrinolysis
the removal of unneeded clots through the action of fibrin digesting enzyme and plasmin
what can limit clot formation
rapidly moving plood and disseminates clotting factors before they can initiate a clotting cascade
factors can be limited by other compounds in the blood
