1- Haematological System 2 Flashcards
What is the function of platelets (thrombocytes)?
Help stop blood loss from damaged vessels by forming a platelet plug and promote blood clotting
What stimulates myeloid stem cells to produce platelets in bone marrow?
Thrombopoietin
What is thrombopoiesis?
The process of making platelets
What is Haemostasis?
Haemostasis is a process to prevent and stop bleeding
What is haemorrhage?
The loss of a large amount of blood
Name 2 types of granules in platelet plug formation
1- Dense granules (ADP, ATP, Ca2+, serotonin, fibrin-stabilizing factor, and enzymes that produce thromboxane A2)
2- Alpha granules (clotting factors)
Platelets bud off from which cell?
Megakaryocytes
Name 3 steps in platelet plug formation
1- Platelet adhesion (to collagen fibres)
2-Platelet release reaction (liberated ADP, serotonin and thromboxane A2)
3- Platelet aggregation (platelet plug)
Name 3 steps in a clotting cascade
1- Formation of prothrombinase
2- Prothrombinase and Ca2+ convert prothrombin into thrombin
3- Thrombin converts soluble fibrinogen into insoluble fibrin threads
Through which pathway does prothrombinase form the quickest?
Extrinsic pathway
Two positive feedback effects of thrombin?
1- Thrombin accelerates formation of prothrombinase
2- Thrombin activates platelets to release phospholipids
What if fibrinolysis?
Fibrinolysis is the dissolution of a clot.
What is thrombosis?
Thrombosis is the clotting in an unbroken blood vessel and involves the intrinsic pathway
What is embolus?
Embolus is a thrombus (clot), bubble of air, fat from broken bones, or piece of debris transported by the bloodstream that moves from its site of origin
What are agglutinogens?
Agglutinogens (or antibodies) are surface antigens on erythrocytes
They determine blood type A, B, AB or O
