Blood (HLB) Flashcards
What is haemostasis?
Process of stopping bleeding
What are the stages of haemostasis?
1) Vasoconstriction
2). Primary haemostasis = formation of platelet plug
3). Secondary haemostasis = reinforcement of platelet plug
What is the name of the process which produces platelets?
What is the receptor involved in this?
What cell do platelets originate from?
Thrombopoiesis
TPO
Megakaryocytes
What is the name of the process which produces RBCs?
Which receptor is involved in this?
Erythropoeisis
EPO
What causes vasoconstriction when blood vessels are injured?
Endothelial cells produces endothelin - this causes regional arterioles to constrict.
Endothelial cells that are injured also produce thromboxane A2 and 5HT - these cause nearby smooth muscle to contact, also increasing vasoconstriction.
What are the three steps of platelet plug formation?
Platelets adhere to a BV wall
Platelets are activated
Platelets aggregate
How to platelets bind to an injured blood vessel wall?
Beneath the wall lies collagen which has been exposed. VWF can bind to this collagen - and then it attaches to platelets via the GP1b receptor
When platelets are activated, what do they release?
Granules of ADP, thromboxane A2 and 5HT
How does platelet aggregation occur in an injury?
ADP & Thromboxane A2 are released from bound, activated platelets. These attract other passing platelets to the site of injury.
Platelets can then bind to each other via GP2b3a receptors - fibrinogen binds them together.
Which disease can cause a defect in the receptor GP1b on platelets - causing haemophilia.
Bernard-Soulier syndrome
Which disease can cause a decrease in levels of VWF?
VW disease
What is thrombocytopenia?
A decreased amount of platelets in the blood - can cause inability to clot properly.
Which disease can affect the platelet receptor GP2b3a - thereby reducing coagulation?
Glanzmann’s thrombasthenia
What are the three pathways of the coagulation cascade?
Intrinsic
Extrinsic
Common
Which factors are involved in the intrinsic pathway?
12, 11, 9, & 8