Health and Disease Week 5 Flashcards
What is blood production controlled by?
multiple protein cytokines (release by WB cells) and growth factors
What detects blood vessel damage?
platelet surface receptors
What do platelets secrete? Why?
soluble factors to activate neighbouring platelets
What is required for a clotting cascade?
multiple blood proteins
What does thrombopoietin do?
regulate production of platelets
What does erythropoietin do?
regulate production of erythrocytes
What are the major precursors of platelets?
megakaryocytes
What kind of cells give rise to haematopoietic precursors of blood cells?
pluripotent stem cells
What creates a bruise?
when blood vessel endotheliums become damaged and blood leaks into surrouding tissues
What is the scientific name for blood clotting?
haemostasis
What 2 stages can clotting be broken down into?
- primary haemostasis
- secondary haemostasis
What happens in primary haemostasis?
platelets form a plug and are attracted to site of damage
What happens in secondary haemostasis?
a blood clotting mechanism is used to transform and stabilise the weak platelet plug into a clot by a fibrin network
What is the 1st step of platelet plug formation?
adhesion
What are the steps of adhesion in platelet plug formation?
- damage to endothelium cells exposes subendothelial tissue which is made up of collagen fibres
- collagen activates platelets and they adhere to these collagen fibres via an intermediate protein called von Willebrand factor (vWF)
- platelets binding to collagen causes a release of ADP and serotonin from their secretory vesicles, resulting in more platelet activation
What is the 2nd step of platelet plug formation?
platelet activation
What are the steps of platelet activation?
- release of ADP and serotonin from vesicles
- this causes change in shape and surface protein expression of platelets
What is the 3rd step of platelet plug formation?
platelet aggregation
What are the steps of platelet aggregation?
- platelets adhere to each other to form a plug
- synthesis and release of thromboxane A2 from arachidonic acid enhances more activation and aggregation
What stabilises the platelet plug?
fibrinogen bridges that form when receptors in the platelet surface become exposed during activation
What causes contraction of the plug?
actin and myosin
What do healthy endothelial cells do?
synthesis and release of Prostacyclin (PGI2) and nitric oxide, which both inhibit platelet activation
What is the scientific name for a clot?
a thrombus