WEEK 5 - Lect 9: Haematology II

• Pre clarifier: this lecture covers two man topics (haemostasis and blood groups)

  
• HAEMOSTASIS ILO:

  (By the end of the part on haemostasis you should be able to answer the following questions)

  
• HAEMOSTASIS ILO:

  (By the end of the part on blood groups you should be able to answer the following questions:)

  
• Part 1: Haemostasis-how our blood forms a clot -> name the three main elements of The haemostatic response


  • Vasoconstriction - blood vessels
  • platelet adhesion and aggregation
  • clotting - coagulation phase

  
• describe platelet (3)


  •Small, oval, no nucleus

  •2-3µm diameter

  •contain granules (look into why cells have granules)
• is a platelet a cell? (p)

  (p)'Platelets are not true cells, but are in fact cytoplasmic fragments from large cells found in the bone marrow, called megakaryocytes.' - leeds
• (p) what is a megakaryote?


  'A megakaryocyte (from mega- 'large' karyo- 'cell nucleus' and -cyte 'cell') is a large bone marrow cell with a lobated nucleus that produces blood platelets (thrombocytes), which are necessary for normal clotting.' - wiki

  '(it is a precursor cell (in cell biology, precursor cells—also called blast cells—are partially differentiated, or intermediate, and are sometimes referred to as progenitor cells. A precursor cell is a stem cell with the capacity to differentiate into only one cell type, meaning they are unipotent stem cells))'
• (p)where are platelets found?


  theyre found in bone marrow, and ' bud from megakaryotes'
• life span of platelets? how many functions do they have and what process are they vital for?


  •Normal lifespan 7-10 days

  •Variety of functions essential to thenormal process of haemostasis
• what are platelets? (based on slide) what's their production controlled by?


  Megakaryocyte cytoplasm

  • Production controlled by: no. of circulating platelets (negative feedback),
  • thrombopoietin (TPO) release (increase platelet numbers)

  
• after vessel injury, what kickstarts the following: platelet adhesion, blood coagulation phase

  what else happens after vessel injury that wasn't mentioned?

  collagen exposure -> platelet adhesion

  tissue factor -> blood cascade

  vasoconstriction also happens after vessel injury (minimises blood loss?)
• see if you can fill this flow chart after vasoconstriction, platelet adhesion and blood tissue cascade


  image

  
• card that demonstrates blood clotting visually:

  
• what happens to fibrinogen in the Coagulation phase?


  Fibrinogen is a soluble protein in the blood that gets converted by an enzyme called thrombin, through polymerisation it turns into the insoluble protein fibrin which gets stabilised by factor XIII.

  
• extra context (p) diff between fibrin and fibrinogen? what does fibrinogen do


  extra (p) context: ' The main difference between fibrin and fibrinogen is that fibrin is a thread of proteins that forms the mesh during the formation of blood clot whereas fibrinogen is a plasma protein involved in the formation of fibrin'

  
  

  'Fibrinogen is a protein produced in the liver. It helps create blood clots, heal wounds, and grow new blood vessels in response to injury, infection, or inflammation.'
• what are the three pathways in haemostasis?


  extrinsic pathway, intrinsic pathway and common pathway