Flashcards in 19. Haematology Deck (37)
How many red blood cells, platelets and granulocytes are produced every day?
2.5 billion red cells/ kg/ day
2.5 billion platelets/ kg/ day
1.0 billion granulocytes/ kg/ day.
Where are red blood cells, platelets and the majority of white blood cells made?
In the bone marrow.
What does haemopoiesis mean?
Blood cell production.
What is haemopoiesis driven by?
Hormones: erythropoietin (RBC development), thrombopoietin (platelet development), G-CSF, GMCSF and IL-6 (WBC development).
How can giving GMCSF to patients with cancer help?
They will have lowered white blood cell count and GMCSF drives white blood cell production, so will help restore these levels.
What is the difference between monocytes and macrophages?
Monocytes are out of the tissue and then they're classified as macrophages when they move into the tissues.
What should the values of RCC (red cell count), Hb (haemoglobin) and MCV (mean corpscular volume) be?
RCC 4.4-5.9 x 10^12/l
Hb 135-167 g/l
What are the main five functions of the red blood cell?
To deliver oxygen to the tissues, carry haemoglobin, maintain haemoglobin in its reduced/ferrous state, maintain osmotic equilibrium and generate ATP energy.
Why do red blood cells have a biconcave shape?
To make them flexible so they can fit through microcirculation which has a diameter of 3.5um (smaller than the RBC's diameter).
What is the diabetes of a standard red blood cell?
What can mutations to do with the lipid bilayer membrane of RBC cause?
A loss of flexibility so they can't fit through capillaries.
What is the basic configuration of haemoglobin?
A tetramer of 2 pairs of globin chains, each with its own haem group.
What are the two forms of haemoglobin?
Relaxed binding - oxyhaemoglobin.
Tight binding - deoxyhaemoglobin.
What are the functions of haemoglobin?
To carry O2 from the lungs to the tissues and to carry CO2 between the tissues and lungs.
What are the functions of the globin chains in haemoglobin?
To protect the haem molecules from oxidation, confer solubility and permit variation in oxygen affinity by changing shape.
What shape is the oxygen dissociation curve?
How is haemoglobin synthesised?
The globin gene clusters on chromosome 11 and 16. They're synthesised independently and then combines to form different haemoglobins.
When does haemoglobin switch from foetal to adult?
At 3-6 months.
What are the two main metabolic pathways in red cells?
Embden Meyerhof Pathway - glucose metabolised to lactate and ATP is produced.
Hexose monophosphate pathways - glucose-6-phosphate metabolised and NADH is generated.
How is erythropoiesis controlled?
Reduced pO2 is detected in interstitial peritubular cells in the kidney, this triggers increased production of erythropoietin. Maturation and release of RBC from the marrow is stimulated and haemoglobin rises so pO2 also rises. Erythropoietin production falls again.
How are platelets produced?
By megakaryocytes. The cells increase in size and replicate its DNA, the platelets bud off from the cytoplasm.
What is platelet production controlled by?
What are the three main functions of platelets?
Adhesion to connective tissue, aggregation with other platelets and phospholipid membrane to facilitate clotting.
What is the structure of platelets? Consider their membrane, a-granules and dense bodies.
Their membrane is a phospholipid surface for clotting factor and platelet adhesion via glycoprotein receptors.
Their a-granules are glycoproteins.
Their dense bodies include serotonin, ADP, catecholamines and calcium for platelet aggregation.
How is a platelet plug formed?
There is damage to a vessel wall and exposure of underlying tissues. The platelets adhere via vWF/receptor and form a platelet plug.
How do platelets aggregate?
Release of ADP from granules, glycoproteins IIb/IIIa receptors are exposed. There is primary and secondary aggregation.
How does G-CSF control neutrophil maturation?
It increases production of neutrophils, reduces the time to release mature cells from the bone marrow. It enhances chemotaxis and phagocytosis and killing of pathogens.
What is the role of monocytes?
Migrate to tissues - become macrophages. They respond to inflammation and antigenic stimuli by phagocytosis.
What are the three main organs of the reticuloendothelial system?
Spleen, liver and lymph nodes.