Haematology Flashcards
What is the average lifespan of neutrophils?
2-4 days
Where is bone marrow predominantly found in adults?
pelvis, sternum, skull, ribs and vertebrae
In which places are we more likely to get cancer?
Places where the bone marrow is more active
Approximately how much of bone marrow should be adipocytes?
50%
Where do cells attach as they mature?
The stroma of the bone marrow
What is haemopoiesis?
The formation of blood cellular components
Which hormone drives RBC formation?
Erythropoietin
Which hormone drives platelet production?
Thrombopoietin
What is the origin of all blood cells?
Haemocytoblast (haematopoietic stem cell)
What 2 types of progenitor cells are derived from the haemocytoblast?
myeloid progenitor and lymphoid progenitor
Which cells are of the lymphoid lineage?
NK cells, B and T lymphocytes and plasma cells
What are the functions of RBCs?
carry haemoglobin and deliver oxygen to tissues, maintain haemoglobin in reduced form, maintain osmotic equilibrium and generate energy
Which state of haemoglobin is the binding state?
R state
What are the roles of globin chains?
protect haem molecule, confer solubility and permit variation in oxygen affinity
Where are the gene clusters for haemoglobin?
Chromosomes 11 and 16
When do we switch from fetal to adult haemoglobin?
3-6 months
What are the steps of erythropoiesis?
reduced partial pressure of oxygen detected in kidneys (hypoxia) : interstitial peritubular cells, increases production of erythropoietin, stimulates maturation and release of RBCs from bone marrow : acts on E-progenitor cells of bone marrow, haemoglobin conc rises, partial pressure of oxygen rises, erythropoietin production falls
Which cells does erythropoietin act on?
E-progenitor cells in the bone marrow
Which cells produce platelets?
Megakaryocytes
Where are platelets stored until needed?
Spleen
What are the functions of platelets?
- adhere to connective tissue
- aggregate with other platelets
- form platelet plugs
- facilitate clotting
Name some structural features of platelets and why they are important
Phospholipid membrane = for clotting factor and platelet adhesion
Alpha granules = contain glycoproteins to make receptors
Dense bodies = contain molecules to aid platelet aggregation
Which molecules aid platelet aggregation?
serotonin, ADP, catecholamines and calcium
Which receptor can platelets adhere to?
vWF receptor
Von Willebrand factor
What is the function of a fibrin mesh?
trapping platelets and RBCs
What is the reticuloendothelial system?
cells identify and mount an appropriate immune response to foreign antigens and the recycling of nutrients and amino acids occurs
What colour granules do eosinophils have?
Orange/red
How long are eosinophils in circulation and what is their lifespan?
3-8 hours in circulation
8-12 day lifespan
What are the roles of eosinophils?
phagocytosis of antigen-antibody complexes and mediation of hypersensitivity reactions (asthma, skin inflammation)
What is the half-life of basophils?
2.5 days
What do the dense granules of basophils contain?
histamine, heparin, hyaluronic acid and serotonin
Which cells form antibodies?
B lymphocytes
What are the 2 types of T lymphocytes?
Helper cells (CD4+) Suppressor cells (CD8+)
What can B cells transform into?
plasmablasts or memory cells
What do plasmablasts do?
produce lots of antibodies and migrate to marrow to form plasma cells
How do T cells differentiate?
migrate to thymus and undergo TCR rearrangement before differentiation
What is the role of CD4+ cells?
induce proliferation and differentiation in T and B cells and activate macrophages
What are CD8+ cells for?
Cytotoxic activity to induce apoptosis in other cells
Which cells stop the formation of tumours?
NK cells
How do NK cells kill?
By lysis (same mechanism as T cells)
What is the average life span of a platelet?
10 days