Red Blood cells Flashcards
Where do blood cells originate
bone marrow
What are blood cells derived from
haemopoietic stem cells (HSC)
Why are HSC described as “self-renewing”
some daughter cells remain as HSCs so the pool is not depleted
What are the sites of haemopoiesis in foetus
Yolk sac (1-3wks) Liver (4-8wks) Bone marrow (8-adulthood)
Where are progenitor and HSC distributed
Within the bone marrow amongst mesenchymal cells, endothelial cells and the vasculature
What is haemopoiesis regulated by
genes, transcription factors, growth factors and the microenvironment
What happens if haemopoiesis is not regulated
disturb balance between proliferation and differentiation
What are irons main functions
oxygen transport in haemoglobin and mitochondrial proteins
What does erythrocyte function depend on
Integrity of membrane, haemoglobin structure and function and cellular metabolism
What is the red cell membrane made up of
made up of lipid bilayer supported by protein cytoskeleton and contains transmembrane proteins
Why is the red cell membrane important
maintains the integrity, shape and elasticity of red cell
What does disruption in the vertical links of red cell membrane cause
Hereditary spherocytosis
What are spherocytes
cells that are spherical in shape and lack central pallor
What causes spherocytes
loss of cell membrane without the loss of an equivalent amount of cytoplasm. This makes them less flexible and removed prematurely by the spleen (haemolysis)
What does disruption in the horizontal links of red cell membrane cause
Hereditary elliptocytosis
What is glucose-6-phosphate dehydrogenase
Important enzyme in the hexose monophosphate shunt which is couple to the Glutathione metabolism which protect red cells from oxidant damage
What is 2,3-diphosphoglycerate and what does it do
allosteric effector produced by the Rapaport-Luebering shuttle. It binds to beta-globin chains in haemoglobin
What are the effects of G6DP deficiency
Intravascular haemolysis associated with irregularly contracted cells
What do irregularly contracted cells look like
Irregular in outline, smaller and lack central pallor. Contain denatured haemoglobin forming round inclusions called Heinz bodies
What are the causes of mircocytosis
Defect in haem synthesis (iron deficiency). Defect in global synthesis called thalassaemia
Types of macrocytosis
round, oval and polychromatic (young and immature)
Causes of macrocytosis
Lack of vitamin B12 or folic acid, liver disease, haemolysis or pregnancy
What is increased number of reticulocytes called
Reticulocytosis
Why might reticulocytosis occur
response to bleeding or red cell destruction (body can’t keep up so produced immature cells)
