L12&13 - Blood & Body Fluids Flashcards
outline the phases of red cell production in the bone marrow
Haemocytoblast (stem cell)
→ proerythroblast
stimulated by erythropoietin
→ erythroblast
→ normoblast
nucleus expelled
→ reticulocyte
→ erythrocyte (released into blood)
what happens when the kidneys detect low oxygen levels?
erythropoietin is secreted into the blood which increases mitotic rate and accelerates cell maturation
this means proerythroblasts mature into reticulocytes rapidly and enter the blood stream
larger number of RBCs in blood means increased oxygen delivery to tissues
return to homeostasis
what do normal RBCs look like?
biconcave, non-nucleated, approx. same diameter as capillaries
what nutrients are required for red cell production in the bone marrow?
- adequate nutrition
- protein
- vitamins e.g. folic acid
- hormone - erythropoietin
what are reticulocytes?
fully matured RBCs that are released into the blood
what is the function of RBCs?
transportation of oxygen and carbon dioxide
blood buffer - maintains pH 7.4
what is the structure of a normal haemoglobin molecule?
4 polypeptide chains each linked to one Haem molecule, each haem contains one iron atom to which O2 associates
what 2 factors contribute to the generation of the oxyhaemoglobin curve?
oxygen partial pressure and haemoglobin saturation
what is the significance of the plateau on the oxyhaemoglobin curve?
the ‘plateau’ portion of the oxyhaemoglobin dissociation curve is the range that exists at the pulmonary capillaries (minimal reduction of oxygen transported until the PO2 falls below 60mmHg
describe the breakdown of RBCs
- 120day lifespan (trapped in spleen)
- haem separates from globin, globin recycled as amino acids
- haem breakdown yields iron (recycled)
- other haem breakdown products yield biliverdin and bilirubin (taken to liver and secreted in bile)
what is sickle cell disease?
genetic disorder, symptoms in children
what is sickle cell disease?
genetic disorder, symptoms in children
what is sickle cell haemolytic anaemia?
sickled cells are fragile - need for transfusions +++
cells become trapped in microcirculation - obstruct blood flow - ischaemia & severe pain, stroke, jaundice, resp symptoms
what is the basis for major blood group classifications?
determined by the antigen present on red cell membrane
why is group O negative the universal?
no antigens present - no reaction with patients plasma
