Red Cell Physiology Flashcards
Erythropoiesis
The process of forming new red blood cells
Erythropoietin
(EPO)
polypeptide hormone
Released by peritubular cells in kidney as response to hypoxia, e.g.
- Anaemia
- Altitude
- COPD
Increases number of stem cells committed to erythropoiesis
Why might recombinant EPO be used clinically
Treating anaemias associated with renal failure
EPO is released by the kidney
Reticulocytes and what elevated levels indicate
Immature RBC; nucleus extruded and taken up by bone marrow macrophages
Has some dollops of mRNA as cell is still developing
Elevated reticulocyte counts indicates ongoing erythropoeisis
- bleeding
- haemolysis
Average RBC Life Span
120 Days
How is RBC lifespan measured (vaguely)
Blood sample is taken out and radioactively labelled then injected back; measure rate at which it takes radioactivity decreases at body (should be 120)
HbA1c
Glycated/Glycosylated Haemoglobin
Spleen in spherocytosis
Genetic Condition;
Abnormal proteins in RBC (spectrin) that breaks down more rapidly
Degradation of RBCs - Where does it occur and what happens to the proteins
Occurs in reticuloendothelial system (mononuclear-phagocyte system) of spleen, liver + bone marrow
Proteins degraded and recycled;
- iron in stores
- porphyrin (from haem) converted to bilirubin in liver
Bilirubin; what might elevated levels indicate
Yellowish pigment that is made during the normal breakdown of red blood cells
Elevated levels indicate liver disease or elevated RBC breakdown
**Bilirubin causes jaundice
Components of Hb
Ferrous Iron (Fe2+) prosthetic groups [Haem] 2 alpha, 2 beta globin polypeptides linked via non-covalent bonds
Haem at centre of protoporphyrin complex
Foetal Hb vs Adult Hb
Foetuses have Hb containing a2γ2 vs adult which has a2b2
Theres a significant switch at the early part of birth where the foetal Hb is replaced
Best form of iron to get from the diet
Fe2+
This is why eating meat doesn’t necessarily give high iron levels (Fe3+)
Iron from diet; drug interaction
Some drugs (like tetracycline) can cause chelation of iron and prevent its uptake (antacids have a similar effect)
How does iron from diet metabolise
Fe3+ from diet reduced to Fe2+ by syomach acid/is taken up as Fe2+ in the first place
Fe2+ is then converted to Fe3+ in the duodenal cells because god knows why
It is then made into ferritin
Iron is delivered to bone marrow by transferring and stored as ferritin
Incorporated as Hb