Haemopoiesis, Erythropoiesis And Iron Flashcards
Where are blood cells produced
In the bone marrow
Describe the difference in distribution between infanthood and adulthood of bone marrow
Infant: Extensive throughout skeleton
Adult: Predominantly in pelvis, sternum, skull, ribs, vertebrae
Describe the process of haematopoeisis
Multipotential hematopoetic stem cells
Go to Common lymphoid progenitor cells–>Lymphocytes
Also go to Common Myeloid Progenitor–>Megakaryocyte+Granulocyte+Erthyocyte
What system controls and removes blood cells
Reticuloendothelial system
What organ is responsible for the disposal of blood cells
The spleen
What is the membrane of rbcs specialised to do? If damaged, what does it make the rbc
Make rbc flexible
Makes rbc fragile and likely to lyse–>anaemia
What are the three properities that globin chains add to haemoglobin
protect haem group from oxidation, Increase solubility, Permits variation in oxygen affinity
Describe how erythropoiesis is controlled
Reduced pO2–>Increase erthyropoetic hormone (from kidney)–>Increased synthesis of rbcs in the bone marrow–>Increased pO2–>Reduction in production of Erythropoetin
Name the two main metabolic pathways in rbcs
Glycolysis
Pentose Phosphate Pathway
How is iron in the body controlled
By controlling the absorption of iron and the iron released from macrophages. No mechanism for excretion
In which two carriers is iron stored
Ferritin- eg in hepatocytes
Haemosiderin-Macrophage iron
Where is the majority of iron stored.. what about the other 5% of iron?
Majorityin hepatocytes as ferritin
Hemosiderin constitutes the remaining 5% in kupffer cells (macrophages in the liver)
Does haem iron exist as ferrous iron (Fe2+) or ferric iron (Fe3+)?
Ferrous. Non haem exists as ferric iron
Describe th eprocess of how ferric iron is transported into the bloodstream from the gi system
In the stomach Fe3+–>Fe2+
Fe2+ binds to transferrin
Enters epithelial cellls lining the intestine
Either stored in the enterocyte as ferritin or transported into the bloodstream via ferroportin
Then either stored in the liver or used in Hb
How is iron taken into cells
By binding of iron-transferrin complex to transferrin receptor
What two substances aid in the absorbtion of iron?
Ascorbic acid and vit C
What is the name of the central regulator of iron metabolism and how does it work?
Hepcidin
Released by the liver
Synthesis is increased in iron overload
binds to ferroportin and prevents it working
so iron can enter epithelial cells, but remains stored there aas cannot enter the bloodstream
List 6 symptoms if anaemia
tiredness Pallor decreased exercise tolerance cardiac symptoms (eg angina) Tachycardia increased resp rate
Name two tests used to test for iron deficiency
Ferritin( if otherwise well. Acute phase protein so can increase with inflammation
CHR
Suggest treatments for iron deficiency
Dietary advice Oral iron supplements Intramuscular iron injections Intravenous iron Transfusion (only if severely anaemic)
Describe the process of hereditary haemochromatosis (why iron incresses)
Mutations in the HFE gene
HFE normally competes with transferrin for binding to transferrin receptor
Mutated HFE cant bind so transferrin has no competition, so too much iron enters cells from GI system
What chemical stimulayes a- Lymphocyte production b- Megakaryocyte production c- Erythrocyte production d- Granulocyte production
a- ILs and TNFs
b- thrombopoietin
c- Erythropoetin
d- Granulocyte colony stimulating factor
What does the RES consist of?
Phagocytic cells
Give 4 functions of red blood cells
carry Hb
Maintain Hb in a reduced state
generate energy
maintain osmotic equilibrium
How is Haemoglobin catabolised?
Hb–>Haem–>bilirubin
Bilirubin goes to the liver, used for bile
bile absorbed in the colon and excreted in the kidneys
what can increased destruction of red blood cells lead to an why?q
Jaundice
Product of Hb catabolism is bilirubin
Name four sites where available iron is kept
Hb
Myoglobin
tissue iron
transported iron in serum
Two features of the blood film in iron deficiency anaemia?
Hypochromic red blood cells (Decreased Hb in cells)
Microcytic red blood cells
Three causes of iron deficiency?
Decreased uptake Increased loss (Eg Gi problems) Excessive use (pregnancy)
What is haemochromatosis? Complication?
Iron deposition in organs–>organ damage
Liver cirrhosis, diabetes, skin pigmentation, hypogonadism, cardiomyopathy
Two causes of haemochromatosis?
Hereditary or transfusion associated
