RBC metabolism Flashcards
Location of Erythropoietin (EPO) production.
Kidneys
Stimulator of EPO production.
Low O2 levels in the blood signal the Hypoxia Initiation Factor (HIF) 1 to cause transcription of the EPO gene.
EPO regulates blood oxygen levels over a period of days. What regulates blood oxygen delivery to tissues on an hourly basis?
2,3 BPG
-increases in hypoxic states to force Hb to release O2
2 major nutrients required for RBC production.
B12 (needs intrinsic factor for absorption) folic acid (B9)
Why is glycolysis important in RBCs other than energy production?
There are 3 reactions that require glycolysis intermediates to protect the RBC from damage since it has no nucleus or organelles to repair itself.
What are the 3 glycolytic reactions that occur in the RBC to protect it from damage and the function of each?
- Reduced Glutathione: protects from ROS
- Reduced Cytochrome b5: converts Fe3+ (methemoglobin) back to Fe2+ for oxygen binding
- Formation of 2.3 BPG for O2 unloading
What two glycolytic enzyme deficiencies can lead to hemolytic anemia? Also what other hereditary condition also causes hemolysis?
- Glucose-6-Phosphate dehydrogenase
- Pyruvate Kinase
Sickle Cell can also cause hemolytic anemia due to fragile RBCs
Protein that allows iron to be transferred across the cell membrane and into RBCs during heme production.
Transferrin
Main storage protein of iron in the liver.
Ferritin
iron is stored in the Fe3+ state
Name the 3 forms of Hb in adults and the subunit composition.
HbA: 2 alpha 2 beta (main form)
HbA2: 2 alpha 2 delta
HbF: 2 alpha 2 gamma (fetal)
What type of anemia would result from iron deficiency, thalassemias, or lead poisoning?
Microcytic, hypochromic
What type of anemia would result from Vit. B 12 or folic acid def.?
Macrocytic, normochromic
What is Aplastic anemia?
Inability to produce mature blood cells of any lineage because of damaged progenitor cells. Can be caused by drugs, radiation, infection, immune disease, etc.
Cause of Erythroblastalis fetalis.
An Rh- mother has a child that is Rh+ causes antibodies to form against the Rh+ antigen. Then during a second pregnancy, if a child is Rh+, during the birthing the hemolytic reaction occurs in the newborn.
What are the 3 mechanisms that a transfusion reaction (from incorrect blood types) can cause kidney failure?
- Ag-Ab complex formed by the donor blood and host immune system releases toxic substances causing powerful renal vasoconstriction.
- Loss of RBCs, increased toxic substances cause circulatory shock and drop in BP leading to low urine output.
- Hemolysis causes a huge amount of Hb to be released into the blood faster than “haptoglobin” can bind it and the excess Hb agglutinates and blocks the kidney tubules.
(haptoglobin serves to bind free circulating Hb)
