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23 Cards in this Set

  • Front
  • Back
where can congenital anemias attack the RBC?
in membrane, Hb or enzymes
two most common enzymatic hemolytic anemias?
pyruvate kinase deficiency and G6PD def
subunits of Hb? Mb?
2 alphas and 2 Betas. One glogular protein
how many hemes in each Hb?
4, one for each subunit
describe the importance of the two valences of iron in heme.
one binds the cavity of the Hb subunit and the other binds O2
why is the binding of O2 to Hb sigmoidal?
the hemes are cooperative in that when one binds an O2, the others are more apt to bind O2
describe the Bohr effect. (look this up)
increased CO2 causes decrease in the pH of the blood and therefore Hb does not bind O2 as tightly as before. 2,3 BPG also facilitates O2 disociation so O2 will go to the tissues
breakdown product of heme?
energy source for RBCs and why?
glucose only bc there are no mitochondria
describe iron deficiency anemia.
inadequate intake or excessive loss of iron
describe methemoglobinemia
iron in the center of the heme becomes oxidized. Can be acquired via ingestion of chemicals or inherited via a genetic deficiency in MHb reductase.
describe thalassemia
mutations of alpha or beta globins resulting in decreased production or complete absence of one of the globin chains, note can occur in exon or non coding region (causes a reduction in the quantity of one or the other of the major globin chains
describe megaloblastic anemias
decreased absorption or dietary deficiency of folic acid, vit B12 or both
describe hereditary spherocytosis
defects/deficiencies of RBC membrane associated cytoskeletal proteins
describe structurl heminglobinopathies
sequence changes in globin genes
inheritance of G6PD def?
X linked
why does anemia often accompany late stage renal phase?
erythropoietin is produced by renal peritubular cells in response to kidney O2 levels. EPO is the most important groth factor regulating erythropoeisis
describe the genetics of Hb and how it changes throughout life.
HbA is the adult form of a2B2. other globulins are zeta which is alpha like and epsilon, gamma, and delta which are alll beta like. Chromosomes 11 and 16 have the genes (note two genes for alpha and two for gamma). Hb gower (Z2E2) is the embryonic form for the first 8 to 10 weeks. HbF (A2G2) is the fetal form. HbA2 (A2D2) is a minor Hb present throughout adult life (2 to 5% of total Hb). note in some forms of thalassemia, HbF and HbA2 levels may be elevated
describe the proteins unique to the RBC membrane. Lipid organization?
integral ones include glygophorins, Bands (an anion transporter). Membrane associated ones are spectrkins and ankryns which are very important in anchoring proteins in the bilayer. Others include actin, tropomyosin, band 4.1, adducin and tropomodulin. outer lipids include cholesterol, phos choline, sphingomyelin while the inner leaf includes chol, phos serine, phos ethanolamine
describe the protein malfunctions in hereditary spherocytosis and hereditary elliptocytosis.
microcytic hemolytic anemias which results from congenital deficiencies in the function or quantity of one of the membrane associated proteins, usually spectrin or ankyrin. RBCs are small, spherical and have fragile membranes. Cells are small bc membrane lipid is lost by vesiculation during circulation. these small and fragile spherocytes have shorter life due to removal by the spleen
describe the major RBC metabolic pathways. describe how G6PD def leads to anemia. Pyruvate kinase?
glycolysis is the major source of ATP. ATP is used for membrane pumps regulating cellular ion content and hydration. Hexose monophosphate shunt provides NADPH needed to maintain glutathione in a reduced state. GSH (reduced glutathione) is needed to eliminate reactive oxygen species from the oxidative environment of the RBC interior. Note that NADH is used to reduce MetHb back to Hb
important stuff
cooperativity, difference bw oxygenation and oxidation, methhemoglobin reductase, no mitochondria thus glucose only used, bohr effect, congenital hemolytic anemais, G6PD is more common in african americans and meditteraneans
describe how G6PD def leads to anemia. Pyruvate kinase?
most common enzymopathy, 10% of ppl WW, seen where malaria is seen (likes AA's and meditteraneans), most are asympto, but can have anemic episodes if exposed to certain drugs, infections, or if they eat fava beans or foods high in nitrite preservatives. GSH is depleted from this mutation bc of insuficient NADPH (G6PD fxns in reducing NADP+). thus oxidative damage to RBC membranes and Hb denaturation. severity depends on extent of enzymatic def and enzymatic stability in the RBC. more unstable types get more episodes resulting in serious anemia and jaundice. pyruvate kinase def is most commonly occuring congenital DO of the glycolytic pathway. resulting ATP def in RBCs lead to abnormal Na, K, Ca, and water homeostasis and a chronic nonspherocytic hemolytic anemia. RBCs are more susceptible to lysis or retention and destruction in the spleen. In blood smears they have polikocytosis and xerocytosis (cellular dehydration)