Question | Answer |
Hemoglobin consist of | 4 globin protein chains containing a heme component nestled in a hydrophobic crevice |
Heme is what shape | tetrapyrrole ring with ferrous iron in the center |
Heme carries how many oxygen | 1 |
Hemoglobin can carry how many oxygen | 4 |
65% of hemoglobin synthesis occurs | during the nucleated stages of RBC maturation |
35% of hemoglobin synthesis occurs | during the reticulocyte stage |
Heme | 4 groups each one contains a protoporphyrin ring plus ferrous iron |
Globin | tetramer of two pairs of unlike globin polypeptide chains |
Normal production depends on | 1. iron delivery and supply
2. synthesis of protoporphyris (heme precursor)
3. globin synthesis |
Large hemoglobin molecules give RBCs | color and most of the cell weight |
Hemoglobin's most important function | oxygen and carbon dioxide transport |
What 3 elements must be present to make hemoglobin | globin chains
heme molecule
iron |
Hypochromic and Microcytic cells are formed because | the hemoglobin is defective |
Thalassemia | defective globin chains |
Iron deficiency anemia | lack of iron (most common) |
Sideroblastic anemia | lack of heme |
How much of the body's iron is bound to heme | 2/3 |
How much iron is needed daily | 1mg of iron for each mL of RBCs, 20-25 daily |
How much iron is present as tissue iron | 1/3 |
How much iron is in storage | 90% ferritin, hemosiderin |
How much iron is unavailable | 10% myoglobin, cytochrome enzymes |
Total body iron content of an adult | 3500mg |
Normal Iron Metabolism | body iron is repeatedly recycled
tightly regulated process
daily intake, absorption, & losses are very small |
Life span of RBC | 120 days |
Healthy adult blood volume | 4500-5000mL |
2mL blood contains how much iron | 1mg |
How much blood is lost to senescence daily | 37-42mL |
How many mg of iron is needed each day to replace the iron lost to senescent RBCs | 18.5-21mg |
Iron from RBC turnover is reutilized via | the mononuclear phagocytic system |
Of the 15mg intake of iron per day how much is absorbed | 5-10% |
To make up for iron deficiency food has been | fortified with iron |
Foods highest in iron | organ meats
wheat germ
brewer's yeast
legumes |
Foods moderate in iron | muscle meats
fish
fowl
prunes
cereals
some green vegetables |
Compounds that increase absorption of iron | fructose
amino acids
ascorbic acid (vitamin C) |
Compounds that decrease absorption of iron | phosphates (antacids)
milk |
Factors which affect daily iron requirements | growth spurts
menstruation
pregnancy
lactation and breast feeding
iron deficiency |
Women and children are most prone to | increased dietary needs (IDA) |
Iron is absorbed in the | duodenum of the jejunum |
Most common dietary form of iron | ferric (Fe+3) |
Ferric iron is converted into the ferrous (Fe+2) by | acid in the stomach |
Ferrous iron enters the mucosal cells of the intestine where it is | Converted back to ferric iron
Complexes with apoferritin to form transferrin |
Heme iron is also present as | myoglobin and hemoglobin |
Myoglobin and hemoglobin (iron in dietary meat) | is more readily absorbed by mucosal cells
absorbed as intact heme molecules
iron is free and utilized |
Tranferrin (protein carrier) | delivers ferric iron to RBC precursor |
Where is ferric iron (Fe+3) is changed to ferrous iron (Fe+2) | mitochondria |
How does transferrin transport ferric iron | crosses cell membrane
enters the cytoplasm
goes to mitochondria
delivers ferric iron |
The delivered iron will be incorporated into | hemoglobin |
Amount of ferrtin depends on the amount of | iron needed to make hemeoglobin |
Ferritin | storage form of iron |
Why must iron have a hydrophobic pocket | it must be prevented from oxidizing |
Heme synthesis begins where and what does it do | mitochondria with the formation of protoporphyrin synthesis |
Protoporphyrin synthesis | Glycine ALA + Succinyl Coenzyme A = delta-aminolevulinic acid |
Enzymatic steps are influenced by | erythropoietin
vitamen B6 |
Heme synthesis I | ALA->PGB->URO->Cop->Pro+Fe = heme |
Each enzyme step yields unstable substances called | porphyrinogens |
Porphyrinogens change into | oxidized to a more stable substance called porphyrins |
Conversion of protorphyrin IX, iron is incorperated to yield | heme |
Heme synthesis II | Glycine ALA + Succinyl CoA->->-> Protoporphryn IX/ring + Ferrochelatase -> Heme |
Popyrias | metabolic disorders
Test for genetic deficiencies in enzymes
Accumulate in bone marrow, brain, & liver |
Cause of excess porphyria | blockage of any enzymatic pathway |
Impaired protpporphoryn synthesis causes | iron accumulation in the cytoplasm as ferritin aggregates |
Sideroblast | iron-laden, nucleated RBC |
Siderocytes | non-nucleated form |
Ringed Sideroblast | mitochondria become encrusted with iron and is visible around the nucleus of the RBC precursor |
What stain must be used to view iron in a cell | prussian blue |