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