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Heme Lec 10
MLS Heme Lec 10
| 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 |
Created by:
mlrlemons
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