1 / 19

MLAB 1415- Hematology Keri Brophy-Martinez

MLAB 1415- Hematology Keri Brophy-Martinez. Chapter 6: Hemoglobin. Hemoglobin. What is it? Iron- bearing protein which is the main component of the RBC Gives the red cell its color Synthesis Majority synthesized at the polychromatophilic normoblast stage Regulation

dayton
Download Presentation

MLAB 1415- Hematology Keri Brophy-Martinez

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MLAB 1415- HematologyKeri Brophy-Martinez Chapter 6: Hemoglobin

  2. Hemoglobin • What is it? • Iron- bearing protein which is the main component of the RBC • Gives the red cell its color • Synthesis • Majority synthesized at the polychromatophilic normoblast stage • Regulation • Stimulated by tissue hypoxia • Hypoxia causes the kidneys to increase production of EPO, which increases RBC and hemoglobin production • Function • Carry oxygen from the lungs to the tissues • Remove CO2 • Buffering action, maintains blood pH as it changes from oxyhemoglobin (carrying O2) to deoxyhemoglobin ( without O2)

  3. Hemoglobin Reference Ranges • Adults • Male 14-17.4 g/dL • Female12-16.0 g/dL • Children • Birth 13.5-20.0 g/mL • 6-12 years 11.5-15.5 g/mL **Refer to inside cover of text for other age ranges

  4. Structure • 4 polypeptide Subunits • Heme group • Porphyrin ring • Ferrous iron • Globin chain • 2 Alpha Chains • 2 Beta chains

  5. Hemoglobin Synthesis • Synthesis • Occurs in the mitochondria of developing red cells as they mature in the bone marrow • Processes necessary for normal synthesis • Adequate iron supply & delivery • Adequate synthesis of protoporphyrins • Adequate globin synthesis

  6. Heme Synthesis • Chain of Events • Iron delivery & supply • Iron is delivered to the reticulocyte by transferrin • Synthesis of protoporphyrins • Occurs in the mitochondria of RBC precursors • Mediated by EPO and vitamin B6 • Protoporphyrin + iron = heme

  7. Globin Synthesis • Chain of Events • The rate of globin synthesis is proportional to the rate of porphyrin synthesis. • Proper globin synthesis depends on genes. The precise order of amino acids in the globin chains is critical to the structure and function of hemoglobin. • Chain designations are as follows • Alpha α, beta β, delta δ, epsilon ε, gamma γ, zetaζ

  8. Normal hemoglobins

  9. Hemoglobin Synthesis

  10. Oxygen transport • The amount of O2 bound to hemoglobin and released to tissues depends on PO2 and PCO2, but also the affinity of hemoglobin for O2. • Oxyhemoglobin: hemoglobin with oxygen • Deoxyhemoglobin: hemoglobin without oxygen • Oxygen affinity is the ease with which hemoglobin binds and releases oxygen.

  11. Oxygen Affinity • Determines the proportion of O2 released to the tissues or loaded onto the cell at a given oxygen pressure. • Increases in oxygen affinity means hemoglobin has an increased affinity for O2, so it binds more. However, it does not want to give it up. • Decreases in oxygen affinity, cause O2 to be released.

  12. Bohr Effect • Alterations in blood pH, shifts oxygen dissociation curve • In acidic pH, the curve shifts to the right • Results in an enhanced capacity to release O2 where it is needed

  13. Oxygen Dissociation Curve • Right-Shift • Hgb has less attraction for O2 • Hgb willing to release O2 to tissue • Examples: anemia, acidosis • Even though there may be less RBC’s, they act more efficiently to deliver O2 to target

  14. Oxygen Dissociation Curve • Left shift • Hgb has more attraction for O2 • Hgb less willing to release O2 to tissue • Examples: presence of abnormal Hgb’s, alkalosis

  15. Carbon Dioxide Transport • Three mechanisms of transport • Dissolution in the plasma • Formation of bicarbonic acid • Binding to carbaminohemoglobin

  16. Nonfunctional hemoglobins • What do they do? • Hypoxia • Inadequate amount of O2 in the blood • Cyanosis • Presence of > 5 g/dl deoxyhemoglobin in blood • Patient appears blue

  17. Nonfunctional hemoglobins • Carboxyhemoglobin • Oxygen molecules bound to heme are replaced by carbon monoxide. • Slightly increased levels of carboxyhemoglobin are present in heavy smokers and as a result of environmental pollution. • Can revert to oxyhemoglobin. • Methemoglobin • Iron in the hemoglobin molecule is in the ferric (Fe3) state instead of the ferrous (Fe2) state. Incapable of combining with oxygen. • Can occur as a result of strong oxidative drugs or to an enzyme deficiency (more discussion to follow). • Can revert to oxyhemoglobin • Sulfhemoglobin • Hemoglobin molecule contains sulfur. • Caused by certain sulfur-containing drugs or chronic constipation. • Cannot revert to oxyhemoglobin and may cause death.

  18. References • McKenzie, S. B. (2010). Clinical Laboratory Hematology (2nd ed.). Upper Saddle River, NJ: Pearson Education, Inc..

More Related