1 / 20

BLOOD CELLS METABOLISM

BLOOD CELLS METABOLISM. Objectives of the Lecture. 1- Understanding the general structural & functional features of red blood cells (RBCs). 2- Recognizing the main metabolic pathways occurring in RBCs with reference to their relations to functions of RBCs.

kuame-chapman
Télécharger la présentation

BLOOD CELLS METABOLISM

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. BLOOD CELLS METABOLISM

  2. Objectives of the Lecture 1- Understanding the general structural & functional features of red blood cells (RBCs). 2- Recognizing the main metabolic pathways occurring in RBCs with reference to their relations to functions of RBCs. 3- Identifying some of the main & common diseases of RBCs as implication of defects of RBCs metabolism. 4- Understanding the relation of characteristic features of structure of membrane of RBCs. 5-Recognizing the main functions of other blood cells and their metabolism

  3. RBCs Metabolism & Functions Introduction: • RBCs contain nomitochondria, so there is norespiratory chain, nocitric acid cycle, and nooxidation of fatty acids or ketone bodies. • Energy in the form of ATP is obtained ONLYfrom the glycolytic breakdown of glucose with the production of lactate (anaerobic glycolysis). • ATP produced being used for keeping the biconcave shape of RBCs & in the regulation of transport of ions & water in and out of RBCs.

  4. Red Blood Cells(erythrocytes) • Function erythrocyte as a bag forhemoglobin • O2→ transport, reactive oxygen species (ROS) • CO2→ transport, formation of HCO3- • H+→ transport, maintaining pH(35% of blood buffering capacity) • Structure • large surface(for diffusion of gases) • cytoskeletal proteins (for elasticity) • membrane as an osmometer(Na+/K+-ATPase)

  5. RBCs membrane structure • RBCs must be able to squeeze through tight spots in microcirculation (capillaries). For that RBCs must be easily & reversibly deformable. Its membrane must be both fluid & flexible . • About 50% of membrane is protein, 40% is fat & up to 10% is carbohydrate. • RBCs membrane comprises a lipid bilayer (which determine the membrane fluidity), proteins(which is responsible for flexibility) that are either peripheral or integral penetrating the lipid bilayer & carbohydrates that occur only on the external surface. • Defects of proteins may explain some of the abnormalities of shape of RBCs membrane as hereditary spherocytosis & elliptocytosis.

  6. The membrane skeleton is four structural proteins that include  &  spectrin, ankyrin, protein 4.1 & actin • Spectrinis major protein of the cytoskeleton & its two chains ( & ) are aligned in an antiparallel manner .  &  chains are loosely interconnected forming a dimer, one dimer interact with another, forming a head to head tetramer. • Ankyrinbinds spectrin& in turn binds tightly to band 3 securing attachment of spectrin to membrane. • band 3is anion exchange protein permits exchanges of Cl- for HCO3+. • Actin binds to the tail of spectrin& to protein 4.1which in turn binds to integral proteins, glycophorins A, B & C. • GlycophorinsA,B,C are transmembrane glycoproteins

  7. What happens to red blood cells when placed in hypotonic, hypertonic, and isotonic solutions? • acanthocytes • hemolysis • osmolarity(0.9%NaCl)

  8. Red Blood Cells(erythrocytes) • membrane transporters • Na+/K+-ATPase (active transport) • GLUT-1 (insulin independent) • anion exchanger = band 3 protein (Cl-/HCO3-) • membrane antigens • blood groups: ABO system Differ in antigen (glycoprotein) Over the surface of RBCs

  9. Red Blood Cells(erythrocytes) • metabolism • glucose is the main fuel • 90% anaerobic glycolysis(ATP, lactate: Cori cycle; 2,3-BPG) • 10% hexose monophosphate pathway(NADPH) • enzyme defects : * glucose-6-P dehydrogenase * pyruvate kinase→ hemolytic anemia ??? • ATP is generated by anaerobic glycolysis→ ATP is used for ion transport across the cell membrane • glycolysis produces 2,3-BPGand lactate • approx. 5 to 10% of Glc is metabolized by hexose monophosphate pathway → production of NADPH → it is used to maintain glutathione in the reduced state

  10. Red Blood Cells(erythrocytes) 6. Enzymes • carbonate dehydratase (= carbonic anhydrase, CA) CO2 + H2O  HCO3- + H+ • The red cell also contain rhodanaseresponsible for the detoxication of cyanides. • methemoglobin reductase • superoxide dismutase • catalase antioxidative enzyme system • glutathione peroxidase • glutathione reductase

  11. Red Blood Cells(erythrocytes) • Erythropioesis

  12. White Blood Cells(leukocytes) Classification • granulocytes • neutrophils (phagocytosis) • eosinophils (allergy, parasites) • basophils (allergy) • agranulocytes • monocytes→ macrophages • lymphocytes (B, T)→ immunity Reactive oxygen ROS and nitrogen RNS speciesin blood elements ERYTHROCYTES: enzymes for deactivation of ROS formed from high content of oxygen found in the cells PHAGOCYTES:enzymes for production of ROS and RNS to destroy particles in phagosomes

  13. White Blood Cells(leukocytes) Neutrophils (microphages) • high content of lysosomes (hydrolytic enzymes) • few mitochondria • glucosedependent: NADPH production • NADPH is used for production of reactive oxygen species → they kill bacteria

  14. Basofils contain heparin and histamine

  15. B-lymphocytes produce antibodies (= immunoglobulins, -globulins)

  16. Platelets(thrombocytes) participate in hemostasis

  17. Platelets(thrombocytes)

More Related