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The Red Blood Cells Introduction

The Red Blood Cells Introduction. The Red Blood Cells. The red cells are not true cells in the strict sense. They contain no nucleic acids, and cannot reproduce. They contain no cell organelles and possess no synthetic activities. Composition of the RBCs.

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The Red Blood Cells Introduction

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  1. The Red Blood Cells Introduction

  2. The Red Blood Cells • The red cells are not true cells in the strict sense. • They contain no nucleic acids, and cannot reproduce. • They contain no cell organelles and possess no synthetic activities

  3. Composition of the RBCs • Red cells contain 35 % solids, mainly Hb • Hemoglobin, the chief protein of the red cells. • Other proteins are present in combination with lipids and oligosaccharide chains, forming the stroma and cell membrane. • Potassium, magnesium, and zinc concentrations in red cells are much higher than in the plasma.

  4. Metabolism • Erythrocytes contain no mitochondria, so there is no respiratory chain, no citric acid cycle, and no oxidation of fatty acids or ketone bodies. • Energy is obtained from the glycolytic breakdown of glucose with the production of lactate. • ATP produced being used for the Na+ pump.

  5. Metabolism contd. • Rapoport and Luebering described a special enzymatic side-pathway in glycolysis. • Bisphosphoglycerate mutase converts 1,3- bisphosphoglycerate(1,3-BPG) to 2,3- bisphosphoglycerate(2,3-BPG). • This reaction wastes the high- energy bond in 1,3- BPG without generation of ATP. • This explain the fact that the red blood cells utilize more glucose than is required to maintain their vitality

  6. Metabolism contd. • The red cells contain an active pentose phosphate pathway that supplies NADPH • NADPH is important in keeping glutathione in the reduced glutathione. • Reduced glutathione plays a very important role in the survival of the red blood cells. • Deficiency of glucose 6- phosphate dehydrogenase leads to reduced red cell survival

  7. Metabolism contd. • The erythrocytes contain carbonic anhydrase. carbon dioxide combines with water only after it enters the red cells where hemoglobin, the most important buffer for the resulting carbonic acid, is present. • The red cell also contain rhodanese enzyme responsible for the detoxication of cyanides.

  8. Red Cell Membrane Structure • RBCs must be able to squeeze through some tight spots in microcirculation. • 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 comprise a lipid bilayer( which determine the membrane fluidity), proteins ( which is responsible for flexibility ) are either peripheral or integral penetrating the lipid bilayer. • Carbohydrates occur only on the external surface. • The major lipid classes are phospholipids & cholesterol. Glycoshingolipids as gangliosides including ABO blood group substances constitute 5-10% of the total lipids.

  9. Examples of changes occurring in aging red cells: Red Cell Aging

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