STRUCTURE OF ERYTHROCYTES.pptx By Dr.Farhan Abid Rana

ppt about rbcs

1. “ STRUCTURE OF ERYTHROCYTES” Presenter DR.FARHAN ABID RANA PGD FMU 2024-2026

2. ERYTHROCYTES Erythrocytes  (red blood cells or RBCs) are anucleate , biconcave  cells , filled with hemoglobin, that transport oxygen and carbon dioxide between the  lungs  and  tissues . They are produced in the  red bone marrow  by a process called erythropoiesis.  These mature RBCs are released into the bloodstream, where they survive between 100 to 120 days.

3. FEATURES Erythrocytes have a consistent diameter of 7-8 µm. E rythrocytes have a biconcave shape, which resembles a donut. E rythrocytes do not have a  nucleus  ( anuclear ) or any other intracellular  organelles . Only two major structures left are the cytoplasm which is enclosed by a surrounding cell membrane CYTOPLASM- contains the hemoglobin CELL MEMBRANE- lipid bilayer containing peripheral and integral proteins

4. Hemoglobin Hemoglobin is a complex iron-containing protein found in erythrocytes (red blood cells) of most vertebrates that plays a vital role in carrying oxygen and carbon dioxide within the blood. . Beside RBC, hemoglobin is also present in alveolar cells,  macrophages , some neurons of the midbrain, mesangial cells of kidneys, hepatocytes, vaginal epithelial and cervical cells, etc . Hemoglobin is synthesized together with the red blood cells (RBCs) during erythropoiesis in the bone marrow. The iron part ( heme part) is synthesized in the  cytoplasm  and  mitochondria  of developing RBC and the protein part (globin protein) is synthesized by the ribosome of the growing RBC Oxygen + Hemoglobin = Oxyhemoglobin 98% Carbondioxide + hemoglobin = Carbaminohemoglobin 2-3%

5. ALLOSTERY Hgb is a globular metalloprotein with a quaternary structure . One hemoglobin molecule is composed of four subunits; each containing one  polypeptide chain  (chain of globin protein) attached with a prosthetic  heme group The polypeptide chains in adults are of two types, the alpha chain and the beta chain containing 141 and 146  amino acids  respectively.  Adult hemoglobin has  two alpha subunits  (α1 and α2) and  two beta subunits  (β1 and β2 )  Each subunit has a heme attached to the globin protein In fetal hemoglobin, the beta subunits are replaced by  gamma subunits  (γ1 and γ2 ). The heme group contains an iron ( ferrous ion, Fe +2 ) held in the center of a  porphyrin ring  binding with the nitrogen atoms of the ring. The Fe +2  ion is bound to the pocket of the globin subunit with a histidine residue. Each Fe +2  ion can bind with one oxygen (O 2 ) molecule or one carbon dioxide (CO 2 ) molecule