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Red blood cells RBC (erythocyte) - Coggle Diagram
Red blood cells RBC (erythocyte)
Hemoglobin and oxygen transport
Haemoglobin (Hb) composition
4 polypeptide chains
Each chain contains a heme group with an iron, ion that binds oxygen.
Oxygen binding and release
High O₂ affinity in lungs
Hb binds oxygen due to high partial pressure
Low O₂ affinity in tissues
Hb releases oxygen where partial pressure is low
Cooperative binding
Each O₂ molecule increases Hb's affinity for more O₂.
Abnormalities in red blood cells
Anemias (reduces RBC or Hb
Iron Deficiency Anemia
Lack of iron reduces Hb synthesis.
Aplastic Anemia
Bone marrow failure reduces RBC production.
Pernicious Anemia
Vitamin B12 deficiency affects DNA synthesis
Polycythemia (Excess RBCs)
Primary polycythemia
Overproduction in bone marrow
Secondary polycythemia
Due to chronic hypoxia
Sickle cell disease
Genetic mutation in the beta-globin gene → HbS formation → RBCs become sickle-shaped → Block blood flow.
Life cycle
Production (Erythropoiesis)
Occurs in red bone marrow, regulated by erythropoietin (EPO) from the kidneys.
Stem cells → Proerythroblast → Erythroblast → Reticulocyte → Mature RBC.
Lifespan
120 days
Destruction:
Old RBCs removed by macrophages in the spleen and liver.
Hemoglobin broken down
Structure
Biconcave shape
Increases surface area for gas exchange and allows flexibility to pass through capillaries
Lack of nucleus and organelles
Maximizes space for hemoglobin but prevents self-repair
Membrane composition
Made of phospholipids, proteins and carbohydrate markers.
Cytoplasm
Primarily contains hemoglobin and enzymes for glycolysis