Red Blood Cell

**Red Blood Cells **

Q1: What is the normal structure of RBC with its morphology?

The normal structure of RBC consists of a biconcave disk-shaped cytoplasm surrounded by a thin, flexible membrane. The cytoplasm contains a network of thin, branching tubules called the reticular network, which gives the RBC its characteristic biconcave shape. The RBC also contains the following components:

• Hemoglobin: a protein that carries oxygen from the lungs to the tissues
• Cytosol: the fluid portion of the cytoplasm
• Nucleus: absent in adults, but present in developing RBCs
• Mitochondria: absent in RBCs
• Ribosomes: absent in RBCs

The morphology of RBCs can be abnormal in certain conditions, such as anemia, where the RBCs may be smaller, larger, or irregularly shaped.

Q2: Discuss the stages and regulation of erythropoiesis.

Erythropoiesis is the process by which RBCs are produced in the bone marrow. The stages of erythropoiesis are as follows:

1. Proerythroblast: the first stage of erythropoiesis, characterized by a large, round cell with a large nucleus
2. Basophilic erythroblast: the second stage, characterized by a smaller nucleus and a larger cytoplasm
3. Polychromatic erythroblast: the third stage, characterized by a further reduction in nucleus size and an increase in cytoplasm
4. Orthochromatic erythroblast: the fourth stage, characterized by a small nucleus and a large, deeply staining cytoplasm
5. Reticulocyte: the final stage, characterized by a small nucleus and a large, pale cytoplasm
6. RBC: the mature cell, characterized by the absence of a nucleus and a large, biconcave disk-shaped cytoplasm

The regulation of erythropoiesis is controlled by the following factors:

• Hormones: erythropoietin (EPO) and thyroid hormone
• Growth factors: interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF)
• Nutrients: iron and vitamins

Q3: What is the fate of RBC?

The fate of RBCs is as follows:

• Circulation: RBCs circulate in the blood for approximately 120 days
• Senescence: RBCs eventually become old and are removed from the circulation
• Phagocytosis: RBCs are phagocytosed by macrophages in the spleen and liver
• Hemoglobin degradation: the hemoglobin is broken down into bilirubin, which is then excreted in the bile

Q4: Discuss hemolysis.

Hemolysis is the breakdown of RBCs, leading to the release of hemoglobin into the blood. The causes of hemolysis include:

• Inherited disorders: such as sickle cell anemia
• Acquired disorders: such as autoimmune hemolytic anemia
• Toxins: such as snake venom
• Infections: such as malaria

The consequences of hemolysis include:

• Anemia: a decrease in the number of RBCs
• Jaundice: a yellowing of the skin and eyes due to the buildup of bilirubin
• Hemoglobinuria: the presence of hemoglobin in the urine