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Questions and Answers
What is the primary function of mature erythrocytes?
What is the primary function of mature erythrocytes?
- To transport nutrients from the intestines to cells
- To deliver oxygen from the lungs to tissues and cells (correct)
- To produce hormones for metabolism
- To provide immunity against infections
What is a key morphological feature of mature erythrocytes?
What is a key morphological feature of mature erythrocytes?
- Presence of multiple nuclei
- Large size and round shape
- Biconcave shape with an anucleated structure (correct)
- High content of organelles
How long does it take for proerythroblasts to convert into mature erythrocytes?
How long does it take for proerythroblasts to convert into mature erythrocytes?
- 10 days
- 2 days
- 5 days
- 7 days (correct)
Which of the following factors is essential for erythropoiesis?
Which of the following factors is essential for erythropoiesis?
What happens to organelles during the maturation of erythrocytes?
What happens to organelles during the maturation of erythrocytes?
What is the main characteristic of the pronormoblast in terms of hemoglobin synthesis?
What is the main characteristic of the pronormoblast in terms of hemoglobin synthesis?
During which stage does hemoglobin synthesis begin?
During which stage does hemoglobin synthesis begin?
What is the typical N/C ratio of the polychromatic normoblast?
What is the typical N/C ratio of the polychromatic normoblast?
Which type of normoblast is characterized by having a small pyknotic nucleus and cannot synthesize DNA?
Which type of normoblast is characterized by having a small pyknotic nucleus and cannot synthesize DNA?
What does an increase in reticulocyte count indicate?
What does an increase in reticulocyte count indicate?
What morphological feature can be seen in reticulocytes?
What morphological feature can be seen in reticulocytes?
What is the primary function of erythrocytes?
What is the primary function of erythrocytes?
What is the significance of monitoring reticulocyte counts in newborns?
What is the significance of monitoring reticulocyte counts in newborns?
What is the primary function of erythropoietin in erythropoiesis?
What is the primary function of erythropoietin in erythropoiesis?
Which stage of erythropoiesis follows the basophilic normoblast?
Which stage of erythropoiesis follows the basophilic normoblast?
What significant change occurs to erythroid precursor cells during maturation?
What significant change occurs to erythroid precursor cells during maturation?
What is the WBC to RBC ratio mentioned in erythropoiesis?
What is the WBC to RBC ratio mentioned in erythropoiesis?
What type of cells are derived from pluripotential haematopoietic stem cells?
What type of cells are derived from pluripotential haematopoietic stem cells?
Which of the following is the committed stem cell for erythrocytes?
Which of the following is the committed stem cell for erythrocytes?
Why is the reticulocyte significant in the process of erythropoiesis?
Why is the reticulocyte significant in the process of erythropoiesis?
What change in the size of cells is observed from CFU-E to mature erythrocytes?
What change in the size of cells is observed from CFU-E to mature erythrocytes?
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Study Notes
Erythropoiesis
- Process of red blood cell development from early precursor cells to mature red blood cells.
- Erythropoietin is the primary regulator and stimulates red blood cell precursors to mature.
- Adult livers and spleens produce RBCs when bone marrow is damaged or fibrosed.
Bone Marrow
- Size equivalent to the liver in weight.
- Produces blood cells, including 75% leukocytes and 25% erythrocytes.
- The ratio of white blood cells to red blood cells is 1:500.
- Red blood cells have a shorter life span than white blood cells.
Process of Erythropoiesis
- Blood cells originate in the bone marrow from stem cells called pluripotential hematopoietic stem cells (PHSC).
- PHSCs are uncommitted and give rise to all blood cells.
- A small number of PHSCs remain undifferentiated to maintain the supply of stem cells.
- Committed PHSCs develop from uncommitted stem cells and differentiate into specific types of blood cells.
Colony Forming Units (CFU)
- CFU-E is a committed stem cell that forms erythrocytes.
- CFU-GM forms granulocytes and monocytes (neutrophils, eosinophils, basophils).
- CFU-M forms megakaryocytes which develop into platelets.
Changes During Erythropoiesis
- CFU-E mature through four stages.
- Cells decrease in size from 25 μm to 7.2 μm.
- The nucleus and nucleoli disappear.
- Hemoglobin production increases.
- Cytoplasm staining properties change.
Stages of Maturation
- Pronormoblast: The earliest and largest erythrocyte precursor cell with a large round nucleus and deeply blue-staining cytoplasm.
- Basophilic Normoblast: Characterized by the beginning of hemoglobin synthesis and a deeply basophilic cytoplasm.
- Polychromatic Normoblast: Shows an increased production of hemoglobin, resulting in a blue-gray to pink-gray cytoplasm.
- Orthochromatic Normoblast: The last nucleated stage, with a small, dense nucleus and abundant red-orange cytoplasm.
- Reticulocyte: An immature red blood cell with residual RNA.
- Mature Erythrocyte: A biconcave 6-8 μm disc with a 120-day lifespan. It contains 90% hemoglobin and 10% water.
Mature Erythrocytes
- Biconcave shape with a diameter of 7-8 μm.
- Anucleated (lacks a nucleus).
- Cytoplasm stains pink in color.
- Reticular network disappears as the cell matures.
- 7 days for proerythroblasts to become mature erythrocytes.
- 5 days for proerythroblasts to become reticulocytes.
- 2 days for reticulocytes to become mature erythrocytes.
Erythropoiesis Summary
- Cell size, nucleus size, and basophilia decrease during maturation.
- Organelles disappear, and the nucleus is extruded.
- Ribosomes disappear in the transition from reticulocytes to erythrocytes.
Factors Necessary for Erythropoiesis
- Classified into three categories:
- General Factors: Erythropoietin, thyroxine, hemopoietic growth factors, and vitamins.
- Maturation Factors: Vitamin B12, intrinsic factor, and folic acid.
- Factors Necessary for Hemoglobin Formation: Iron.
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