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Questions and Answers
What percentage of the RBC cell membrane is composed of proteins?
What percentage of the RBC cell membrane is composed of proteins?
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Which protein network provides structural support and flexibility to the RBC membrane?
Which protein network provides structural support and flexibility to the RBC membrane?
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What is the primary source of energy for RBCs?
What is the primary source of energy for RBCs?
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Which type of progenitor cell gives rise to lymphocytes?
Which type of progenitor cell gives rise to lymphocytes?
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Reticulocytes make up approximately what percentage of total RBCs in peripheral blood?
Reticulocytes make up approximately what percentage of total RBCs in peripheral blood?
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Which of the following statements about the structure of RBCs is FALSE?
Which of the following statements about the structure of RBCs is FALSE?
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Which of the following is a characteristic of a proerythroblast?
Which of the following is a characteristic of a proerythroblast?
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Which stage of erythropoiesis is characterized by the extrusion of the nucleus?
Which stage of erythropoiesis is characterized by the extrusion of the nucleus?
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Which of the following conditions is associated with RBCs larger than 9 μm in diameter?
Which of the following conditions is associated with RBCs larger than 9 μm in diameter?
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Which of the following is NOT a stage in the differentiation of a pluripotential hemopoietic stem cell into a mature erythrocyte?
Which of the following is NOT a stage in the differentiation of a pluripotential hemopoietic stem cell into a mature erythrocyte?
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Which of the following cells gives rise to platelets?
Which of the following cells gives rise to platelets?
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What is the normal shape of red blood cells (RBCs) as seen in a stained blood smear?
What is the normal shape of red blood cells (RBCs) as seen in a stained blood smear?
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What is the average diameter of a normal RBC?
What is the average diameter of a normal RBC?
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Which of the following conditions is associated with RBCs larger than 9 μm in diameter?
Which of the following conditions is associated with RBCs larger than 9 μm in diameter?
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What is the function of the network of proteins (spectrin, ankyrin, and actin) in the RBC membrane?
What is the function of the network of proteins (spectrin, ankyrin, and actin) in the RBC membrane?
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What is the main component of the RBC cytoplasm?
What is the main component of the RBC cytoplasm?
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How long is the average lifespan of an RBC?
How long is the average lifespan of an RBC?
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Which cells are responsible for removing dead or worn-out RBCs from circulation?
Which cells are responsible for removing dead or worn-out RBCs from circulation?
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What is the term for the process of blood cell formation?
What is the term for the process of blood cell formation?
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All blood cells are derived from which type of cell?
All blood cells are derived from which type of cell?
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What is the first precursor (blast cell) of RBCs?
What is the first precursor (blast cell) of RBCs?
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How does the biconcave shape of RBCs facilitate gas exchange?
How does the biconcave shape of RBCs facilitate gas exchange?
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What is the significance of RBCs lacking a nucleus and cell organelles?
What is the significance of RBCs lacking a nucleus and cell organelles?
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In sickle cell disease, what is the consequence of the abnormal shape of RBCs?
In sickle cell disease, what is the consequence of the abnormal shape of RBCs?
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What is the clinical significance of reticulocytosis (increased reticulocytes in blood)?
What is the clinical significance of reticulocytosis (increased reticulocytes in blood)?
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What are Romanowsky stains used for in histology?
What are Romanowsky stains used for in histology?
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What is the difference between a myeloid stem cell and a lymphoid stem cell?
What is the difference between a myeloid stem cell and a lymphoid stem cell?
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Describe the changes in the nucleus and cytoplasm during erythropoiesis.
Describe the changes in the nucleus and cytoplasm during erythropoiesis.
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What is the function of antigens on the RBC membrane?
What is the function of antigens on the RBC membrane?
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Why is the flexibility of the RBC membrane important?
Why is the flexibility of the RBC membrane important?
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What happens to the hemoglobin released from ruptured RBCs?
What happens to the hemoglobin released from ruptured RBCs?
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Which stain is a mixture of acidic and basic dyes?
Which stain is a mixture of acidic and basic dyes?
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What are the two types of progenitor cells derived from the pluripotential hemopoietic stem cell?
What are the two types of progenitor cells derived from the pluripotential hemopoietic stem cell?
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In which stage of erythropoiesis does hemoglobin synthesis begin?
In which stage of erythropoiesis does hemoglobin synthesis begin?
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What is the characteristic feature of a reticulocyte?
What is the characteristic feature of a reticulocyte?
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What is the normal concentration of RBCs in blood for females?
What is the normal concentration of RBCs in blood for females?
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Study Notes
Structure and Shape of RBCs
- Normal shape of RBCs is a biconcave disc, enhancing surface area for gas exchange.
- Biconcave shape improves flexibility and facilitates efficient movement through blood vessels.
- Abnormal shapes, such as sickle-shaped RBCs, are associated with conditions like sickle cell anemia.
- Average diameter of RBCs ranges from 6-9 μm.
Concentration and Composition
- Normal RBC concentration in males is between 4.1-6.0 million/μL.
- The RBC membrane contains approximately 50% proteins, contributing to its structure and function.
Membrane and Energy
- The RBC membrane's structural support comes from a protein network of spectrin, ankyrin, and actin.
- RBCs primarily produce energy through anaerobic glycolysis, as they lack mitochondria.
Lifespan and Removal
- The average lifespan of an RBC is about 120 days before being removed by macrophages in the spleen and liver.
Hemopoiesis
- Hemopoiesis refers to the process of blood cell formation, primarily occurring in the bone marrow of adults.
- All blood cells originate from pluripotential hemopoietic stem cells.
- Lymphocytes arise from lymphoid stem cells, while erythropoiesis begins with proerythroblasts.
Erythropoiesis Process
- The first precursor in the erythropoiesis lineage is the proerythroblast, followed by stages like basophilic and orthochromatophilic erythroblasts.
- The nucleus is extruded during the orthchromatophilic erythroblast stage, producing reticulocytes that lack a nucleus.
- Reticulocytes normally make up about 1% of total RBCs in peripheral blood.
Disorders and Characteristics
- Reticulocytosis indicates an increased percentage of reticulocytes in the bloodstream.
- Sickle-shaped RBCs are less flexible, more fragile, and have a shorter lifespan compared to normal RBCs.
- Conditions such as macrocytic anemia involve RBCs larger than 9 μm in diameter.
Stains and Techniques
- Romanowsky stains, including Leishman's stain, Giemsa stain, and Wright stain, are used for blood smear examination.
- Stacks of RBCs adhering together are termed rouleaux, often visible under certain conditions.
Other Key Facts
- Antigens on RBC surfaces are crucial for blood group determination.
- Hemopoiesis sites in adults include the vertebrae, ribs, and sternum, but not the liver, which is a fetal site.
- CFU-Meg cells are responsible for platelet production, while pluripotential hematopoietic stem cells maintain their own population.
Red Blood Cells (RBCs) Overview
- RBCs are normally shaped as biconcave discs, which enhance their flexibility and surface area for gas exchange.
- Average diameter of an RBC is approximately 6-9 μm.
- Macrocytic anemia is characterized by RBCs larger than 9 μm in diameter.
RBC Structure and Function
- The network of proteins, including spectrin, ankyrin, and actin, provides support and flexibility to the RBC membrane.
- Hemoglobin is the main component of RBC cytoplasm, crucial for oxygen transport.
- Average lifespan of an RBC is approximately 120 days.
RBC Maintenance and Production
- Macrophages are responsible for removing dead or worn-out RBCs from circulation.
- Erythropoiesis refers to the process of blood cell formation, originating from pluripotential hemopoietic stem cells.
- The first precursor of RBCs is the proerythroblast.
Complex RBC Features
- The biconcave shape of RBCs increases surface area, facilitating more efficient gas exchange.
- Lack of a nucleus and organelles in RBCs allows for greater hemoglobin capacity and enhances their oxygen transport.
- Sickle cell disease leads to decreased flexibility, fragility, and a shortened lifespan of RBCs.
Clinical Aspects
- Reticulocytosis indicates increased production of RBCs, often in response to blood loss or hemolysis.
- Romanowsky stains are commonly used in histology to stain blood cells, providing contrast for better visualization.
Stem Cells and Erythropoiesis
- Myeloid stem cells give rise to RBCs, WBCs, and platelets, while lymphoid stem cells specifically produce lymphocytes.
- During erythropoiesis, the nucleus shrinks and is eventually extruded, with cytoplasm changing from basophilic to acidophilic as hemoglobin synthesis begins in the basophilic erythroblast stage.
Antigens and RBC Membrane Flexibility
- Antigens on RBC membranes play a crucial role in determining blood type.
- Flexibility of the RBC membrane is crucial for navigating through small capillaries without rupturing.
Hemoglobin Management
- When RBCs rupture, hemoglobin is phagocytosed by macrophages.
- Stains such as Leishman's, Giemsa, Wright, and Romanowsky stains utilize mixtures of acidic and basic dyes for effective visualization of blood cells.
RBC Concentration
- Normal RBC concentration in females ranges from 3.9 to 5.5 million per μL of blood.
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