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Questions and Answers
What is the typical range of red blood cell (RBC) count in females, and what physiological factors affect this range?
What is the typical range of red blood cell (RBC) count in females, and what physiological factors affect this range?
What property of erythrocytes allows them to navigate through narrow blood vessels?
What property of erythrocytes allows them to navigate through narrow blood vessels?
At what point is the red blood cell (RBC) count generally at its highest?
At what point is the red blood cell (RBC) count generally at its highest?
Which adaptation of erythrocytes primarily contributes to their ability to pass through constricted areas in the circulatory system?
Which adaptation of erythrocytes primarily contributes to their ability to pass through constricted areas in the circulatory system?
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Which factor is least likely to contribute to variations in erythrocyte (RBC) counts?
Which factor is least likely to contribute to variations in erythrocyte (RBC) counts?
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What does the mode of adaptation 'plasticity' in erythrocytes imply in the context of their function?
What does the mode of adaptation 'plasticity' in erythrocytes imply in the context of their function?
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What can be inferred about erythrocyte abnormalities in relation to RBC count?
What can be inferred about erythrocyte abnormalities in relation to RBC count?
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Which of the following statements is accurate regarding red blood cell counts?
Which of the following statements is accurate regarding red blood cell counts?
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Why is plasticity a critical factor for erythrocytes in the circulatory system?
Why is plasticity a critical factor for erythrocytes in the circulatory system?
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How does the structural adaptation of erythrocytes affect their transport function?
How does the structural adaptation of erythrocytes affect their transport function?
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What characterizes the nucleus in the described cell type?
What characterizes the nucleus in the described cell type?
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Which statement best describes the composition of the cytoplasm in the cell?
Which statement best describes the composition of the cytoplasm in the cell?
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Which type of granule is characterized as smaller, numerous, and pale?
Which type of granule is characterized as smaller, numerous, and pale?
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What can be inferred about the Azurophilic granules in comparison to specific granules?
What can be inferred about the Azurophilic granules in comparison to specific granules?
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Which feature would you most likely not associate with this cell type?
Which feature would you most likely not associate with this cell type?
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Study Notes
Blood Composition
- Blood is a connective tissue, mesenchymal in origin.
- It's stained using a neutral stain like Leishman's stain (eosin + methylene blue dissolved in methyl alcohol).
- Blood cells comprise 45% of blood.
- Plasma makes up the remaining 55% of blood.
- The major component of plasma is water (90%).
Erythrocytes (Red Blood Cells)
- Originate in red bone marrow.
- Non-nucleated.
- Biconcave disc-shaped in side view; rounded in top view.
- Thickness: 2.2 µm at periphery, 0.8 µm at center.
- RBCs adhere to each other in slow circulation, forming stacks known as rouleaux. This is a temporary event.
- Surface tension causes these RBC stacks to sediment more easily, increasing Erythrocyte Sedimentation Rate (ESR).
- ESR increases with inflammation.
- Abnormal shapes include spherocytes (spherical), ovalocytes (oval), sickle cells (crescent-shaped), and poikilocytes (pear-shaped).
- These abnormal shapes are due to changes in the cell membrane or hemoglobin (Hb).
- Abnormal shapes are more fragile and prone to hemolysis, which leads to anemia.
Blood Cell Size and Color
- Normal RBC diameter: 6-9 µm, mean 7.5 µm.
- Abnormal sizes include microcytes (less than 6 µm) and macrocytes (more than 9 µm).
- Anisocytosis refers to different sizes of RBCs.
- RBCs appear colored due to hemoglobin (Hb).
- With Leishman's staining, RBCs appear acidophilic.
- Mature RBCs lack a nucleus and organelles.
Blood Cell Count
- Normal erythrocyte count in males: 5-5.5 million/mm³.
- Normal erythrocyte count in females: 4.5-5 million/mm³.
- Newborn babies have the highest RBC count, which then decreases over time.
- Anemia is characterized by a reduced number of RBCs below 4 million/mm³, or decreased hemoglobin concentration.
Polycythemia
- Increase in RBC count above 6 million/mm³ is called polycythemia.
- Polycythemia can be physiological (e.g., high altitudes, exercise, newborns) or pathological (e.g., chronic lung or heart diseases).
Erythrocyte Lifespan and Fate
- RBCs have a lifespan of about 120 days.
- Old RBCs are phagocytosed by macrophages in the liver, bone marrow, and spleen.
- Iron from broken-down RBCs is reused for new RBC production.
- Bile pigments are excreted as waste.
Erythrocyte Structure-Function Adaptations
- Plasticity (flexible shape) allows RBCs to squeeze through narrow vessels.
- Lipoproteins in RBC membranes are selective for gas exchange.
- Biconcave shape increases surface area for gas exchange.
- Rounded edges aid in easy flow through branched blood vessels (capillaries).
- Lack of nucleus/organelles frees up space for hemoglobin.
- Encased enzymes such as Hb reductase and carbonic anhydrase to bind/carry CO₂.
Leucocytes or White Blood Cells (WBCs)
- True cells having nuclei and organelles.
- Total WBC count: 4,000-11,000 cells/mm³.
- Differential count: percentage of each type of WBC.
- Abnormalities in total count include leukocytosis (> 11,000/mm³) due to physiological (pregnancy, exercise) or pathological (infection) reasons.
- Leukopenia (< 4,000/mm³) can occur due to x-rays, some antibiotics (chloramphenicol), and diseases like typhoid fever or influenza.
Granular Leucocytes
- Neutrophils (60-70%): Multilobed nucleus; numerous, fine, pale granules. First line of defense against bacteria via phagocytosis. Contain specific granules like phagocytin, lysozyme, and collagenase.
- Eosinophils (1-4%): Bilobed or horse-shoe-shaped nucleus; large, acidophilic granules. Related to parasitic infections and allergic reactions.
- Basophils (0-1%): Irregular/segmented nucleus; large basophilic granules; release histamine and heparin.
Non-Granular Leucocytes
- Lymphocytes (20-30%): Small to large; large nucleus with thin rim of cytoplasm. Important role in immunity. Three subtypes: cytotoxic (CD8), helper (CD4), regulatory/suppressor cells. Also includes NK cells.
- Monocytes (3-8%): Large, eccentric, kidney-shaped nucleus; pale basophilic cytoplasm with lysosomes. Differentiate into macrophages in tissues, involved in phagocytosis.
Comparison of Basophils and Mast Cells
- Basophils have a shorter lifespan and nucleus that are segmented or irregularly shaped.
- Mast cells have a longer lifespan, and a more rounder nucleus.
- Basophils granules are metachromatic.
- Mast cells stain with antibodies for relevant receptors.
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Description
This quiz covers the fundamentals of blood composition, focusing on the structure and function of erythrocytes (red blood cells). It examines aspects such as blood's connective tissue nature, plasma components, and the significance of erythrocyte morphology. Test your knowledge on these essential topics in human physiology.
