Questions and Answers
Which of the following are types of formed elements?
What is the main function of erythrocytes?
To carry oxygen
What is hemoglobin?
What does anemia indicate?
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What leads to sickle-cell anemia?
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What is polycythemia?
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What is leukocytosis?
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What is leukopenia?
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What happens in leukemia?
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Which is not a type of leukocyte?
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Match the following types of leukocytes with their characteristics:
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What is the normal platelet count per cubic millimeter of blood?
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Study Notes
Types of Formed Elements
- Erythrocytes are red blood cells (RBCs) that primarily carry oxygen.
- Leukocytes are white blood cells (WBCs) crucial for immune defense.
- Platelets are cell fragments essential for blood clotting.
Erythrocytes Overview
- Function: Oxygen transport.
- Structure: Biconcave disks, essentially bags of hemoglobin, anucleate, with few organelles.
- Normal count: Approximately 5 million RBCs per cubic millimeter of blood.
Hemoglobin
- Composition: Iron-containing protein that binds oxygen.
- Structure: Each molecule has four oxygen-binding sites; each erythrocyte contains about 250 million hemoglobin molecules.
- Normal concentration: 12-18 g of hemoglobin per 100 mL of blood.
Anemia
- Definition: Decrease in the blood's oxygen-carrying capacity.
Sickle-cell Anemia (SCA)
- Cause: Abnormally shaped hemoglobin leads to distorted RBC shape.
Polycythemia
- Definition: Excessive increase in RBC count.
- Causes: Can result from bone marrow cancer (polycythemia vera) or adaptation to high altitudes (secondary polycythemia).
- Effect: Increased RBCs result in slower blood flow and higher viscosity, impairing circulation.
Leukocytes Overview
- Function: Defense against disease; complete cells with nuclei and organelles.
- Movement: Capable of diapedesis (moving out of blood vessels) and amoeboid motion.
- Response: Move toward damaged tissues through positive chemotaxis.
- Normal count: Ranges from 4,800 to 10,800 WBCs per cubic millimeter of blood.
Leukocytosis
- Definition: Elevated WBC count (above 11,000 cells/mm³), typically indicating infection.
Leukopenia
- Definition: Low WBC count, often due to drugs like corticosteroids and anticancer agents.
Leukemia
- Definition: Cancer of the bone marrow, producing excess WBCs.
Granulocytes
- Characteristic: Cytoplasmic granules can be stained; contain lobed nuclei.
- Types: Neutrophils, eosinophils, and basophils.
Agranulocytes
- Characteristic: Lack visible granules; nuclei are spherical, oval, or kidney-shaped.
- Types: Lymphocytes and monocytes.
Abundance of WBCs
- Order from most to least abundant:
- Neutrophils → Lymphocytes → Monocytes → Eosinophils → Basophils.
Neutrophils
- Appearance: Pale pink cytoplasm, fine granules, deep purple lobed nucleus.
- Role: Act as phagocytes during infections.
- Normal count: 3,000-7,000 cells/mm³ (40-70% of WBCs).
Eosinophils
- Appearance: Red granules, bilobed nucleus.
- Role: Combat parasitic infections and mediate allergy responses.
- Normal count: 100-400 cells/mm³ (1-4% of WBCs).
Basophils
- Appearance: Sparse large blue-purple granules, U- or S-shaped nucleus.
- Function: Release histamine (a vasodilator) and contain heparin (an anticoagulant).
- Normal count: 20-50 cells/mm³ (0-1% of WBCs).
Lymphocytes
- Appearance: Pale blue cytoplasm and dark purple nucleus.
- Role: Integral to the immune system; B lymphocytes produce antibodies, T lymphocytes target tumors and viruses.
- Normal count: 1,500-3,000 cells/mm³ (20-45% of WBCs).
Monocytes
- Appearance: Largest WBCs with gray-blue cytoplasm, kidney-shaped nucleus.
- Role: Function as macrophages; important in chronic infection response.
- Normal count: 100-700 cells/mm³ (4-8% of WBCs).
Platelets
- Origin: Derived from ruptured megakaryocytes.
- Function: Essential for blood clotting processes.
- Normal count: 150,000 to 400,000 platelets/mm³, with 300,000 considered average.
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Description
This quiz covers the key types of formed elements in blood, including erythrocytes, leukocytes, and platelets. You'll learn about their structures, functions, and conditions like anemia and sickle-cell anemia. Test your knowledge of blood components and their importance in the body.
