Blood Cell Development Quiz

Blood Cell Development

• Blood consists of whole blood, plasma, and formed elements like erythrocytes, leukocytes, and platelets.
• Whole blood composition includes water (92%), proteins, electrolytes, nutrients, respiratory gases, and waste products. Erythrocytes make up 4.2-6.2 million per cubic mm.
• Leukocytes (white blood cells) are 5-10 thousand per cubic mm, categorized as granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (monocytes, lymphocytes).
• Platelets (thrombocytes) range from 150,000 to 400,000 per microliter of blood.

Erythrocytes (Red Blood Cells)

• Most abundant blood cells, flexible biconcave discs.
• 6-9 µm average diameter, 2.5 µm rim thickness, and 0.75 µm center thickness.
• Non-nucleated with a pale center.
• Life span of 120 days; engulfed by macrophages.
• Abnormal shapes include sickle shape and spherocytosis.
• Abnormal sizes include microcytic (diameter <6 µm) and macrocytic (diameter >9 µm).

Leukocytes (White Blood Cells)

• There are different types of leukocytes or white blood cells. Different types of leukocytes are divided into granulocytes and agranulocytes
• Granulocytes:
  • Neutrophils (60-70% of circulating leukocytes), size 12-15 µm, segmented nucleus (2–5 lobes), cytoplasm with granules. Life span of 1-4 days.
  • Eosinophils (2-4% of circulating leukocytes), size 12-15 µm, bilobed nucleus, cytoplasmic granules, acidophilic. Life span of 8-12 days.
  • Basophils (less than 1% of circulating leukocytes), size 12-15 µm, 2 irregular lobes, cytoplasm with granules which stain purple, obscure the shape, contain histamine and heparin. Life span of 10-15 days.
• Agranulocytes:
  • Monocytes (3-8% of circulating leukocytes), size 15-20 µm (largest in blood smear), Indented nucleus (C, kidney-shaped), basophilic cytoplasm with azurophilic granules. Life span of 3 days, precursor of macrophages.
  • Lymphocytes (20-25% of circulating leukocytes):
    • Small lymphocytes (10-12 µm) with a spherical, highly condensed nucleus, thin rim of cytoplasm.
    • Medium and Large lymphocytes (7-15 µm diameter) with a more extensive cytoplasm containing few azurophilic granules, slightly indented nucleus.
    • Responsible for both antibody-mediated immunity (B lymphocytes) and cell-mediated immunity (T lymphocytes).

Platelets (Thrombocytes)

• Small, non-nucleated cell fragments.
• Diameter: 2-4 µm
• Normal count: 150,000–400,000/µL blood
• Life span: about 10 days
• Stained smears show platelets in clumps, with a light peripheral zone (hyalomere) and a darker central zone (granulomere).

Hemopoiesis (Blood Cell Formation)

• Formation of blood cells from hematopoietic stem cells in bone marrow.
• Myeloid stem cells differentiate into erythrocytes, platelets, granulocytes, and monocytes.
• Lymphoid stem cells form lymphocytes (B cells, T cells, and natural killer cells).
• Various growth factors (e.g., erythropoietin, thrombopoietin, colony-stimulating factors) regulate hemopoiesis. 

Blood Smear Preparation

• Blood sample collection involves pricking the finger.
• A drop of blood is placed on a slide and spread across with a second slide, leaving a thin layer, for contrast a stain is used.
• A coverslip is placed on top.

Test your knowledge on blood cell types and their characteristics. This quiz covers erythrocytes, leukocytes, and platelets, along with their composition and functions in the human body. Perfect for students studying biology or health sciences.