L32: Blood Cells

Question 1

Classification of blood cells

Answer 1

Multipotent haematopoietic stem cells

—> Myeloid stem cells

• Megakaryoblast —> platelets
• Proerythroblast —> reticulocyte —> RBC
• Myeloblast —> granuolcytes —> neutrophil, basophil, eosinophil
• Monoblast —> monocytes —> macrophage
• Mast cells
• Myeloid Dendritic cells

—> Lymphoid stem cells

• Lymphoblast —> NK cells, T lymphocyte, B lymphocyte —> plasma cells
• Lymphoid Dendritic cells

Leukocytes: neutrophil, basophil, eosinophil, monocyte, lymphocyte

Question 2

Site of haematopoiesis

Answer 2

1. Yolk sac / blastocystic cavity (3rd week during gastrulation)
2. Fetal liver
3. Red bone marrow
   - Red bone marrow —> yellow bone marrow (except rib, vertebrae, cranium etc.)
   - Yellow bone marrow (rich in adipose cells) retain haematopoietic potential

Question 3

Describe RBC

Answer 3

• no organelles (use anaerobic respiration to generate ATP)
• Haemoglobin give colour (heme: bind oxygen, globin: bind CO2)
• Glycoprotein/ glycolipid: blood group antigen
• 120 days cycle
• Spectrin and Actin for resilience and durability

Question 4

Describe erythropoiesis and destruction

Answer 4

Synthesis

• Erythropoietin from liver and kidney
• Erythropoiesis in Red bone marrow
• 3-5 days
• reduction in size, loss of nucleus and organelles, haemoglobin synthesis
• Iron, Vita B12 (cobalamin), B9 (folate)
• large amounts of reticulocyte —> indicate blood loss

Destruction

• 120 days cycle
• broken down in liver and spleen
• heme —> iron + bilirubin —> bile —> faeces
• globin —> free amino acids

Question 5

Blood types

Answer 5

A, B, AB, O

AB+: universal recipient
O-: universal donor

Question 6

Describe Neutrophils

Answer 6

• Most abundant leukocyte, also called PMN granulocyte
• Multi-lobed nucleus, condensed chromatin
• life span: 12-20 hours
• Acute inflammation
• Phagocytosis
• Primary / azurophilic granules: Myeloperoxidase
• Secondary / specific granules: Antibacterial protein (lysozyme)
• 14 microns (double size of RBC)

Question 7

Describe Eosinophils

Answer 7

Modulate:

• Allergy reaction by phagocytose Allergens, Ag-Ab complex
• Inflammatory reaction: Secrete enzymes in Parasitic infection
• Bi-lobed dumbbell shape
• Acidophilic, stain red

Question 8

Describe Basophils

Answer 8

• Rarest
• Allergic reaction similar to mast cells
• Secrete:
  1. Histamine
  2. Heparin
  3. Chemotactic signals
• Blueberry muffin: lots of blue granules, hidden bi-lobed nucleus

Question 9

Describe Monocytes

Answer 9

• Largest
• Horseshoe shaped nucleus
• Phagocytosis e.g. Kupffer cell (liver), Dust cell (lung), Microglia (CNS), Osteoclasts (bone)
• APC
• Mediator secretion
• Induction of general effects
• life span: months to years
• No granules

Question 10

Describe Platelets and thrombopoiesis

Answer 10

• Second most abundant
• 8-10 days cycle
• No nucleus
• secrete:
  1. Vasoconstrictor
  2. Temporary platelet plugs
  3. Clotting factors
  4. Chemotactic factors
  5. Growth factors
  6. Factor XII

Thrombopoiesis
Megakaryoblasts (25 micron, multiple nucleoli, basophilic)
—> Promegakaryoblast
—> Megakaryocyte (largest: 90 micron)
—> Platelet (3 micron)

Question 11

Describe Lymphocytes

Answer 11

• Smallest, second abundant (40%) after neutrophil
• Narrow rim of light blue cytoplasm

1. T lymphocyte (CD4, CD8, thymus dependent maturation, progeny from bone marrow)
2. B lymphocyte (memory B cell, plasma cell, produce antibodies, from bone marrow)
3. NK cells (Innate defence, non-MHC restricted cytotoxicity, from bone marrow)
4. Dendritic cells (APC)