WEEK 9 Flashcards
(12 cards)
What are the components of blood
- plasma
- white blood cells (leucocytes)
- platelets
- red blood cells (erythrocytes)
Process of Haematopoiesis
- Haematopoietic stem cell becomes a multi potent stem cell
- Multi potent stem cell becomes a) lymphoid progenitor cell or b) myeloid progenitor cell
- Lymphoid progenitor cell becomes either; T lymphocyte, natural killer, B lymphocyte
- Myeloid progenitor cell becomes either; neutrophil, basophil, monocyte/ macrophage, platelets, granulocytes, easinophil
What are the functions of platelets?
- prevent blood loss by forming a thrombus (clot)
- adhere to damaged blood vessel walls
- aggregate together to form a platelet plug
- aid coagulation enzymes in forming insoluble strands of fibrin that holds platelet plug & trapped RBCs to form “blood clot”
What are the white blood cells’ functions?
• Neutrophils:
- Anti-bacterial cells - eat bacteria (phagocytosis)
- Rapid to infection site (minutes), form ‘pus’.
• Eosinophils:
- Destroy parasites extracellularly (release enzymes, oxidants)
- Also weakly phagocytic (of allergens)
• Basophils:
- Activate other WBCs during inflammation & allergic reactions (release histamine)
• Monocytes:
- become macrophages (powerful phagocytes)
Lymphocytes: respond to foreign substances/cells
B lymphocytes (PRODUCE ANTIBODIES):
- ~20% of circulating lymphocytes
- Proliferate and become plasma cells that produce antibodies (humoral immunity)
T lymphocytes ( DOESN’T MAKE ANTIBODIES)
- ~80% of circulating lymphocytes
- Proliferate & become activated T-cells (cell-mediated immunity) that kill foreign invading cells or altered
cells
Structure of Red blood cells
• Biconcave disc
- 7 — 8 pm diameter
- 2 pm high
• Consists of membrane enclosing
- Water
- electrolytes
- haemoglobin
- metabolic enzymes
• No nucleus or organelles
Functions of the Red blood cells
• Oxygen transport:
- 02 binds reversibly to haemoglobin (Hb) in RBC
- lg Hb can bind 1.39 mL 02
• Carbon dioxide transport:
- Carbonic anhydrase in RBC catalyses the reaction
C02 + H20 ⇔ H2CO3 ⇔ HCO3- + H+
- Hb in RBC (and proteins in plasma) bind C02
Function of Haemoglobin
O2 binds loosely &reversely to Fe2+ of Hb (i.e. carries oxygen)
Red blood cell Destruction
• No nucleus = can’t repair — won’t last long!
• Life span ~120 days
• Old cells removed by SPLEEN, liver & bone marrow
• Removed due to
- reduced flexibility
- Rupture
• Phagocytosed by macrophages
- Fe recycled
- Rest of Hb disposed of (bilirubin)
Process of Erythropoiesis
- Stem cell: Hemocytoblast
- Committed cell: Proerythrocyteblast
- Developmental Pathway:
- Phase 1: ribosome synthesis (early erythroblast)
- Phase 2: Haemoglobin accumulation (late erythoblast to normoblast)
- Phase 3: Ejection of nucleus through exocytosis (reticulocyte to erythrocyte)
Red Blood cell count (RBC) in both male and female
Male: 5.0 x 10^12 cells/L
Female: 4.8 x 10^12 cells/L
Concentration of Haemoglobin ([Hb]) in both male and female
Male: 150 g/L
Female: 135 g/L
Haematocrit (PVC) in both male and female
Male: 0.45
Female: 0.42
